Cylinder Volume Calculator – Volume, Surface Area and Missing Dimensions
A cylinder is just a circle with depth — so its volume is the base circle’s area piled up to the full height: V = πr²h. Type in a radius (or a diameter) and a height and this calculator works out the volume, the total, lateral and end-cap surface areas, and how many litres the cylinder holds. Working backwards instead? Switch modes and it finds the height or the radius a target volume needs — then rebuilds the volume from its own answer to prove it.
Your cylinder
What do you want to find?
Enter the size as
Unit for every length
You are entering the diameter — the radius used in the maths is half of it, and the answer is identical.
The cylinder loaded is a can with radius 5 cm and height 10 cm — small enough that every answer below can be checked against 250π by hand. Pick a unit first, then type: the numbers you enter are read in the unit you picked.
🔒 Everything is calculated in your browser — your numbers never leave your device.
Advanced options — hollow wall, tank fill, weight and cost, and more units
These extras are readouts only: they never change the main answers above. Leave wall thickness at 0 for a solid cylinder and fill at 100 for a full one. Weight uses the wall material when a wall thickness is set, otherwise the full cylinder volume.
The answer
The full picture
The working, step by step
Every answer on this page is one short chain of arithmetic. Here it is with your numbers in it — change any input and the working rewrites itself.
Base area = π × r² = π × 5² = π × 25 = 78.54 cm²
Volume = base area × height = 78.54 × 10 = 785.398 cm³
Lateral (side) area = 2πrh = 2π × 5 × 10 = 314.159 cm² — the wall you would paint or wrap
Total surface area = side + two caps = 314.159 + 157.08 = 471.239 cm², which is also 2πr(r + h) = 2π × 5 × (5 + 10)
With d = 10, π × (d ÷ 2)² × h = π × 5² × 10 = 785.398 cm³ — identical, as it must be.
Key takeaways
- Volume is the base circle stacked through the height: V = πr²h. Doubling the radius quadruples the volume, while doubling the height only doubles it.
- A hollow cylinder uses the annulus π(R² − r²), and fill percent means the same percent of height and volume in an upright tank — but a horizontal tank needs the circular-segment formula.
- Convert before comparing: 1 m³ = 1,000 litres = 264.172 US gallons, and weight is volume × density, so the same cylinder weighs nearly eight times as much in steel as in water.
Contents
- See it: your cylinder, drawn to its own proportions
- Keep going with shapes and measures
- How it works, in 3 steps
- How each answer is worked out
- Deep dives
- Hollow cylinders and pipes: the annulus, done properly
- Tank fill levels: percent full, filled height and remaining capacity
- Volume in litres, gallons and cubic feet: the conversion table
- Weight and cost from volume: density does the work
- Volume and surface area at a glance: a reference table
- Frequently asked questions
See it: your cylinder, drawn to its own proportions
The drawing below is not decoration — it stretches and squashes with your numbers. A wide, flat cylinder and a tall, thin one with the same volume look completely different, and the proportions are usually where a wrong answer first shows itself.
Keep going with shapes and measures
How it works, in 3 steps
Measure one circle
Everything starts with the base: its area is πr², and if you were given the diameter instead, halving it gives the radius. Get this one circle right and the rest of the page is arithmetic.
Stack it through the height
Volume is the base area multiplied by the height — the circle swept upwards. The side wall is just as simple: unrolled, it is a rectangle whose width is the circumference 2πr and whose height is h.
Or run it backwards
Divide a target volume by the base area to get the height it needs; divide by πh and take the square root to get the radius. Either way, the volume is then rebuilt from the answer as a standing check.
How each answer is worked out
Worked example — the can loaded above. Radius 5 cm, height 10 cm. The base is π × 5² = 78.54 cm², so the volume is 78.54 × 10 = 785.398 cm³ — exactly 250π. The side wall is 2π × 5 × 10 = 314.159 cm², the two caps add 2 × π × 5² = 157.08 cm², and the total surface is 471.239 cm². In litres, the can holds 0.785 L.
Worked example — a water tank. Radius 2 m, height 3 m. Volume = π × 2² × 3 = 12π ≈ 37.699 m³, which is 37,699 litres. Total surface area = 2π × 2 × (2 + 3) = 62.832 m² — the number that matters if the tank is being lined or painted inside and out.
Worked example — backwards, both ways. A tin must hold exactly 1 litre (1,000 cm³) with a radius of 5 cm: h = 1,000 ÷ (π × 25) = 12.732 cm. Turn it around — the same litre at a fixed height of 10 cm needs r = √(1,000 ÷ (π × 10)) = √31.831 = 5.642 cm. Two different questions, one formula read in two directions.
Worked example — you only have the diameter. A soup can measures 7.5 cm across and 11 cm tall. Halve the diameter: r = 3.75 cm. Volume = π × 3.75² × 11 = π × 154.6875 ≈ 485.96 cm³, about 0.486 litres — which is why the label on such a can says roughly 485 ml.
Deep dives
The r² in πr² is doing heavy lifting. Double the radius of a cylinder and its base does not double — it quadruples, because the circle grows in two directions at once. At the same height the volume quadruples too: a tank twice as wide holds four times as much, while a tank twice as tall holds only twice as much. Width is always the more powerful dimension.
That same square is behind the most common cylinder mistake in the world: typing the diameter where the radius belongs. Because the value gets squared, the answer does not come out doubled — it comes out four times too big, and an oversized tank or a quadruple batch of concrete gets ordered. It is exactly why this page takes the diameter directly, halves it for you, and runs a standing check that both measurements produce the same volume.
The calculator treats the numbers you type as the cylinder’s inside dimensions and its shape as perfect. Real containers are less tidy. A tank measured from the outside loses capacity to its wall thickness on every side — a few millimetres of steel on a small tank can cost several percent of the volume — and curved or dished ends are not true cylinders at all.
Then there is the fill line: almost nothing is filled to the brim. Fuel and water expand, fermenters need headspace, and a “500 litre” tank is usually 500 litres to its safe working level, not to its lip. Use this page’s figure as the geometric truth, then subtract your own allowance for walls and headspace — the maths is exact, and the allowance is yours to judge.
Hollow cylinders and pipes: the annulus, done properly
A pipe is a cylinder with a cylinder missing from the middle. The material of the wall is the ring between the outer circle and the inner circle, and that ring has a name: the annulus. If the outer radius is R and the wall thickness is t, the inner radius is r = R − t, the annulus area is π × (R² − r²), the wall material volume is the annulus area × length, and the usable bore volume is π × r² × length. Nothing else changes: the bore is an ordinary cylinder, and the wall is an ordinary cylinder minus that bore.
Take the pipe the Advanced options default to when you set a wall. Outer radius 5 cm, wall 0.5 cm, so the inner radius is 4.5 cm. The annulus area is π × (25 − 20.25) = π × 4.75 = 14.923 cm². Over one metre of pipe the wall material is 14.923 × 100 = 1,492.257 cm³, while the bore holds π × 4.5² × 100 = 6,361.725 cm³, or 6.362 litres. The solid cylinder of the same outside size would be π × 25 × 100 = 7,853.982 cm³ per metre, and the two parts add back to it exactly: 1,492.257 + 6,361.725 = 7,853.982. That add-back is the quickest check that a pipe calculation is right.
A smaller pipe shows the same arithmetic at a different scale. Outer diameter 6 cm means outer radius 3 cm; with a 0.4 cm wall the inner radius is 2.6 cm, the annulus area is π × (9 − 6.76) = π × 2.24 = 7.037 cm², the wall material is 703.717 cm³ per metre, and the bore holds π × 2.6² × 100 = 2,123.717 cm³, or 2.124 litres, per metre. A larger pipe, outer diameter 20 cm with a 1 cm wall, has inner radius 9 cm, annulus area π × (100 − 81) = 59.690 cm², wall material 5,969.026 cm³ per metre, and a bore of π × 81 × 100 = 25,446.901 cm³, or 25.447 litres, per metre. In every case the wall thickness comes off the radius twice over in the diameter: a 0.5 cm wall makes the bore diameter a full 1 cm smaller than the outside diameter, which is the slip that catches people who measure the outside and forget the wall.
| Pipe (outside diameter, wall) | Inner diameter | Annulus area | Wall material per metre | Bore capacity per metre |
|---|---|---|---|---|
| 10 cm, 0.5 cm wall | 9 cm | 14.923 cm² | 1,492.257 cm³ | 6.362 litres |
| 6 cm, 0.4 cm wall | 5.2 cm | 7.037 cm² | 703.717 cm³ | 2.124 litres |
| 20 cm, 1 cm wall | 18 cm | 59.690 cm² | 5,969.026 cm³ | 25.447 litres |
Two measuring notes matter more than the formula. First, pipes are usually sold by outside diameter, so halve that figure for R before subtracting the wall; starting from the bore diameter instead gives the inner volume directly but tells you nothing about the wall. Second, the wall thickness must be smaller than the outer radius, or there is no bore left at all — a wall as thick as the radius is a solid rod, not a pipe. The Advanced options on this page enforce that limit: set a wall thickness there and it reports the inner radius, the material volume and the usable volume for your own cylinder, in whatever unit you are working in. For an open-topped container the same idea applies in a simpler form: the volume is unchanged, only one end cap drops out of the surface area, as the last of the original questions below explains.
Tank fill levels: percent full, filled height and remaining capacity
For a tank standing upright, fill percentage is beautifully simple, because every horizontal slice of the tank has the same area. Fill the tank to half its height and it holds half its volume; fill it to three quarters of its height and it holds three quarters of its volume. In symbols, filled height = percentage × total height, filled volume = percentage × total volume, and remaining volume = total volume − filled volume. There is no curve to correct for and no table to look up, which is why upright tanks are the easy case and the one the Advanced fill control on this page answers.
The tank used as an example throughout this page makes the point concretely. Radius 2 m, height 3 m, full volume π × 4 × 3 = 37.699 m³, or 37,699 litres. At 25% it holds 9,425 litres at a depth of 0.75 m; at 50% it holds 18,850 litres at 1.5 m; at 75% it holds 28,274 litres at 2.25 m; at 90% it holds 33,929 litres at 2.7 m, leaving 3,770 litres of headspace. Read a dipstick or a sight gauge in an upright tank and the depth reading converts straight to a percentage: depth ÷ total height × 100. If the gauge reads 2.25 m in this 3 m tank, the tank is 75% full, and the remaining capacity is the other 25%, 9,425 litres.
| Fill level | Filled height (3 m tank) | Filled volume | Remaining volume |
|---|---|---|---|
| 25% | 0.75 m | 9,425 litres | 28,274 litres |
| 50% | 1.5 m | 18,850 litres | 18,850 litres |
| 75% | 2.25 m | 28,274 litres | 9,425 litres |
| 90% | 2.7 m | 33,929 litres | 3,770 litres |
A tank lying on its side breaks that simplicity, and it is worth knowing why rather than guessing. In a horizontal cylinder the liquid surface gets wider as the level rises towards the middle and narrower again towards the top, so equal steps of depth hold unequal volumes: the percentage rises slowly near the bottom, fastest at the middle, and slowly again near the top. The filled cross-section is a circular segment, with area A = r² × cos⁻¹((r − h) ÷ r) − (r − h) × √(2rh − h²), where h is the liquid depth and r is the tank radius; multiply by the tank length for the volume. Half full is still exactly 50%, because the segment at depth equal to the radius is a perfect semicircle. But a depth of 0.5 m in a horizontal tank of radius 1 m and length 3 m gives a segment area of 0.614 m² and a volume of 1.843 m³, or 1,843 litres — only 19.6% of the full 9.425 m³, not the 25% a straight proportion would suggest. Treat any horizontal-tank percentage that was worked out by proportion alone as wrong, and use the segment formula or a strapping table for the tank in question. The Advanced fill control on this page is labelled for upright tanks only, for exactly this reason.
Volume in litres, gallons and cubic feet: the conversion table
Cylinder volumes arrive in cubic units and get used in litres, gallons and cubic feet, so the conversions are part of the calculation, not an afterthought. The exact anchors are few: one litre is exactly 1,000 cm³, one cubic metre is exactly 1,000 litres, one US gallon is exactly 3.785411784 litres, one imperial gallon is exactly 4.54609 litres, and one cubic foot is exactly 28.316846592 litres. Everything else follows by division, and the table below carries the results far enough that most conversions need only one multiplication.
| One unit of | Litres | US gallons | Cubic feet |
|---|---|---|---|
| 1 cubic metre | 1,000 | 264.172 | 35.315 |
| 1 litre | 1 | 0.264 | 0.035 |
| 1 cubic foot | 28.317 | 7.481 | 1 |
| 1 cubic inch | 0.016 | 0.004 | 0.001 |
| 1 US gallon | 3.785 | 1 | 0.134 |
| 1 imperial gallon | 4.546 | 1.201 | 0.161 |
The two worked examples on this page convert both ways. The can, 785.398 cm³, is 0.785 litres, 0.207 US gallons, 0.173 imperial gallons, 0.028 cubic feet and 47.928 cubic inches. The tank, 37.699 m³, is 37,699 litres, 9,959 US gallons, 8,293 imperial gallons and 1,331 cubic feet. The gallon trap deserves its own sentence: a US gallon and an imperial gallon differ by about 20%, so a tank quoted as 10,000 gallons holds 37,854 litres if the gallons are American and 45,461 litres if they are British — a difference of 7,607 litres, larger than many domestic tanks outright. If a supplier, a manual or a label does not say which gallon it means, the figure is not yet usable, and the safe move is to ask rather than to convert.
Lengths need the same care when they arrive in feet and inches together. The method is to reduce everything to inches first, then divide by 12: a length of 5 feet 6 inches is 66 inches, which is 66 × 2.54 = 167.64 cm. Going the other way, the can’s radius of 5 cm is 1.969 inches, or 0 feet 1.97 inches, its height of 10 cm is 3.937 inches, or 0 feet 3.94 inches, and the tank’s height of 3 m is 118.110 inches, or 9 feet 10.11 inches. The calculator itself takes one length unit for every input, so a mixed feet-and-inches measurement has to be combined before typing — or read back from the Advanced options, which show the current radius and height in feet and inches automatically. That combined reading is also the form a tape measure gives, which is why it is the form worth checking against before ordering material or cutting pipe.
Weight and cost from volume: density does the work
Volume tells you how much space a cylinder fills; density tells you how much that space weighs. Weight = volume × density, with the units matched: volume in cm³ times density in g/cm³ gives grams, and volume in m³ times density in kg/m³ gives kilograms. The densities below are typical values for ordinary material at ordinary temperatures — real batches vary, timber especially, so treat them as estimating figures and use a supplier’s datasheet where a load, a freight charge or a structural question depends on the answer.
| Material | Density (g/cm³) | Density (kg/m³) |
|---|---|---|
| Water | 1.00 | 1,000 |
| Oil (typical) | 0.90 | 900 |
| Oak (typical, dry) | 0.72 | 720 |
| Concrete | 2.40 | 2,400 |
| Glass | 2.50 | 2,500 |
| Aluminium | 2.70 | 2,700 |
| Steel | 7.85 | 7,850 |
| Copper | 8.96 | 8,960 |
The can-sized cylinder shows how large the spread is. At 785.398 cm³ it weighs 0.785 kg full of water, 2.121 kg as solid aluminium, 6.165 kg as solid steel and 7.037 kg as solid copper — the same shape, nearly nine times the weight from water to copper. A concrete column of radius 0.5 m and height 1 m has volume π × 0.25 × 1 = 0.785 m³ and weighs 0.785 × 2,400 = 1,885 kg, which is why even a modest column is a crane job, not a two-person lift. The steel pipe from the hollow-cylinder section, 11.714 kg of steel per metre, costs 23.43 per metre at a price of 2 per kg — the page shows no currency symbol here on purpose, because the price you type is in whatever currency you buy in, and the arithmetic is identical either way.
Three choices decide which volume the density multiplies. For a solid cylinder it is the full volume. For a hollow cylinder it is the wall material volume, never the bore volume — weighing the bore would price the empty space. For a liquid in a tank it is the filled volume, not the tank’s full capacity: the 37,699-litre tank at 50% holds 18,850 litres of water, which weighs about 18,850 kg, while the same tank full would weigh about 37,699 kg before the tank itself is counted. The Advanced options follow the first two rules: set a wall thickness and the weight switches to the material volume, and set a density and a price per kg to read off both the weight and the cost for your own cylinder.
Volume and surface area at a glance: a reference table
Most cylinders people actually meet are small, round numbers of centimetres, so a short reference table settles most questions without any typing. Every figure below is πr²h for volume and 2πr(r + h) for total surface area, in cm³ and cm², and every row can be checked against the calculator by entering its radius and height. The pattern to notice is the one the deep dive on this page explains: moving down a column, where the radius grows, the volume jumps far faster than the surface area, because the radius is squared in the volume but appears only once in the surface-area formula.
| Radius | Height | Volume | Total surface area |
|---|---|---|---|
| 1 cm | 5 cm | 15.708 cm³ | 37.699 cm² |
| 2 cm | 5 cm | 62.832 cm³ | 87.965 cm² |
| 3 cm | 5 cm | 141.372 cm³ | 150.796 cm² |
| 5 cm | 5 cm | 392.699 cm³ | 314.159 cm² |
| 2 cm | 10 cm | 125.664 cm³ | 150.796 cm² |
| 4 cm | 10 cm | 502.655 cm³ | 351.858 cm² |
| 5 cm | 10 cm | 785.398 cm³ | 471.239 cm² |
| 10 cm | 10 cm | 3,141.593 cm³ | 1,256.637 cm² |
One row pair in the table is a useful sanity check for any cylinder tool. A radius of 2 cm at a height of 10 cm and a radius of 3 cm at a height of 5 cm do not hold the same volume — 125.664 cm³ against 141.372 cm³ — even though their surface areas are close, and a radius of 2 cm at 5 cm height against the same radius at 10 cm height doubles the volume exactly, 62.832 cm³ to 125.664 cm³, because only the height changed. If a calculator ever disagrees with those two checks, the calculator is wrong, not the table.
Sizing a tank from measured demand, not from a guess
A tank should be sized from what is actually used, measured over days, with a reserve for the days when use is highest.
Measure first. Read the meter, or the tank level, at the same time each day for a week that includes the heaviest-use days, and the daily figures show the pattern: the average day, the peak day, and the days when nothing is used at all. The tank must cover the peak run of days between refills, not the average day, because a tank sized to the average runs dry on the first run of peak days, and the reserve is the difference between the average and the peak, carried for the longest gap between refills. A tank that is refilled daily needs only a day of peak use plus a margin; a tank refilled weekly needs a week of peak use plus a margin, and the margin is for the unexpected, a leak, a hot spell, a guest, or a delayed delivery, not for optimism about the average.
Two volumes inside the tank are not usable, and both must be allowed for. The freeboard, the space left at the top so the tank does not overflow when it is filled, is not storage, and the dead volume below the outlet, which the outlet cannot draw, is not storage either, so the nominal volume of the tank overstates the usable volume by both amounts, and the sizing should be done on the usable volume, not the nominal one. Measure the tank from the outlet height to the fill level, not from the floor to the lid, and check the result against the calculator above by entering the usable height rather than the full height. The companion guide works water-tank and fish-tank capacity in litres and gallons, with the unit conversions, so the demand figure measured here can be turned into a tank size there, in the units the supplier quotes.
Frequently asked questions
What is the formula for the volume of a cylinder?
V = πr²h: the area of the circular base (πr²) multiplied by the height. For a radius of 5 cm and a height of 10 cm that is π × 25 × 10 = 250π ≈ 785.398 cm³. Everything else on this page — surface areas, backwards solves — is built from this one formula.
How do I find the volume if I only know the diameter?
Halve the diameter to get the radius, then use V = πr²h as usual — or tap the Diameter button above and type the diameter straight in; the calculator halves it for you. A diameter of 10 cm means a radius of 5 cm, and the volume comes out identical either way: the diameter check under the calculator runs exactly this comparison on your numbers.
How do I work out the height of a cylinder from its volume?
Rearrange the formula: h = V ÷ (πr²). A cylinder that must hold 1,000 cm³ on a radius of 5 cm needs h = 1,000 ÷ (π × 25) = 12.732 cm. The Find the height mode does this and then rebuilds the volume from the height it found, as a check.
What is the surface area of a cylinder?
The total surface area is 2πr(r + h): the lateral (side) area 2πrh plus the two circular caps 2πr². For r = 5 cm and h = 10 cm the side is 314.159 cm², the caps are 157.08 cm² and the total is 471.239 cm². Use the lateral area alone when only the wall matters — a label, a wrap, a coat of paint on the side.
How many litres does a cylinder hold?
Convert its volume: divide cm³ by 1,000, or multiply m³ by 1,000. The can on this page holds 785.398 cm³ = 0.785 litres, while a tank of radius 2 m and height 3 m holds 37.699 m³ = 37,699 litres. The calculator shows the litres automatically whenever you work in centimetres or metres.
What if my cylinder is open at the top, like a bucket?
Its volume is unchanged — V = πr²h either way — but its surface area drops by one cap. This calculator totals a closed cylinder (both caps), so for an open top subtract one cap, πr², from the total surface area it shows: for r = 5 cm that is 78.54 cm² less. The lateral area needs no adjustment.
How do I find the volume of a hollow cylinder or pipe?
Use the annulus, the ring between the outer and inner circles: material volume = π × (R² − r²) × h, where R is the outer radius and r is the inner radius, the outer radius minus the wall thickness. A pipe with outer radius 5 cm, wall 0.5 cm and length 1 metre has an annulus area of π × (25 − 20.25) = 14.923 cm², so the wall material is 1,492.257 cm³ per metre, while the bore itself holds π × 4.5² × 100 = 6,361.725 cm³, or 6.362 litres, per metre. Type the wall thickness in the Advanced options below the calculator and both figures are worked out from your own cylinder.
How do I work out how full a tank is, as a percentage?
For an upright tank the percentage is the same for height and volume: a tank that is 50% full holds half its volume at half its height. The tank of radius 2 m and height 3 m on this page holds 37,699 litres when full, so at 50% it holds 18,850 litres at a depth of 1.5 m, and at 75% it holds 28,274 litres at 2.25 m. A horizontal tank behaves differently and needs the circular-segment formula, because the width of the liquid surface changes with depth: half full is still exactly 50%, but a depth of 0.5 m in a tank of radius 1 m and length 3 m is only 1,843 litres, 19.6% of its 9,425-litre capacity. The Advanced fill control on this page covers the upright case.
How many gallons are in a cubic metre, and which gallon?
One cubic metre is 1,000 litres, which is 264.172 US gallons but only 219.969 imperial gallons, because the imperial gallon (4.546 litres) is about 20% larger than the US gallon (3.785 litres). Always check which gallon a figure uses before comparing tank sizes across countries. The can on this page, 785.398 cm³, is 0.785 litres, 0.207 US gallons or 0.173 imperial gallons, and the Advanced options show the US-gallon figure for any cylinder you enter.
How do I find the weight of a cylinder from its volume?
Multiply the volume by the material’s density, in matching units: grams = volume in cm³ × density in g/cm³, or kilograms = volume in m³ × density in kg/m³. The can-sized cylinder on this page (785.398 cm³) weighs 0.785 kg full of water (density 1 g/cm³) but 6.165 kg as solid steel (density 7.85 g/cm³), and a concrete column of radius 0.5 m and height 1 m (0.785 m³ at 2,400 kg/m³) weighs 1,885 kg. For a hollow cylinder use the wall material volume, not the bore volume, and for a liquid use the filled volume. The Advanced options take a density and a price per kg and return both the weight and the cost.
How much spare capacity should a water tank have?
Enough to cover the longest gap between refills at peak use, plus a margin for the unexpected: a leak, a hot spell, a guest, or a delayed delivery. Size the tank on the peak run of days, not the average day, because a tank sized to the average runs dry on the first run of peak days, and carry the margin as usable volume, after allowing for the freeboard at the top and the dead volume below the outlet, which are not storage.
Does the shape of a tank change how much it holds at a given depth?
Yes, for any tank that is not a vertical cylinder. In a vertical cylinder the volume rises evenly with depth, because every horizontal slice has the same area, but in a horizontal cylinder, a sphere, or a tapered tank, the slices differ, so the same depth holds a different volume at different levels, and a level gauge that reads evenly is wrong. The calculator above works the full volume of a vertical cylinder; for a partly filled horizontal tank, work the volume from the geometry of the circular segment at the measured depth, or measure by filling and recording the level against known volumes.
How do I measure a tank that is already installed?
Measure the outside, and allow for the wall. Measure the circumference and divide by pi for the outside diameter, or measure the diameter directly where it is accessible, then subtract twice the wall thickness for the inside diameter, and measure the height from the outlet to the fill level for the usable height. Where the wall thickness is unknown, measure it at the outlet or the lid, or take the supplier nominal size for the model, and state the allowance, because the volume grows with the square of the radius and a small error in the diameter is a large error in the volume.