The Pace Calculator converts any two of distance, time and pace into the third, then shows unit splits, average speed and predicted finish times at common race distances. Enter a 5K, a training loop or a marathon plan in kilometres or miles, and the tool returns minutes per unit, cumulative splits and Riegel-style equivalent times labelled as predictions.
Pace is sports arithmetic, not a fitness diagnosis. A 5:00 per kilometre pace describes how fast a distance was covered; it does not say whether that effort was hard or easy for the runner who produced it. This page returns the numbers and shows the working so race plans stay grounded in measurable inputs rather than guesswork.
Calculate your running pace
Running pace is time divided by distance, usually stated as minutes and seconds per kilometre or per mile. With a known distance and a known finish time, the Pace Calculator divides the seconds by the distance in the chosen unit and formats the result as mm:ss per unit.
That single figure is the average pace for the whole effort, not a guarantee that every kilometre felt the same.
Enter distance in kilometres or miles, then hours, minutes and seconds for the effort. The tool solves for pace when those two are present, for finish time when pace and distance are present, and for distance when pace and time are present. Units stay consistent: a pace quoted per kilometre is not interchangeable with a pace per mile without conversion.
The result is an estimate of average pace under the inputs you give. Hills, wind, heat and fatigue change what a runner can hold from one day to the next, even when the maths on the page stay the same.
Find your finish time from a pace
Finish time is pace multiplied by distance. When a goal pace and a race distance are set, the Pace Calculator multiplies seconds per unit by the distance in that unit and returns a total time. That prediction assumes the goal pace is held evenly for the whole distance, which is a planning model rather than a promise of race-day conditions.
Common presets sit in the shared pace reference: 5K at 5,000 m, 10K at 10,000 m, half marathon at 21,097.5 m, marathon at 42,195 m, and the statute mile at 1,609.344 m. Choosing a preset fills the distance field so the finish-time solve uses a standard race length instead of a freehand course.
A finish time from a target pace is useful for pacing charts and watch alarms. It is still only as realistic as the pace chosen; a pace taken from a short, fresh interval session often does not hold for a full marathon.
Find the distance you can cover
Distance is time divided by pace when both are known. If a runner has a fixed window (for example forty minutes) and a sustainable pace, the Pace Calculator returns how far that combination covers in the selected unit.
The same arithmetic works in reverse of the pace solve: seconds of available time divided by seconds per unit yields units of distance.
This mode helps with lunch-run planning and time-capped workouts more than with race prediction. Course hills and stops for lights are not in the equation, so the returned distance is the flat, continuous equivalent of the inputs.
Treat the figure as a planning length. Real routes often run a little long or short of the GPS reading, and that measurement noise sits outside what the formula can correct.
Calculate pace for a 25-minute 5K
Take a runner who covers 5 km in 25 minutes even. That pair is the worked fixture for this page, and every step below uses those inputs only. 1. Convert time to seconds. 25 minutes = 25 × 60 = 1,500 seconds
2. Divide by distance in kilometres. 1,500 ÷ 5 = 300 seconds per kilometre
3. Format as mm:ss. 300 seconds = 5:00 per km
So a 5 km effort in 25:00 averages 5:00/km. Speed in the same run is distance over time: 5 km in 25 minutes is 12 km/h. Per-kilometre splits at even pacing land at 5:00, 10:00, 15:00, 20:00 and 25:00 cumulative.
The same effort in mile units needs a unit change first. Five kilometres is about 3.107 miles; 1,500 seconds divided by that distance yields a slower-looking per-mile pace for the identical run, because a mile is longer than a kilometre. The calculator handles that conversion when the distance unit is set to miles.
What this does not tell you: whether 5:00/km was easy or maximal for that runner, how the effort compared with heart-rate zones, or whether the course was flat. It tells you the average pace implied by those two numbers.
Read your split times
A split table breaks the total time into equal distance units and shows cumulative clock times at each mark. For the 25-minute 5K at even pacing, each kilometre costs 5:00, so the cumulative marks are 5:00, 10:00, 15:00, 20:00 and 25:00.
Mile splits follow the same idea when the pace unit is miles: total seconds divided by distance in miles, then stepped at each mile.
Even pacing is a modelling choice. Many races are run with a faster second half (a negative split) or a cautious first kilometre. The Pace Calculator's default split table assumes constant pace so the arithmetic stays transparent. Adjusting mid-race from feel or from a heart-rate target is a separate decision; the Target Heart Rate Calculator owns that framing.
Use splits as checkpoints, not as a verdict on a bad kilometre. A single slow split on a hill does not rewrite the average pace for the whole race unless the remaining distance is forced to compensate.
Predict times across race distances
Equivalent finish times at other race distances use the Riegel relation built into the engine:
T2 = T1 × (D2 / D1)^1.06T1 and D1 are the known time and distance; T2 is the predicted time at distance D2. The 1.06 exponent stretches time slightly more than a pure pace × distance scale, which is a common population model for how finish times slow as distance grows. Predictions are labelled as Riegel predictions and carry real individual scatter; they are not guarantees.
From the 5 km in 25:00 fixture, the engine's labelled predictions at the shared race distances include about 52:07 for 10K, about 1:55:00 for the half marathon, about 3:59:47 for the marathon, and about 7:31 for the mile. Those figures assume the same runner, similar conditions and no change in fitness between events. A specialist 5K runner and a marathoner with the same 5K time will often diverge at the longer distances.
Pure pace × distance (without the Riegel exponent) would understate how much longer distances usually cost. The page shows the Riegel form so the prediction method is visible rather than hidden.
Plan race-day pacing
Race-day pacing starts from a goal finish time or a goal pace, then turns that into per-unit targets and optional negative-split offsets. For a 5K, holding near the goal pace from the first kilometre is often enough.
For a half or marathon, many plans start a few seconds per unit slower than goal and move toward goal pace in the second half, which is a coaching preference rather than a rule the calculator enforces.
Presets for 5K, 10K, half marathon and marathon keep the distance field on standard lengths so finish-time solves match the distances people actually race. Mile pace remains available for track work and for runners who think in miles.
Pair pace targets with effort awareness. Heat, hills and crowding change sustainable pace; a watch alert at 5:00/km does not override safety. Anyone returning from injury or new to racing is better served by building from recent training times than from an ambitious Riegel projection alone.
Frequently asked questions
How do you calculate running pace?
Running pace is time divided by distance. Convert the finish time to seconds, divide by the distance in kilometres or miles, then format the result as minutes and seconds per unit. A 5 km run in 25:00 is 1,500 ÷ 5 = 300 seconds per kilometre, or 5:00/km.
What is a good pace for a 5K?
There is no single good pace. A 5:00/km average (25:00 for 5 km) is one concrete example on this page; other runners finish faster or slower depending on training, course and conditions. Compare against recent race or time-trial results rather than against a universal target.
How do I convert minutes per kilometre to minutes per mile?
Multiply the per-kilometre pace in seconds by 1.609344 (the number of kilometres in a statute mile), or enter the same run with the distance unit set to miles and let the Pace Calculator recompute. Do not treat a 5:00/km figure as a 5:00/mile figure; they describe different lengths.
What is the Riegel formula?
The Riegel prediction used here is T2 = T1 × (D2 / D1)^1.06, where T1 and D1 are a known race time and distance and T2 is the predicted time at distance D2. It is a population model with individual scatter, shown as a labelled prediction rather than a promise.
Can the calculator solve for distance?
Yes. Provide pace and available time; distance is time divided by pace in matching units. That mode suits time-capped runs more than race forecasting.
Do splits assume even pacing?
Yes. The default split table divides total time evenly across distance units. Real races often include surges, hills and negative splits; adjust from the even model when the course or plan calls for it.
Does pace measure fitness?
Pace measures how quickly a distance was covered under the conditions of that run. Fitness, heart-rate cost and perceived effort are separate. Two runners at the same pace can be at very different percentages of maximum effort.
Should beginners use race predictions?
Use them as rough planning aids. Build goal paces from recent training and shorter races, and treat long-distance Riegel projections as optimistic sketches until longer efforts confirm them. Medical clearance before intense training still belongs with a clinician when health history warrants it.
Summary
The Pace Calculator solves pace, time or distance from any two inputs, then shows speed, even-paced splits and Riegel equivalent times at standard race distances. A 5 km run in 25:00 averages 5:00 per kilometre, with cumulative kilometre marks every five minutes under even pacing.
Race presets use 5,000 m, 10,000 m, 21,097.5 m, 42,195 m and 1,609.344 m from the shared pace reference. Predictions stretch with the 1.06 Riegel exponent and remain estimates. Pace is average speed arithmetic for planning, not a verdict on fitness or health.