Cubic Feet Calculator – Volume in Cubic Feet for Boxes, Rooms & Loads
Measure a box once and read its volume every way you need it: cubic feet, cubic inches, cubic yards, gallons and liters — for one box, a cylinder, or a whole stack of moving boxes, with a running total and the shipping cost per cubic foot.
Box dimensions
Cylinder dimensions
Your load — box by box
Up to five different boxes. Leave a row empty to skip it — the total only counts rows you fill in.
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Box volume
Cylinder volume
Total load volume
See the box
Your box, drawn to its three dimensions. The orange fill scales with the volume — measured against a 12 ft cube room (1,728 ft³), so a single moving box is a thin layer at the bottom, exactly as it should be.
Your box: 24 x 18 x 18 in = 4.50 ft³ total. The orange fill scales the volume against a 12 ft cube room (1,728 ft³).
- Each side is converted to feet first, then multiplied, so mixed-unit mistakes never happen; one cubic foot is exactly 1,728 cubic inches.
- One box, a cylinder, or a whole load: the multi-box list totals up to five different boxes.
- Read it every way at once — cubic feet, inches, yards, meters, gallons and liters, plus the cost at any price per cubic foot.
Keep exploring
Three companion tools for space, area and materials.
How it works
Three steps from a tape measure to every unit at once.
Measure the three sides
Length, width and height — in inches, feet or metric. For boxes you will fill or ship, measure the inside if the contents matter, the outside if the space it must fit into matters.
We convert, then multiply
Each side is converted to feet first, then multiplied — so mixed-unit mistakes never happen. One cubic foot is exactly 1,728 cubic inches, and every other unit follows from there.
Read it every way
Cubic feet up top, then inches, yards, meters, gallons and liters — plus quantity totals, a whole load in the multi-box list, and the cost at any price per cubic foot.
The math behind cubic feet
A cubic foot is the volume of a cube one foot on every side. Any box-shaped space gets there the same way: multiply the three sides. Measure in inches and the answer comes out in cubic inches — divide by 1,728 (12 × 12 × 12) to turn it into cubic feet. That single number, 1,728, is why every conversion on this page is exact rather than approximate.
Worked example — a large moving box, 24 × 18 × 18 inches:
| Step | Working | Result |
|---|---|---|
| Multiply the sides | 24 × 18 × 18 | 7,776 in³ |
| Convert to cubic feet | 7,776 ÷ 1,728 | 4.50 ft³ |
| The same volume, other units | 4.50 ÷ 27 · 4.50 × 7.48052 · 4.50 × 28.3168 | 0.1667 yd³ · 33.66 gal · 127.43 L |
Cylinder check: a round tank 2 ft across and 3 ft tall has radius 1 ft, so π × 1² × 3 = 9.42 ft³ — the Cylinder tab works this out for any diameter and height, in any unit.
One cubic foot, every way: 1,728 in³ · 0.037037 yd³ · 0.0283168 m³ · 28.3168 liters · 7.48052 US gallons. Tape-measure people think in inches, movers in cubic feet, concrete crews in cubic yards and tank owners in gallons — it is the same space, five languages.
Go deeper
Box sizes, a full storage-unit example, and how freight pricing uses cubic feet.
The boxes every moving company sells, with their true volumes. Notice how fast it adds up: a wardrobe box holds as much as twelve small boxes.
| Box | Size (in) | Cubic feet |
|---|---|---|
| Small | 16 × 12 × 12 | 1.33 ft³ |
| Medium | 18 × 18 × 16 | 3.00 ft³ |
| Large | 24 × 18 × 18 | 4.50 ft³ |
| Extra-large | 24 × 18 × 24 | 6.00 ft³ |
| Dish pack | 18 × 18 × 28 | 5.25 ft³ |
| Wardrobe | 24 × 24 × 48 | 16.00 ft³ |
Tap a preset chip in the Box tab to load any of the four most common sizes, or add your own mix in the multi-box list.
A standard 10 × 10 storage unit with an 8 ft ceiling holds 10 × 10 × 8 = 800 ft³ of gross space. In large moving boxes that is 800 ÷ 4.50 ≈ 177 boxes — but no real load packs perfectly:
- Usable space is roughly 70% once furniture shapes, walkways and stacking gaps are counted — about 560 ft³ of actual goods, or roughly 124 large boxes.
- A studio apartment typically runs 400–600 ft³ of boxed goods — right at the limit of a 10 × 10 unit, which is why the multi-box total matters before you rent.
- Ceiling height is the hidden variable: the same 10 × 10 unit with a 10 ft ceiling holds 1,000 ft³ — 25% more space for often the same money.
Total your load in the multi-box tab, then compare it with the unit’s floor size × ceiling height before signing anything.
Freight carriers shorten cubic feet to CFT, and volume is often the price — not weight:
- Ocean and LTL freight are commonly quoted per CFT, which is what the price-per-cubic-foot field in the Box tab is for: 4.50 ft³ at $12/ft³ costs $54.00.
- Dimensional weight: parcel carriers also convert volume into a billable weight (in inches, L × W × H ÷ a divisor such as 139) and charge whichever is higher — big, light boxes cost more than their scale weight suggests.
- Measure outside for shipping: carriers measure the outside of the box, bulges included, and round up — a box taped generously can bill a size larger than the one you packed.
Measuring right the first time
Volume math is exact. Measurement is where the errors creep in, so measure like the answer matters, because it does.
Start with the question the measurement has to answer. If you are filling a box, measure the inside: the contents live inside the walls, and the usable volume is smaller than the outside by the thickness of the cardboard or timber on every side. If you are fitting a box into a truck, a shelf, or a storage unit, measure the outside: the space it must fit into does not care what is inside. If you are ordering a material to fill a space, measure the space itself, not the container it arrives in. Most cubic-feet mistakes are not arithmetic mistakes at all. They are answers to the wrong question, computed perfectly.
Measure each side at its longest point, and measure twice when the sides are not square. A box that bulges, a room with a bay, a tank with a domed top — none of these is a single clean box, and pretending otherwise understates or overstates the volume by the awkward part. The honest method is to break an irregular shape into boxes and cylinders you can measure, compute each part, and add them. A room shaped like an L is two rectangles, not one. A wardrobe box with a hanging bar is a box plus nothing, because the bar takes almost no volume, but a room with a built-in closet is a room plus a closet, and the closet deserves its own three measurements. The multi-box tool on this page exists for exactly this: up to five boxes, each with its own dimensions and quantity, summed into one load figure.
Keep the units consistent before you multiply, and let the calculator do the conversion. Inches, feet, and centimetres can all appear on the same tape measure, and mixing them is the classic error: a box measured as 24 by 18 by 18 in one unit and entered as if it were another comes out wrong by a factor of twelve, or of 1,728, and no later rounding fixes it. Enter each side in the unit you measured it in, and check the converted result before trusting it. A large moving box should come out near 4.50 cubic feet. A room 12 feet by 10 feet with an 8-foot ceiling should come out at 960 cubic feet. If your answer is wildly larger or smaller than that kind of landmark, a unit has been mixed, and the fix is in the inputs, not in the formula.
Finally, round at the end, not in the middle. The calculator carries exact balances through every conversion, and rounding each side to a whole number before multiplying can shift a large load by several cubic feet. Measure to the nearest half inch for boxes and the nearest inch for rooms, enter what you measured, and let the displayed result carry the rounding. For ordering materials, round up to the next whole unit the supplier sells — a cubic yard short is a second delivery, while a cubic yard over is a small pile you can use elsewhere.
Cubic feet in the real world: trucks, units, tanks, and freight
The same number prices a move, sizes a unit, fills a tank, and bills a shipment. Each trade reads it differently.
For a move, the load total is the number that matters. Add every box, every piece of furniture measured as its bounding box, and every appliance the same way, and the sum is the volume the truck must hold. A 10-foot by 10-foot storage unit with an 8-foot ceiling holds 800 cubic feet in theory, and 177 boxes of the 4.50-cubic-foot large size would fill that arithmetic exactly. In practice it holds fewer, because boxes do not pack perfectly, aisles and doors take space, and furniture wastes the corners that boxes would fill. Treat the arithmetic as a ceiling, not a promise, and leave a margin of a fifth or so when choosing a unit or a truck from a volume total. The load tool on this page gives you the exact sum; your judgement supplies the margin.
For bulk materials, cubic feet are a stepping stone to cubic yards, because that is the unit suppliers sell in. One cubic yard is a cube 3 feet on every side, so it holds 27 cubic feet, and every bulk order divides by 27. A slab 10 feet by 12 feet and 4 inches deep is 40 cubic feet, which is 1.48 cubic yards, so you order 2 cubic yards and accept the spare, because a short order stops the pour. The same division serves soil, mulch, and gravel, with one caution: loose materials settle and spread unevenly, so a depth measured in one corner is not the depth everywhere. Measure depth in several places and use the average, and the yardage will be closer to what the ground actually takes.
For tanks and containers, cubic feet translate directly into liquid capacity, because one cubic foot holds 7.48052 US gallons. The cylinder tool on this page already shows both: a tank 2 feet across and 3 feet tall holds 9.42 cubic feet, which is about 70.5 gallons. The same conversion sizes aquariums, rain barrels, ponds, and planters, with the same inside-versus-outside caution as boxes: a tank’s stated capacity is its inside volume, and a wall thickness of even half an inch on every side removes a noticeable share from a small container. For a pond or a raised bed, the shape is rarely a clean box or cylinder, so break it into sections, as with rooms, and add the parts.
For freight, cubic feet are the starting point, not the bill. Carriers price from the volume of a shipment as well as its weight, and they measure the outside of each box and often round up. They then apply their own dimensional-weight formula, which varies by carrier and by service, and this page deliberately states no carrier divisor, because a divisor quoted here would be wrong for some carrier, some service, or some date. What this page gives you is the exact actual cubic feet, measured the way carriers measure, so that any carrier’s formula can be applied to a correct input. If a quote surprises you, check the carrier’s measured dimensions against yours first: a box measured one inch larger on every side by the carrier is a larger volume, and that difference, not the rate, is usually the explanation.
Conversion reference, worked from one number
Every conversion on this page follows from 1,728 cubic inches in a cubic foot. The table below is that fact, unfolded.
A cubic foot is a cube one foot on every side. A cubic yard is a cube three feet on every side, so it contains 3 times 3 times 3, or 27, cubic feet. A cubic metre is larger still: one metre is 3.28084 feet, and cubing that gives 35.3147 cubic feet in a cubic metre. Going the other way, a US gallon occupies 0.133681 cubic feet, so one cubic foot holds 7.48052 gallons, and a litre occupies 0.0353147 cubic feet, so one cubic foot holds 28.3168 litres. None of these numbers needs memorising if you remember the two anchors, 1,728 and 27, because every other conversion is a division or a multiplication away, and the calculator on this page performs all of them at once.
| One unit | In cubic feet | One cubic foot in that unit |
|---|---|---|
| 1 cubic inch | 0.0005787 ft³ | 1,728 in³ |
| 1 cubic yard | 27 ft³ | 0.037037 yd³ |
| 1 cubic metre | 35.3147 ft³ | 0.0283168 m³ |
| 1 US gallon | 0.133681 ft³ | 7.48052 gal |
| 1 litre | 0.0353147 ft³ | 28.3168 L |
Three worked landmarks are worth keeping beside the table. A box 36 inches by 24 inches by 24 inches holds 20,736 cubic inches, which is exactly 12 cubic feet, or 0.4444 cubic yards, or about 89.77 US gallons. A room 12 feet by 10 feet with an 8-foot ceiling holds 960 cubic feet of air, which is why ceiling height matters so much to heating and cooling: the same floor area with a 10-foot ceiling holds 1,200 cubic feet, a quarter more air to condition. And a cylinder 3 feet across and 4 feet tall holds 28.27 cubic feet, because the radius is 1.5 feet and pi times 1.5 squared times 4 is 28.27. Each of these can be checked in the calculator on this page, and each one is a quick sanity check for any measurement of your own: if your box, room, or tank is near one of these sizes and your answer is far away, re-measure before you trust it.
Five mistakes that make a right formula give a wrong answer
Every one of these has shipped a wrong order, a truck too small, or a tank that overflowed. All five are preventable.
The first mistake is confusing square feet with cubic feet. Area is length times width, and it answers how much floor or wall you have. Volume is length times width times height, and it answers how much space or material you have. A room 12 feet by 10 feet is 120 square feet of floor, but with an 8-foot ceiling it is 960 cubic feet of air, and ordering materials, sizing heaters, or choosing a storage unit from the area figure alone understates the job by the whole height dimension. If your answer has no height in it, it is an area, not a volume, no matter what the label on the result says.
The second mistake is using the diameter where a radius belongs. A cylinder’s volume uses the radius squared, and the radius is half the diameter, so entering the full diameter quadruples the answer: pi times diameter squared is four times pi times radius squared. The cylinder tool on this page asks for diameter and halves it for you, which is why its default of 2 feet across and 3 feet tall gives 9.42 cubic feet and not 37.70. Whenever you compute a cylinder by hand, halve the diameter first, and check the result against a landmark: a cylinder about as wide as it is tall holds roughly three quarters of the box that would contain it, because pi divided by 4 is 0.785.
The third mistake is mixing US and imperial gallons. This page uses US gallons, as American suppliers, movers, and carriers do: one cubic foot holds 7.48052 US gallons. An imperial gallon, used in the United Kingdom, is larger, at 0.160544 cubic feet each, so one cubic foot holds only 6.22884 imperial gallons. A tank quoted at 100 imperial gallons holds about 120 US gallons, and a conversion done with the wrong gallon is wrong by a fifth. If a specification comes from outside the United States, check which gallon it means before converting, and convert through cubic feet, which do not change between countries.
The fourth mistake is treating volume as weight. A cubic foot of feathers and a cubic foot of concrete occupy the same space and weigh vastly different amounts, and a truck, a shelf, or a floor has a weight limit as well as a volume limit. Cubic feet answer the space question only. If the load is dense, check the weight separately: concrete runs about 150 pounds per cubic foot, water about 62.4 pounds per cubic foot, and a volume that fits easily can still overload the vehicle carrying it. The two limits are independent, and satisfying one does not satisfy the other.
The fifth mistake is forgetting what is already in the space. A storage unit that already holds shelving, a room with a large wardrobe, a tank with a filter and substrate inside — each of these has less usable volume than its bare dimensions suggest. The honest method is to measure the space, subtract the volume of anything permanent inside it, and only then compare with the load. For a tank, that means the water volume is the inside volume minus rocks, substrate, and equipment. For a room, it means usable storage is the room minus the furniture that stays. A calculator can only multiply the numbers it is given, so give it the numbers for the space you actually have, not the space the walls describe.
Square feet to cubic feet: the missing third number
Square feet measure area, and cubic feet measure volume, and no arithmetic converts one to the other without a third number: the depth or height. Volume is area times height, so a room of 200 square feet with an 8-foot ceiling holds 1,600 cubic feet of air, and the same 200 square feet with a 10-foot ceiling holds 2,000. The depth must be in the same unit as the area’s sides, feet with square feet, and the answer is only as good as the depth entered, which is why a slab, a fill, and a room each need their own depth, and why a bare area figure, without a depth, cannot be priced, ordered, or moved.
Coverage questions run the same formula backwards, and they are where the missing depth causes the most confusion. Asking how many square feet 3 cubic feet covers has no answer until a depth is named: at 3 inches deep, which is a quarter of a foot, 3 cubic feet covers 12 square feet, because 3 divided by 0.25 is 12; at 6 inches deep it covers 6. A concrete example keeps the units honest: a slab 100 square feet in area and 4 inches thick, a third of a foot, needs 100 times one third, which is 33.3 cubic feet. State the depth with every area-to-volume conversion, in the same unit, and the conversion stops being a guess.
Measuring for real spaces: rooms, fridges, and moving loads
Measure the space you will actually use, not the space the walls describe. For a room, measure inside wall to inside wall, at the longest points, and record length, width, and ceiling height in one unit before multiplying; for an L-shaped room, split the floor into two rectangles, work each volume separately, and add them, rather than multiplying the longest length by the longest width, which counts the missing corner twice. Measure twice, in the same unit, and write the numbers down, because a tape read in inches and entered as feet is the commonest measuring error on this page, and it is wrong by a factor of twelve.
Two spaces need their own care. A refrigerator’s stated capacity is the manufacturer’s inside volume, measured with the shelves and fittings in their usable positions, so measuring the outside of the cabinet and multiplying will always overshoot it, and the outside measurement is the one to use only for whether the unit fits the gap. A moving load is measured the other way: add the bounding-box volume of each box and each piece of furniture, then allow for the gaps between irregular shapes, because boxes do not tessellate perfectly and a load estimated at exactly the truck’s volume will not fit. The calculator multiplies the numbers it is given; the measuring decides whether those numbers describe the space you have.
Frequently asked questions
Quick answers about cubic feet.
How do I calculate cubic feet?
Multiply length by width by height. If all three sides are in feet, the answer is already in cubic feet. If they are in inches, the answer is in cubic inches — divide by 1,728 to get cubic feet. For a large moving box: 24 × 18 × 18 = 7,776 cubic inches, and 7,776 ÷ 1,728 = 4.50 cubic feet.
How do I convert inches to cubic feet?
Two equivalent ways: divide each side by 12 to get feet, then multiply — or multiply the inches first and divide the total by 1,728. Either route gives the same answer because a cubic foot is a 12-inch cube: 12 × 12 × 12 = 1,728 cubic inches. This calculator does it automatically when Inches is selected.
What is the difference between cubic feet and cubic yards?
Only the size of the cube: a cubic yard is a 3 ft cube, so it holds 3 × 3 × 3 = 27 cubic feet. Divide cubic feet by 27 to get cubic yards. Cubic yards are the language of bulk materials — concrete, mulch, gravel and soil are sold by the yard — while cubic feet suit boxes, rooms and appliances.
How many gallons are in a cubic foot?
One cubic foot holds 7.48052 US gallons — and 28.3168 liters. That is why a 4.50 ft³ moving box, if it were a tank, would hold about 33.66 gallons. The gallon and liter figures are shown on every calculation here because tank and aquarium volumes are usually quoted in gallons, not cubic feet.
What does CFT mean in shipping?
CFT is simply the freight industry’s abbreviation for cubic feet. Ocean freight, LTL trucking and many storage facilities price by the CFT: total up the cubic feet of every box (the multi-box tab does this) and multiply by the quoted rate per cubic foot to get the volume charge. Carriers measure the outside of each box and often round up.
Why would I need the cubic feet of a room?
Because air has volume too. Air conditioners and heaters are sized partly by room volume — a 12 × 12 ft room with a 10 ft ceiling holds 1,440 cubic feet of air, a third more than the same room with 8 ft ceilings. Room volume also drives air-purifier and fan sizing, paint and odor coverage estimates, and how much storage a room or unit really offers.
How do I calculate cubic feet for a cylinder?
Use pi times the radius squared times the height, with every measurement in feet. The radius is half the diameter, so a tank 2 feet across has a radius of 1 foot, and at 3 feet tall it holds pi times 1 squared times 3, which is 9.42 cubic feet. If you measured in inches, convert first: divide the diameter and the height by 12 to get feet, then apply the same formula. The cylinder tool on this page does this for you, and also shows the result in gallons, because one cubic foot holds 7.48052 US gallons.
How many cubic feet are in a cubic yard?
27. A cubic yard is a cube 3 feet on every side, so it holds 3 times 3 times 3 cubic feet. To convert cubic feet to cubic yards, divide by 27. A slab 10 feet by 12 feet and 4 inches deep is 40 cubic feet, which is 1.48 cubic yards, so you would order 2 cubic yards. Cubic yards are the unit bulk suppliers use for concrete, soil, mulch, and gravel, while cubic feet suit boxes, rooms, and tanks.
Should I measure the inside or the outside of a box?
It depends on the job. Measure the inside when the contents matter: filling a box, sizing a tank, or working out what a container holds. Measure the outside when the space matters: fitting boxes into a truck, a shelf, or a storage unit, or when a carrier prices the shipment, because carriers measure the outside and often round up. Manufacturer box dimensions are usually outside measurements, so the usable inside volume is slightly smaller. If you are unsure which one a quote or a specification uses, ask, because the difference is the wall thickness on every side.
How do I estimate a whole room or a moving truck load?
Add the parts. For a room, multiply length by width by height, breaking an L-shaped or irregular room into rectangles first and adding them. For a load, measure each box and each piece of furniture as its bounding box, multiply out each one, and add the totals: the multi-box tool on this page does this for up to five box types with quantities. Then leave a margin. Boxes do not pack perfectly and furniture wastes corners, so a truck or unit chosen from the exact arithmetic alone will feel tight. Treat the summed volume as the minimum space you need, not as a guarantee that everything will fit.
Can you convert cubic feet to square feet directly?
No. Cubic feet measure volume and square feet measure area, and the conversion needs a third number: the depth or height. Volume is area times height, so 200 square feet with an 8-foot ceiling is 1,600 cubic feet. A coverage question, how many square feet a volume covers, likewise needs a depth: 3 cubic feet at 3 inches deep covers 12 square feet.
How do I measure the cubic feet of a refrigerator?
Use the manufacturer’s stated inside capacity where it is printed on the rating label or the specification sheet, since that is the usable inside volume. If you measure it yourself, measure inside wall to inside wall, width, height, and depth, in inches, multiply, and divide by 1,728 to get cubic feet, and expect a figure below the outside dimensions, because the walls, shelves, and fittings take up space.
How do I measure an L-shaped room in cubic feet?
Split the floor plan into two rectangles, measure each rectangle’s length, width, and the ceiling height, work out each volume separately, and add the two volumes. Do not multiply the longest length by the longest width, which counts the missing corner as if it were room. Measure inside wall to inside wall, in one unit throughout, and measure twice.
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Disclaimer
This calculator is for information and planning only. Box dimensions printed by manufacturers are usually outside measurements, so the usable inside volume is slightly smaller; carriers and storage facilities measure and round by their own rules, and their figures govern any bill. Verify freight quotes and unit sizes with the provider before booking.