Marathon pace is the simplest number in running and the hardest to get right on the day. The calculation is one division — total time divided by distance — and it takes ten seconds. Choosing the pace is the real work: a pace taken from ambition rather than from evidence is the commonest way a marathon goes wrong, usually in the second half. This guide does the calculation first, in both directions, then shows how to set a race pace from a recent race and how to hold it when the race gets hard.

The formula: time divided by distance

Your pace is your total time divided by the distance you cover. If you run a marathon (26.219 miles) in 3 hours 30 minutes (12,600 seconds), your pace is 12,600 divided by 26.219, which is 480.6 seconds per mile — shown as 8:00 per mile. In kilometres the same run is 12,600 divided by 42.195, which is 298.6 seconds per km, shown as 4:58 per km. Speed is the flip side of pace: speed equals distance divided by time, so that same 3:30 marathon is 26.219 divided by 3.5 hours, which is 7.49 mph, or 12.06 km/h.

The formula works for any distance, because it is the same division every time: pace equals total time divided by distance, and total time equals pace multiplied by distance. The only thing that changes between distances is the number you divide by, which is why the calculator lets you pick the distance or enter a custom one.

From a goal time to a pace

Most runners start from a goal time and work backwards to the pace. Suppose your goal is a 4:00:00 marathon. Divide 14,400 seconds by 26.219 miles to get 549.2 seconds per mile, which is 9:09 per mile — the average pace every mile must hit, on average, for the goal. In kilometres that is 14,400 divided by 42.195, which is 341.3 seconds per kilometre, or 5:41 per kilometre. A 3:00:00 marathon needs 6:51 per mile (4:15 per kilometre), and a 5:00:00 marathon needs 11:26 per mile (7:06 per kilometre). The full goal-times table is in the companion pace chart.

The word to hold on to is ‘average’. A goal pace is the average pace every mile must hit, not the pace of any single mile. Most runners then train at or slightly faster than that pace for shorter workouts and use the split table to check each mile on race day — and the splits are where the average becomes a plan.

From a comfortable pace to a finish time

The other direction is just as useful: take a pace you can hold comfortably and see what it predicts. Suppose you comfortably run 9:00 per mile. Multiply 540 seconds by 26.219 miles to get 14,158 seconds, which is 3:55:58 — a sub-four-hour marathon. The same 9:00 pace gives a half marathon of 1:57:59 and a 10K of 55:55. An 8:00-per-mile pace gives a 3:29:45 marathon, and a 10:00-per-mile pace gives a 4:22:11 marathon.

That direction is the honest one for setting a goal: it starts from what you can already do, rather than from what you want to do. A pace you can hold for a long training run is evidence; a goal time is a wish. The calculator runs both directions, so check the wish against the evidence before race day.

Setting race pace from a recent race

The best evidence for a marathon pace is a recent race at a shorter distance. A half marathon is the most useful: double your half-marathon time and add about ten minutes, and the result is a realistic marathon estimate — a 1:50 half suggests a 3:50 marathon, and a 2:00 half suggests a 4:10 marathon. The ten minutes are the cost of the extra distance, the extra fatigue, and the fueling, and they are a rule of thumb, not a law: a well-trained runner loses less, and a first-timer loses more.

A 10K or a 5K works the same way, through the calculator: enter the race time and distance, and it returns the pace, which is the pace you have demonstrated rather than the pace you hope for. What a shorter race cannot tell you is how you will feel at mile 20, which is why the long run matters as much as the race: the pace you can hold for 18 or 20 miles in training is the pace you should race at, and if that pace is slower than the goal pace, the goal is the thing that should move.

What is a good marathon pace?

There is no single good pace — it depends on your training and fitness, your age, and the course. Many first-time marathoners finish between 10:00 and 12:00 per mile, which is a 4:22:11 to 5:14:38 marathon, and that is a perfectly good marathon. A 9:00-per-mile pace is a 3:55:58 marathon; an 8:00-per-mile pace is a 3:29:45 marathon; a 7:00-per-mile pace is a 3:03:32 marathon. The range is wide because the runners are wide, and the pace that is ‘good’ is the one that matches your training.

Average pace is the total time divided by the total distance over the whole run — including the slow miles, the walk breaks, and the uphill — which is why it is the number that matters for a finish time. Your fastest mile is not your average pace, and planning a race on your fastest mile is how a marathon goes wrong in the second half.

Holding the pace on race day

Even splits mean every mile at the same pace. They are easy to follow and easy to check with a watch, and they are the safest plan for a first marathon. A negative split means the second half is faster than the first: in this calculator the negative-split option runs the first half about 2 percent slower than your average pace and the second half fast enough that the total finish time is unchanged. For a 3:30 marathon that is roughly 8:10 per mile for the first half and 7:50 per mile for the second half.

A negative split feels harder late in the race, which is why many runners practice it in training before trying it on race day — and why starting too fast is the mistake it is designed to prevent. The first miles feel easy, but every second gained early is often paid back twice late in the race, when the glycogen runs low and the legs go. The discipline is to run the first half at the planned pace even when it feels too slow.

Mistakes that break a race plan

First, starting too fast: the first miles feel easy, but every second gained early is often paid back twice late in the race. Second, using rounded distances: a marathon is 26.219 miles, not 26 miles, and using 26 miles instead of 26.219 understates the pace needed by about half a second a mile — small, but it adds up to twenty seconds over the race. Third, planning on a fastest mile rather than an average pace: the average is what the clock measures, and the average includes the slow miles.

Fourth, ignoring the course and the weather. A hilly course, a hot day, or a crowded start all cost time the pace calculation does not know about, and the chart is a plan for a flat course on a cool day. Adjust the goal for the day you have, not the day you trained for, and the pace you choose will be one you can actually hold.

Frequently asked questions

How do I calculate marathon pace?

Divide your total time by the distance. A 3:30:00 marathon is 12,600 seconds divided by 26.219 miles, which is 480.6 seconds per mile, shown as 8:00 per mile. In kilometres, divide by 42.195: 12,600 divided by 42.195 is 298.6 seconds per km, or 4:58 per km. The Marathon Pace Calculator does the division for any time and distance you enter.

How do I calculate marathon pace from a half marathon?

Double your half-marathon time and add about ten minutes, then divide by the marathon distance. A 1:50 half marathon doubles to 3:40, plus ten minutes is 3:50, which over 26.219 miles is about 8:46 per mile. The ten minutes are a rule of thumb for the extra distance and fatigue, not a law — a well-trained runner loses less, and a first-timer loses more.

How do I calculate marathon pace from a 5K?

Enter the 5K time in the calculator and it returns the pace you demonstrated, then use that pace as the starting point for a marathon estimate. A 5K pace is faster than a marathon pace — nobody holds 5K pace for 26 miles — so treat the 5K pace as an upper bound on your fitness, not as your marathon pace, and set the marathon pace from a half marathon or a long run where possible.

What is a good marathon pace per km?

It depends on your training and fitness. Many first-time marathoners finish between 10:00 and 12:00 per mile, which is 6:12 to 7:27 per kilometre. A 9:00-per-mile pace is 5:35 per kilometre and a 3:55:58 marathon; an 8:00-per-mile pace is 4:58 per kilometre and a 3:29:45 marathon. Pick a pace you can hold in long training runs.

How fast should my long runs be?

Slower than your race pace. The long run builds endurance, not speed, so it should be run at a conversational pace — a pace at which you can talk in full sentences — which is usually 30 to 60 seconds per mile slower than marathon pace. If you cannot talk, you are running the long run too fast, and the fatigue will cost you the week’s other training.

What does average pace mean in running?

Average pace is your total time divided by your total distance over the whole run, including the slow miles, the walk breaks, and the uphill. It is the number that decides a finish time: a marathon at an average of 9:00 per mile finishes in 3:55:58 whatever the individual miles looked like. Your fastest mile is not your average pace.

Distances are the standard course lengths: marathon 26.219 miles (42.195 km), half marathon 13.109 miles (21.098 km), 10K 6.214 miles (10 km), 5K 3.107 miles (5 km).