Pace is the number most runners train and race by: minutes and seconds for each mile or kilometer. This calculator solves for whichever of the three quantities you do not know — pace, finish time or distance — and fills in everything around it: speed, splits for every mile or kilometer, a 400-meter lap time and predictions for other race distances.
How to use the pace calculator
- Choose what to calculate: pace, finish time or distance.
- Select a standard race distance (1 mile to marathon) or choose Custom distance and enter it in miles, kilometers or meters.
- Enter the finish time as h:mm:ss or mm:ss, and/or the pace as mm:ss, depending on what you are solving for.
- Choose whether pace is per mile or per kilometer. Splits and predictions follow that choice.
Pace formulas
The three quantities are linked by one relationship:
Work in seconds to avoid errors with the 60-based clock, then convert back to minutes and seconds. Speed is the reciprocal of pace: mph = 60 ÷ (minutes per mile), and km/h = 60 ÷ (minutes per kilometer).
Worked example
You ran a 10K in 55:00 and want your pace:
55:00 = 3,300 seconds; 3,300 ÷ 10 km = 330 s = 5:30 per km
10 km = 6.2137 mi, so 3,300 ÷ 6.2137 ≈ 531 s = 8:51 per mile
Speed = 10 km ÷ 0.9167 h ≈ 10.91 km/h, or 6.78 mph.
Going the other way, a marathon (26.219 miles) at 9:00 per mile takes 26.219 × 540 s ≈ 14,158 s, or 3:55:58.
Finish times at common paces
| Pace per mile | Per km | 5K | 10K | Half marathon | Marathon |
|---|---|---|---|---|---|
| 7:00 | 4:21 | 21:45 | 43:30 | 1:31:46 | 3:03:32 |
| 8:00 | 4:58 | 24:51 | 49:43 | 1:44:53 | 3:29:45 |
| 9:00 | 5:36 | 27:58 | 55:55 | 1:57:59 | 3:55:58 |
| 10:00 | 6:13 | 31:04 | 1:02:08 | 2:11:06 | 4:22:11 |
| 11:00 | 6:50 | 34:11 | 1:08:21 | 2:24:12 | 4:48:24 |
| 12:00 | 7:27 | 37:17 | 1:14:34 | 2:37:19 | 5:14:38 |
Race distances are exact: 5,000 m, 10,000 m, 21,097.5 m for the half and 42,195 m for the marathon.
Predicting other race times
In 1981 engineer and marathoner Peter Riegel noticed that running performance falls off with distance in a consistent way, which he described with a simple power law:
The exponent 1.06 means doubling the distance slightly more than doubles the time. From a 55:00 10K, the formula predicts about 26:23 for a 5K, 2:01:21 for a half marathon and 4:13:01 for a marathon. The prediction assumes you are as well trained for the longer race as for the shorter one, so first-time marathoners usually finish slower than it suggests.
Using splits on race day
The splits table assumes perfectly even pacing, which is the most energy-efficient way to cover a flat course. Many experienced runners aim for even or slightly negative splits, running the second half a little faster than the first. Hills, heat, wind and crowded starts all shift real splits, so treat the table as a reference rather than a script. GPS watches also tend to measure a race as slightly long because runners rarely follow the shortest line, which can make your watch pace look a few seconds faster than your official pace.
For effort-based training, pair your paces with heart rate zones from the target heart rate calculator, and convert speeds with the mph to km/h converter.
This calculator is informational only and is not medical advice. If you are new to running, returning from injury or managing a health condition, consult a healthcare professional before increasing your training.
Frequently asked questions
How do I convert pace per mile to pace per kilometer?
Divide the pace per mile by 1.609344, because a mile is 1.609344 km. An 8:00 mile pace is 480 seconds ÷ 1.609344 ≈ 298 seconds, or 4:58 per kilometer. To go the other way, multiply by 1.609344.
What is the difference between pace and speed?
Pace is time per unit of distance (minutes per mile), and speed is distance per unit of time (miles per hour). They are reciprocals: divide 60 by your pace in minutes per mile to get mph, so a 10:00 pace is 6 mph.
How accurate are the race-time predictions?
The Riegel formula is a good rough guide for distances from about a mile to a half marathon when you are equally trained for each. Marathon predictions from short races are often optimistic, because endurance and fueling matter more over 26.2 miles.
How many laps of a track is a mile?
A standard outdoor track is 400 meters in lane 1, so a mile (1,609.344 m) is just over 4 laps — about 4.02. The result shows your time per 400 m lap to help with track sessions.