Running
19 calculators
Running calculators covering pace and speed, race prediction, training paces, field tests of aerobic fitness, and the adjustments that make a time on one course comparable to a time on another.
Pace is the base unit that most of the rest builds on: time divided by distance, converted between min/km and min/mile through the exact factor 1.609344.
- Marathon Time Predictor Estimate your marathon finish time from a recent half-marathon performance using Riegel's formula.
- Pace Converter (min/mile to min/km) Convert running pace between minutes per mile and minutes per kilometer instantly.
- Race Time Predictor (Riegel Formula) Estimate race finish time at a new distance using the Riegel formula and a known performance.
- Running Pace Calculator Calculate average running pace, speed, and split times from distance and duration.
- VDOT Calculator (Jack Daniels) Estimate running fitness (VDOT) from race performance using Jack Daniels's Running Formula equations.
- Age-Graded Running Performance Calculator Express any race result as a percentage of a reference standard using the WMA ratio formula.
- Beep Test (20 m Shuttle Run) Convert a beep test level into estimated VO2max using the Léger 20 m shuttle run equation.
- Cooper 12-Minute Run Test Convert a 12-minute run distance into an estimated VO2max using Cooper's 1968 field-test equation.
- Elevation-Adjusted Pace Calculator Estimate time cost of vertical gain using the 12 s/mile per 100 ft coaching heuristic.
- Heat Pace Adjustment Convert a base running pace into a heat-adjusted equivalent pace using a published rule-of-thumb slowdown per degree above 15 °C.
- Marathon Splits Calculator Convert a marathon goal time into per-kilometer pace and checkpoint splits for race-day pacing.
- Rockport 1-Mile Walk Test Estimate VO2max from a brisk one-mile walk using the Kline 1987 regression with weight, age, sex, time, and finishing heart rate.
- Running Cadence Calculator Calculate average steps per minute from total step count and run duration.
- Running Splits Calculator Break your run into equal splits and see the cumulative time at each distance marker.
- Training Pace Calculator (from VDOT) Calculate Easy, Marathon, Threshold, and Interval paces from your VDOT score using Daniels' formula.
- Treadmill Pace Converter Convert treadmill speed in mph to running pace in minutes per mile and minutes per kilometer.
- Negative Split Pace Calculator Split your race time into a slower first half and faster second half with adjustable pace gaps.
- Running Power Calculator Estimate running power in watts from body weight and pace using a Stryd-style metabolic coefficient.
- Stride Length Calculator Calculate stride length from distance and step count using biomechanical gait-cycle definitions.
Prediction, VDOT and training paces
Race prediction from a known time rests on Riegel's formula, which scales time with distance raised to the power 1.06. The exponent encodes the observation that pace slows as distance grows; at exactly 1.0 the formula would assume a runner holds the same pace indefinitely.
VDOT takes a different route, converting a race performance into an estimate of effective aerobic capacity and then reading training paces off that single figure. The value of the approach is internal consistency: easy, marathon, threshold, interval and repetition paces all derive from one number rather than from separate rules of thumb.
Both approaches assume appropriate training for the target distance. A runner with a fast 5 km and no long runs will not hit the marathon time Riegel projects, because the formula extrapolates from physiology the training has not built.
Field tests and course adjustments
The Cooper 12-minute test, the Rockport walk test and the multi-stage beep test all estimate aerobic capacity from a field protocol rather than a laboratory gas-exchange measurement. Each uses its own regression equation, and each carries the error of the equation plus the pacing accuracy of the person doing the test.
Elevation and heat adjustments answer a different question: what a time on one course is worth against another. Elevation-adjusted pace applies a cost per metre of vertical gain, and heat adjustment applies a slowdown that grows with temperature and humidity. Naismith's rule, elsewhere on the site, does the equivalent for walking terrain.
Cadence and stride length close the loop between the two ways of describing the same movement: speed is cadence multiplied by stride length, so any two of the three fix the third.
Common questions
How do you calculate running pace?
Divide total time by total distance in matching units, converting the time to decimal minutes first. A 10 km run in 52 minutes 30 seconds becomes 52.5 ÷ 10 = 5.25 minutes per kilometre, and the 0.25 converts back to 15 seconds, giving 5:15 min/km. Multiplying by 1.609344 gives 8:27 min/mile. The commonest error is reading a clock-format 5:15 as the decimal 5.15, which is ten seconds per kilometre away.
How accurate are marathon time predictors?
Riegel's formula extrapolates from one race time using a fixed exponent of 1.06, and it is generally closer over a short extrapolation than a long one. Predicting a half marathon from a 10 km tends to hold up better than predicting a marathon from a 5 km, where the gap between the physiology tested and the physiology required is largest. The prediction also assumes training appropriate to the target distance, which the formula has no way to see.
What is VDOT?
VDOT is a single number derived from a race performance that represents effective aerobic capacity, accounting for both oxygen uptake and running economy. Its practical use is that every training pace — easy, marathon, threshold, interval, repetition — is read off that one figure, so the paces stay consistent with each other. Updating it after a race updates the whole set at once.