Free tool
Calculate your race pace, splits, and finish time.
Convert running pace, distance, and time three ways. Plug in any two of the three and get the missing value plus full per-kilometre and per-mile split tables for 5K, 10K, half marathon, and marathon. Supports min/km, min/mi, and mph for cyclists. Free, no signup, runs in your browser.
Free · no signup · your file stays on your device
Edit any two fields. The third updates automatically.
hours
minutes
seconds
Minutes and seconds per kilometer
Race splits
5K
25:00| Split | Cumulative |
|---|---|
| 1 km | 5:00 |
| 2 km | 10:00 |
| 3 km | 15:00 |
| 4 km | 20:00 |
| 5 km | 25:00 |
10K
50:00| Split | Cumulative |
|---|---|
| 1 km | 5:00 |
| 2 km | 10:00 |
| 3 km | 15:00 |
| 4 km | 20:00 |
| 5 km | 25:00 |
| 6 km | 30:00 |
| 7 km | 35:00 |
| 8 km | 40:00 |
| 9 km | 45:00 |
| 10 km | 50:00 |
Half Marathon
1:45:29| Split | Cumulative |
|---|---|
| 1 km | 5:00 |
| 2 km | 10:00 |
| 3 km | 15:00 |
| 4 km | 20:00 |
| 5 km | 25:00 |
| 6 km | 30:00 |
| 7 km | 35:00 |
| 8 km | 40:00 |
| 9 km | 45:00 |
| 10 km | 50:00 |
| 11 km | 55:00 |
| 12 km | 1:00:00 |
| 13 km | 1:05:00 |
| 14 km | 1:10:00 |
| 15 km | 1:15:00 |
| 16 km | 1:20:00 |
| 17 km | 1:25:00 |
| 18 km | 1:30:00 |
| 19 km | 1:35:00 |
| 20 km | 1:40:00 |
| 21 km | 1:45:00 |
| 21.10 km | 1:45:29 |
Marathon
3:30:59| Split | Cumulative |
|---|---|
| 1 km | 5:00 |
| 2 km | 10:00 |
| 3 km | 15:00 |
| 4 km | 20:00 |
| 5 km | 25:00 |
| 6 km | 30:00 |
| 7 km | 35:00 |
| 8 km | 40:00 |
| 9 km | 45:00 |
| 10 km | 50:00 |
| 11 km | 55:00 |
| 12 km | 1:00:00 |
| 13 km | 1:05:00 |
| 14 km | 1:10:00 |
| 15 km | 1:15:00 |
| 16 km | 1:20:00 |
| 17 km | 1:25:00 |
| 18 km | 1:30:00 |
| 19 km | 1:35:00 |
| 20 km | 1:40:00 |
| 21 km | 1:45:00 |
| 22 km | 1:50:00 |
| 23 km | 1:55:00 |
| 24 km | 2:00:00 |
| 25 km | 2:05:00 |
| 26 km | 2:10:00 |
| 27 km | 2:15:00 |
| 28 km | 2:20:00 |
| 29 km | 2:25:00 |
| 30 km | 2:30:00 |
| 31 km | 2:35:00 |
| 32 km | 2:40:00 |
| 33 km | 2:45:00 |
| 34 km | 2:50:00 |
| 35 km | 2:55:00 |
| 36 km | 3:00:00 |
| 37 km | 3:05:00 |
| 38 km | 3:10:00 |
| 39 km | 3:15:00 |
| 40 km | 3:20:00 |
| 41 km | 3:25:00 |
| 42 km | 3:30:00 |
| 42.20 km | 3:30:59 |
How it works
- 1
Pick the two variables you know
Distance and time, distance and pace, or time and pace - any two. The third is fully determined.
- 2
Type the numbers in any unit
Kilometers, miles, or meters for distance. Minutes-per-km or minutes-per-mile for pace. The third value updates as you type.
- 3
Read your split table
Once a pace is set, we project even-split tables for 5K, 10K, half-marathon, and marathon - switchable between km and miles.
- 4
Take the plan onto the road
Save the splits to your watch face or to Domestique as a planned workout, then chase them on race day.
The math
Pace is a unit conversion problem. There are three quantities - distance D, time T, and pace P - bound by a single equation:
If pace is in minutes per kilometer and distance is in kilometers, you multiply pace × distance to get time. If you want pace in minutes per mile from a kilometer-based pace, multiply by 1.609344 (the number of kilometers in a mile).
Worked example: 10K in 50 minutes
Distance = 10 km. Time = 50 minutes = 3000 seconds. Pace = 3000 ÷ 10 = 300 seconds per km = 5:00/km. Convert to miles: 5:00/km × 1.609 = 8:02.7/mi. So a 50-minute 10K means averaging 5:00 per km or 8:03 per mile - every kilometer, every mile, no exceptions.
Worked example: half-marathon target time
You want to run a 1:45:00 half-marathon. Distance = 21.0975 km. Time = 6300 seconds. Pace = 6300 ÷ 21.0975 = 298.6 seconds per km = 4:58.6/km. To break 1:45, every km has to clear 4:59. The calculator handles the fractional seconds for you.
Why split tables drift slightly
A "5K" is exactly 5000 meters. A "half marathon" is 21,097.5 meters - half of 42,195. The marathon is 26.2188 miles, not 26.2. Calculators that round to 21.1 km or 26.2 miles will drift 5-10 seconds across a marathon. We use the exact figures.
How to use this in training
Knowing your goal pace is the easy part. Building the ability to hold it is the work. A few practical patterns:
- Lock paces into key workouts. If your half-marathon goal pace is 4:58/km, you should be doing tempo runs at 5:05-5:10/km and intervals at 4:40-4:50/km. The calculator gives you the anchor; the surrounding paces follow from physiology.
- Run race-pace miles inside long runs. A common workout is a 20-22km long run with 8-12km in the middle at goal half-marathon pace. The calculator tells you what the splits should be - you just have to hit them.
- Calibrate on flat, neutral conditions. Calculator pace is constant-effort pace on flat ground in good weather. Mark a flat, traffic-free loop and use it for repeated time trials so the number you plug in is honest.
- Use it for pacing the early miles. The single biggest cause of blown races is starting too fast. Pre-print the first three splits, glance at your watch at the markers, and dial back immediately if you're ahead.
- Keep an honest gap between training pace and race pace. Easy runs should be at least 60-90 seconds per km slower than race pace. If you can't make yourself slow down, you're not recovered enough to race.
Common mistakes & misconceptions
Confusing pace with speed
Pace is time per distance (lower is faster). Speed is distance per time (higher is faster). Cyclists and treadmills use speed; runners use pace. Don't mix them in the same workout description.
Assuming a 5K pace will hold for a marathon
Pace slows as distance grows. A 22-minute 5K runner does not run a 3:05 marathon. Use the Race Time Predictor for cross-distance projections - the Riegel formula models the slowdown explicitly.
Using GPS pace as gospel during a race
GPS pace updates with 5-10 seconds of lag and is noisy under trees, in cities, or at the start of a race. Trust the lap pace and the mile markers, not the instantaneous reading.
Front-loading the race
Starting 5-10 seconds per km faster than goal pace feels easy in mile one and disastrous in mile twenty. The negative-split runner almost always finishes ahead of the even-split runner who finishes ahead of the positive-split runner.
Ignoring elevation in the split chart
A constant-pace chart assumes flat ground. On hilly courses, you'll need to plan for slower uphill splits and faster downhills. Effort is the variable that should stay constant, not pace.
Related tools
More from running tools
See all toolsRace Time Predictor
Riegel projections across all race distances.
OpenVO2 Max Estimator
Race, Cooper, or Rockport - your aerobic ceiling.
OpenMarathon Pace Charts
Even-split tables for any race distance.
OpenGrade-Adjusted Pace Calculator
What your pace would be on flat ground.
OpenExplore the FIT toolkit
14 free tools to view, edit, fix, and convert your Garmin FIT files.
Open the toolkitFAQ
How is running pace calculated?
Pace equals total elapsed time divided by total distance. We compute internally in seconds per meter, then convert to minutes per kilometer or minutes per mile so you see the units you actually train in.
What is a good 5K pace for a recreational runner?
A typical recreational pace is around 6:00-7:00 per kilometer (roughly 9:30-11:15 per mile). Sub-25 minute 5K times put most runners in a moderately trained range; sub-20 means real fitness; sub-18 is competitive amateur territory.
Should I race in even splits or negative splits?
Negative splits - running the second half faster than the first - produce the best race outcomes for nearly every athlete in distances from 5K to marathon. Even pacing is the next-best option. Positive splits (going out hot) wreck most goal races.
Why do my actual race times not match the calculator?
The calculator gives you the math of constant pace. Real races involve elevation, wind, terrain, fueling, and pacing discipline. The chart is a target, not a forecast.
How do I convert min/km to min/mile?
Multiply your min/km value by 1.609. So 5:00/km = 8:03/mile. The calculator does this automatically when you change the pace unit.
Can I use this for cycling or swimming?
It works for any constant-pace activity. Cyclists usually think in km/h or mph rather than minutes per unit, and swim pace is typically given per 100m - but the underlying math is identical.
Why is my GPS pace different from my treadmill pace?
Treadmills measure belt speed; GPS measures ground distance covered with some error. A 1-3% discrepancy is normal. Use one as the source of truth for a given block of training and don't mix them.
What pace should I run for an "easy" run?
Easy pace is typically 60-90 seconds per kilometer slower than goal race pace (about 1:30-2:30 per mile slower), and should feel conversational. If you can't hold a sentence, you're running too hard.
How accurate is this calculator at predicting marathon time from 5K time?
For race-time prediction across distances, use the Riegel formula in the Race Time Predictor - that accounts for the fact that pace slows as distance grows. The pace calculator here assumes constant pace, which is fine for splits but not for projecting longer-distance times.
Save your training to a real log
Calculators are useful. A complete training log that tracks pace, fitness, and race goals over years is the actual product.
Join the waitlist