How to use this tool

Choose what to solve for. Select whether you want to find pace, total time, or distance.
Enter two known values. Provide the two values you already know (e.g., distance and time).
Click Calculate. The missing value is computed and split times for common race distances are displayed.

How to use the pace calculator

Running pace is expressed as minutes and seconds per kilometre (or per mile). This calculator is bidirectional: enter any two of distance, time, or pace and it will compute the third.

The calculator works in seconds: pace is total time divided by distance, finish time is distance multiplied by pace, and distance is time divided by pace. For example, 25 minutes over 5 kilometres is 1,500 ÷ 5 = 300 seconds per kilometre, or 5:00/km. The race table applies that same even pace to common distances; terrain, weather, stops, and course measurement can change an actual result.

Common race pace targets

5K in under 30 min: aim for 5:59/km (9:38/mi) or faster
5K in under 25 min: aim for 4:59/km (8:01/mi) or faster
10K in under 60 min: aim for 5:59/km (9:38/mi) or faster
Half marathon in under 2 hours: requires a 5:41/km (9:09/mi) pace
Marathon in under 4 hours: requires a 5:41/km (9:09/mi) pace
Marathon in 3:30: averages about 4:59/km (8:01/mi). For a finish under 3:30, target a little faster, such as 4:58/km (8:00/mi).

Pace vs speed

Pace (min/km or min/mi) and speed (km/h or mph) are reciprocals of each other. Runners typically talk in pace; cyclists usually talk in speed. A pace of 5:00/km equals a speed of 12 km/h (7.46 mph).

Training zones

Zone	% Max HR	Purpose	Approx. pace (5:00/km runner)
Zone 1 - Easy/Recovery	65–75%	Recovery, aerobic base	6:15–7:30/km
Zone 2 - Aerobic	75–85%	Endurance building	5:30–6:15/km
Zone 3 - Tempo/Threshold	85–90%	Lactate threshold	5:00–5:20/km
Zone 4 - VO₂ max intervals	90–95%	Aerobic capacity	4:15–4:45/km
Zone 5 - Speed	95–100%	Neuromuscular, speed	Under 4:00/km

Most training programs recommend spending 80% of weekly mileage in Zones 1–2 and 20% in Zones 3–5 (the "80/20 rule" or polarized training model).

Negative splits strategy

A negative split means running the second half of a race faster than the first. Most world records and personal bests are set with even or negative splits. The strategy works because:

Starting conservatively prevents early lactate accumulation that is hard to recover from.
Remaining glycogen stores allow a strong finish.
The psychological boost of passing other runners in the second half is real.

To plan a negative split: target your first half at 2–3% slower than goal race pace, and your second half at goal pace or slightly faster.

Heart rate vs. pace zones

Pace is affected by external factors: heat, humidity, hills, fatigue, and headwinds all slow you down without changing your actual effort level. Heart rate is a more consistent proxy for physiological effort.

Most coaches recommend using heart rate as the primary guide for easy and aerobic training (Zones 1–2), where the temptation to run too fast is greatest. For interval work (Zones 4–5), pace targets are more practical because heart rate lags behind effort at high intensities.