Running Pace Calculator

How to use this running pace calculator

A running pace calculator turns any two of distance, time and pace into the third. That is the whole idea. What you do with it depends on which box you leave empty, and the three ways people use it are quite different from each other.

Every result comes back in minutes per mile and minutes per kilometre at the same time, plus miles per hour and kilometres per hour for treadmill work, plus a 400 metre lap time for track sessions. You never have to pick a unit system and then convert by hand.

How running pace is calculated

Pace is simply time divided by distance, expressed as how long one unit of distance takes. Speed is the same relationship the other way up, distance divided by time. Both describe the identical run.

A worked example. A four hour marathon covers 42.195 km, which is 26.22 miles. Four hours is 14,400 seconds. Divide by 26.22 and you get 549 seconds per mile, which is 9:09 per mile. Divide 14,400 by 42.195 instead and you get 341 seconds, or 5:41 per kilometre. Both are the same run described in different units.

Two details make this less tidy in practice than it looks. First, the mile is defined as exactly 1,609.344 metres, so a marathon is 26.2188 miles rather than a round 26.2, and rounding early moves your pace by a couple of seconds. This calculator does all the arithmetic in metres per second and rounds only at the very end. Second, the official marathon distance has been 42.195 km since it was standardised in 1921, and the half marathon is exactly half that at 21.0975 km, so those are the figures used here rather than approximations.

Marathon pace chart

This marathon pace chart shows the pace you need to hold for common finish time targets, in both units, with the halfway split you should hit if you are running even splits. Find your goal in the left column and the rest of the row is your race plan.

Two of these come up constantly. A four hour marathon needs 9:09 per mile or 5:41 per kilometre. A 3:30 marathon needs 8:01 per mile or 4:59 per kilometre, which is why so many training plans talk about breaking five minutes per kilometre. At the sharp end, a two hour marathon requires 4:35 per mile held for the whole distance.

Half marathon pace chart

The same idea over 21.0975 km. Half marathon pace is usually a little quicker per mile than marathon pace for the same runner, because the distance is short enough to hold a harder effort.

A two hour half marathon works out at 9:09 per mile, exactly the same pace as a four hour marathon. That is not a coincidence: the marathon is twice the distance and four hours is twice two hours, so the pace has to match. It is also a useful sanity check on any goal. If holding 9:09 for thirteen miles feels like a hard race day effort, a four hour marathon at that same pace is probably not realistic yet.

10K and 5K pace charts

Shorter races are where pace discipline matters most, because there is no time to recover from going out too hard. These two charts cover the usual range of finish times.

10K pace chart

5K pace chart

A fifty minute 10K is 8:03 per mile or 5:00 per kilometre. A thirty minute 5K is 9:39 per mile or 6:00 per kilometre. Those two round kilometre numbers, five minutes and six minutes, are the mental anchors most runners outside the United States actually use.

Race pace calculator: predicting your times at other distances

If you know one recent race result, you can estimate what you would run at other distances. The standard method is Riegel's formula, published by Peter Riegel in American Scientist in 1981:

What the 1.06 exponent actually means

If pace held perfectly steady as distance grew, the exponent would be 1.0 and doubling the distance would exactly double your time. It does not. The 1.06 exponent says that doubling the distance multiplies your time by about 2.085, so you lose roughly four percent of pace each time the distance doubles. That single number is the entire model of human endurance decline in this formula.

A worked race prediction

Take a 25:00 5K. Feeding that into the formula gives these predictions:

Where race predictions go wrong

Riegel himself scoped the formula to efforts lasting roughly 3.5 to 230 minutes, which covers about 1500 metres up to the marathon. Outside that window it drifts. The calculator above flags any prediction that falls outside the range rather than presenting it as if it were as reliable as the rest.

The bigger limitation is not mathematical. The formula assumes you are equally well trained for every distance it predicts. A runner who races 5K every weekend and has never run beyond ten miles will not hit the marathon time it produces, because the prediction describes a version of them that did the long runs. Treat a marathon predicted from a 5K as a ceiling, not a target.

The Magic Mile: predicting race pace from one hard mile

The Magic Mile is Jeff Galloway's field test. You warm up, run one mile as hard as you can hold evenly, and then apply his published conversions to get your race paces. It is the cheapest fitness test in running: no lab, no race entry, about fifteen minutes including the warm up.

How the Magic Mile conversions work

Galloway's conversions are applied to the mile time to give a race pace per mile. For a 5K you add 33 seconds. For everything else you multiply: 1.15 for a 10K, 1.175 for ten miles, 1.2 for a half marathon and 1.3 for a marathon.

Magic Mile compared with Riegel

The two methods answer the same question from different data. Riegel needs a recent race at a real distance and extrapolates from it. The Magic Mile needs only a mile, which almost anyone can do on a track next week, but it is calibrated for Galloway's run walk approach and it assumes cool conditions, around 60°F or below. Where they disagree, trust the one built on the effort closest in length to the race you are planning.

Pace, speed and distance conversions

Half the questions people bring to a running pace calculator are really unit conversions. These two tables answer the common ones without any input at all.

Race distances in kilometres and miles

The two that get searched most are the 8K, which is 4.97 miles, and the 3K, which is 1.86 miles. Both are close enough to five miles and two miles that people assume they are the same and then wonder why their pace maths does not work out.

Treadmill speed to running pace

Treadmills show speed, races are run at a pace, and the two are the same thing expressed differently. This table converts between them, including how far you cover in one hour at each setting.

So 5 mph is a 12:00 mile, and 7 mph is an 8:34 mile or 5:20 per kilometre. One caveat that most treadmill charts skip: a treadmill belt moves under you and there is no air resistance, so the same displayed speed is slightly easier than running that pace outdoors. Setting the incline to one percent is the usual correction for that difference.

What is a good running pace?

There is no single good running pace, and any page that gives you one number is guessing. Pace depends on age, training history, body size, terrain, heat, altitude and what the run is for. A pace that is a comfortable warm up for one runner is a hard race effort for another, and both are correct.

A more useful question is whether your pace matches the purpose of the run. That has an answer you can check without any data at all.

If you want a concrete benchmark rather than a feeling, use the charts on this page in reverse. Pick a finish time that would genuinely please you, read off the pace, then go and run one mile at it. Whether that mile felt like a jog or like a race tells you more about whether the goal is right than any average pace figure could.

Even splits, negative splits and how to pace a race

The split table in the calculator above defaults to even pacing, where every kilometre or mile takes the same time. You can switch it to a negative split, where the second half is deliberately run quicker than the first. The total time stays identical either way, which is the point: it is the same race, distributed differently.

Why the second half is the one that decides your time

Almost every finish time that disappoints its owner was lost in the second half, not the first. Going out thirty seconds a mile too quick feels effortless for four miles and costs several minutes over the last six. A negative split plan protects against that by making the first half feel slightly too easy on purpose.

How much of a negative split is realistic

One to three percent is a reasonable planning range, which is what the calculator offers. On a 4:00 marathon plan, a two percent negative split means starting at 9:15 per mile instead of 9:09 and finishing at 9:04. Those are small enough numbers to actually execute. Plans that call for a ten percent negative split usually just mean the first half was run too slowly.

When even splits are the better plan

On a flat course in cool weather, even pacing is hard to beat and much easier to hold. Save the negative split plan for a hot day, a hilly first half, or a distance you have not raced before, where starting conservatively buys you information about how the day is going.

When a pace calculator gets it wrong

A running pace calculator does exact arithmetic on the numbers you give it. It knows nothing about the day you will actually have. These are the factors that move real finish times away from the calculated one.

Running pace calculator FAQ

Sources and limits

The race prediction model is Peter Riegel's endurance formula, published in American Scientist in 1981, using the 1.06 exponent and the stated validity window of roughly 3.5 to 230 minutes. The Magic Mile conversions are the ones published on Jeff Galloway's own site. Official race distances follow World Athletics, which puts the marathon at 42.195 km, standardised in 1921. The mile and the yard are used at their exact international definitions of 1,609.344 metres and 0.9144 metres.

Everything here is arithmetic and estimation, not coaching advice specific to you. Predicted times assume appropriate training for the distance and reasonable conditions on the day. See our calculator accuracy policy for how these formulas were checked.