Give this calculator any two of pace, time and distance and it returns the third instantly, in both min/km and min/mile alongside speed in kph and mph. Pick a race preset or enter a custom distance, then get a full split table at kilometre, mile, 5K or 400m track-lap intervals with your choice of even, negative or positive pacing. It also predicts your equivalent finish times at every other standard race distance using Riegel's formula, so a recent 10K result tells you what half marathon to target. Pair it with the heart rate zone calculator to match effort to pace, or the TDEE calculator for the fuelling side.
Pace Calculator
Pace, time or distance from the other two — with a printable split table and your predicted time at every race distance.
Finish time
Pace
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Per kilometre—
Per mile—
Speed—
Distance—
Splits
Equivalent times at other distances
Predicted with Riegel's formula — assumes you are trained for the distance.
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Pace, time and distance
The three quantities are locked together: pace = time ÷ distance, so knowing any two gives you the third. Pace is expressed as time per unit distance (5:00 per km means each kilometre takes five minutes), while speed is the inverse — distance per unit time. Runners think in pace, cyclists in speed, and this calculator shows both.
Splits and why they matter
A split is the time for each segment of a race. Knowing them in advance is what stops the single most common racing mistake: going out too fast. Adrenaline at the start makes goal pace feel absurdly easy, runners bank time they think they will keep, and then pay it back with interest in the closing miles. A printed or memorised split sheet gives you an objective check at every marker.
Even, negative and positive splits
An even split runs identical pace throughout and is the most energy-efficient approach for most runners — analysis of world records at long distances shows the fastest times almost always come from near-even pacing. A negative split runs the second half slightly faster than the first, typically by 1–3%; it is the safest strategy for the half marathon and marathon because it conserves glycogen early and protects against hitting the wall. A positive split — fast start, slower finish — is what most amateurs do accidentally, though it is a deliberate and reasonable choice in middle-distance track events like the 800m.
Predicting times at other distances
The equivalent times above use Riegel's formula: T₂ = T₁ × (D₂ ÷ D₁)^1.06. The exponent 1.06 encodes the fact that pace inevitably slows as distance grows — you cannot hold 5K pace for a marathon. It is accurate to within a few percent for trained runners predicting between 5K and the marathon.
Two caveats. It assumes you have actually trained for the target distance: a strong 5K runner with no long runs will not hit their predicted marathon, because endurance is a separate adaptation from speed. And it gets less reliable the further you extrapolate — predicting a marathon from a 1500m time is close to guesswork.
What the calculator cannot know
Pace maths assumes constant conditions. Heat and humidity can cost 20–30 seconds per mile or more, hills cost more going up than they return coming down, headwind is a real tax, and altitude reduces aerobic capacity until you acclimatise. Build a buffer into any goal set on a flat cool day if race day will not be one. Heart rate is a useful cross-check because it responds to the actual physiological load rather than the clock — the heart rate zone calculator covers that side.
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Frequently asked questions
How do I calculate running pace?
Divide total time by distance. A 50-minute 10K is 50 ÷ 10 = 5:00 per kilometre. To convert to miles, multiply the per-km pace by 1.609 — so 5:00/km is about 8:03/mile. This calculator does both directions and handles the minutes-and-seconds arithmetic for you.
What is a negative split and should I use one?
It means running the second half of a race faster than the first, usually by 1–3%. For the half marathon and marathon it is the safest strategy — starting slightly conservative preserves glycogen and protects against a late collapse. For short track races a fast start is often better.
How accurate is the race time predictor?
Riegel's formula is typically within 2–5% for trained runners predicting between 5K and marathon from a recent all-out result. It assumes you have trained specifically for the target distance — a fast 5K runner without long runs will not hit the predicted marathon time.
What pace do I need for a sub-4-hour marathon?
About 5:41 per kilometre or 9:09 per mile. Most runners target slightly faster — around 9:00/mile — to build a buffer for slower miles, aid stations and the inevitable late fade. Set the marathon preset with a 3:59:00 goal to see the full split sheet.
What is a good running pace for a beginner?
Roughly 7:00–8:00 per kilometre (11:15–12:50 per mile) is typical when starting out. The better test is the talk test: if you cannot hold a conversation, you are running too fast. Early on, time on feet matters far more than pace.
Does this work for walking or cycling?
For walking, yes — the pace, time and distance maths is identical, and the split table works the same way. For cycling the conversion is fine but the training-pace logic does not transfer, since cyclists work from power output rather than pace.