Running pace in min/km and min/mile from any distance and time, with speeds, a 400 m lap split, and projected finish times from 5K to marathon.
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FORMULA USEDRunning Pace Calculator
What pace really is
Pace is time per unit of distance — minutes and seconds per kilometer or per mile — and it is the number runners think in because it reads directly off a watch. The arithmetic is plain division: total seconds ÷ total distance = seconds per unit, then re-expressed as minutes and seconds. A 25:00 5K is 1,500 seconds across 5 km: exactly 5:00 per kilometer.
Kilometers, miles, and speed
One mile is 1.609344 km, so a pace converts by multiplying or dividing by that factor: 5:00/km is 8:03/mile. Speed is the reciprocal view — distance per hour instead of time per distance — and 5:00/km equals 12.0 km/h or 7.46 mph. Track workouts add one more framing: 400 m, one stadium lap, is simply four tenths of your per-kilometer pace.
Using the race projections
The split table stretches your pace across 5K, 10K, 15K, 10 miles, the half, and the marathon. It answers two questions at once: what today’s effort implies for longer races, and what a goal race demands in training. Note that doubling distance rarely doubles comfortably — the marathon projection assumes you can hold a 5K pace for 42 km, which is exactly the assumption marathon training exists to build.
Worked example
You run a 5K in 25 minutes flat: 25 × 60 = 1,500 seconds.
1,500 s ÷ 5 km = 300 s/km = 5:00 /km.
Per mile: 300 × 1.609344 = 483 s = 8:03 /mile; speed 12.0 km/h.
The table projects a 1:45:29 half and a 3:30:59 marathon at that pace.
How to use it
Pick kilometers or miles; the distance field follows your choice.
Type the race or workout distance and your finish time in hours, minutes, seconds.
Read pace in both units, speed, and your 400 m lap time.
Scan the table for projected finish times at standard race distances.
Frequently asked questions
How do I calculate my running pace?
Convert your finish time to seconds, divide by the distance, and re-split the result into minutes and seconds. A 50:00 10K is 3,000 seconds over 10 km = 300 seconds, or 5:00 per kilometer. The calculator does the division and both unit systems at once.
How do I convert between minutes per mile and minutes per kilometer?
Multiply by 1.609344 going from per-kilometer to per-mile, and divide going back. 5:00/km is about 8:03/mile; 8:00/mile is about 4:58/km. A quick field rule: per-mile pace is roughly 60% larger than per-kilometer pace.
What is a realistic beginner pace for a 5K?
Most new runners land between 6:30 and 8:30 per kilometer, finishing a 5K in 20–45 minutes. Anything under 30 minutes is a solid first-season goal, and walk-run intervals are a completely legitimate way to get there.
How does running speed differ from running pace?
They are reciprocals: pace is time per distance (min/km) and speed is distance per time (km/h). 5:00/km is 12 km/h. Pace dominates training talk because intervals are prescribed as goal splits, while speed shows up on treadmills and in cycling comparisons.
Are the marathon and half-marathon projections realistic?
Only as estimates of what an even pace implies — the table assumes you can hold the short-race pace for the whole distance, which real fatigue curves say you cannot. Widely used race predictors add a fatigue allowance; treat the table’s marathon column as an ambitious upper bound unless your training includes long runs near that pace.
What is negative splitting and why is it recommended?
Running the second half faster than the first. Going out 5–10% slower than target pace preserves glycogen and keeps early effort aerobic, so the closing kilometers stay strong. It is the pacing strategy behind most personal bests at every distance from 5K up.