Pace Calculator
Distance, pace, time. Then what race day does to it.Enter any two of distance, pace and time. Get the third, then see what race-day heat, wind and hills do to it.
Pace Calculator
Splits
Running pace chart
Finish times at common paces. Distances are the official 5K, 10K, half marathon (21.0975 km) and marathon (42.195 km).
| Pace /mi | Pace /km | Marathon | Half marathon | 10K | 5K |
|---|---|---|---|---|---|
| 6:00 | 3:44 | 2:37:19 | 1:18:39 | 37:17 | 18:38 |
| 6:30 | 4:02 | 2:50:25 | 1:25:13 | 40:23 | 20:12 |
| 7:00 | 4:21 | 3:03:32 | 1:31:46 | 43:30 | 21:45 |
| 7:30 | 4:40 | 3:16:38 | 1:38:19 | 46:36 | 23:18 |
| 8:00 | 4:58 | 3:29:45 | 1:44:53 | 49:43 | 24:51 |
| 8:30 | 5:17 | 3:42:52 | 1:51:26 | 52:49 | 26:25 |
| 9:00 | 5:36 | 3:55:58 | 1:57:59 | 55:55 | 27:58 |
| 9:30 | 5:54 | 4:09:05 | 2:04:32 | 59:02 | 29:31 |
| 10:00 | 6:13 | 4:22:11 | 2:11:06 | 1:02:08 | 31:04 |
| 10:30 | 6:31 | 4:35:18 | 2:17:39 | 1:05:15 | 32:37 |
| 11:00 | 6:50 | 4:48:24 | 2:24:12 | 1:08:21 | 34:11 |
| 11:30 | 7:09 | 5:01:31 | 2:30:45 | 1:11:27 | 35:44 |
| 12:00 | 7:27 | 5:14:38 | 2:37:19 | 1:14:34 | 37:17 |
| 12:30 | 7:46 | 5:27:44 | 2:43:52 | 1:17:40 | 38:50 |
| 13:00 | 8:05 | 5:40:51 | 2:50:25 | 1:20:47 | 40:23 |
How the calculator works
Distance, pace and time are tied together: pace × distance = time. Type any two and the third is the result. The presets load the official race distances, and the BQ, Chicago, NYC and OTQ chips load a qualifying standard for your age group.
Time and pace fill in from the right like a stopwatch: typing 3, 3, 0, 0, 0 reads 3:30:00. Typing the colons yourself works too. One mile is 1.609344 km; switch between miles and kilometers at any point and the numbers convert.
Race-day conditions
Search a race to pull its forecast and, where the course is mapped, its hills mile by mile, wind along the route and altitude along the course, or a place for the weather there right now. Heat uses the WBGT model behind every racecast.io race page, wind uses aerodynamic drag, hills use the Minetti grade cost uphill and a gentler downhill curve checked against race results, and altitude adds about 1% per 1,000 ft above 2,000 ft. Each factor is shown in words (slower, faster, no effect) and multiplied into one combined effect. The time you type is read two ways: as a flat-day time, the race-day finish is what those conditions turn it into; as a goal for that race, True Effort is what it is worth on a flat, cool, calm day.
Read more in how weather changes marathon pace, the race pacing guide, and what a pace band is. Every race on racecast.io has this calculator built into its forecast page.
Pace calculator questions
- How do I calculate my running pace?
- Divide your time by your distance. A 3:30:00 marathon (26.2 miles) is 210 minutes ÷ 26.2 = 8.01 minutes per mile, or 8:00 /mi. Enter any two of distance, pace and time above and the third is filled in.
- What pace do I need to run a 4-hour marathon?
- 9:09 per mile (5:41 per kilometer). A 3:30 marathon needs 8:00 /mi, a 3:00 marathon needs 6:52 /mi, and a 2-hour half marathon needs 9:09 /mi.
- How much does heat slow a marathon?
- The calculator uses the same WBGT model as racecast.io race pages: no penalty below a wet bulb globe temperature of about 50°F, then roughly 0.26 to 0.35% per degree above it, depending on pace. A 72°F, 65% humidity day costs around 5 to 6% versus cool conditions, which is 10 minutes or more on a 3:30 marathon.
- Does the calculator account for hills and altitude?
- Yes. Course gain is priced with the Minetti energy-cost polynomial and loss with a gentler downhill curve checked against real race results, so climbing costs more than descending gives back. Altitude adds about 1% per 1,000 feet above 2,000 feet. Load a race with a mapped course and its hills (priced mile by mile along the route, as on the race page), wind along the route and altitude fill in automatically; altitude is averaged along the route rather than taken at the start line.
- What is the difference between race-day finish and True Effort?
- They read the same time two ways. If the time you enter is what you would run on a flat, cool, calm day, the race-day finish is what the course and forecast turn it into (your time multiplied by the combined effect). If the time is your goal for that race, True Effort is the flat-day time it equals (your time divided by the combined effect). On a warm, hilly day the race-day finish is slower than your time and True Effort is faster.
- How are the race predictions calculated?
- With Riegel's formula: T2 = T1 × (D2 ÷ D1)^1.06. It assumes you are trained for the longer distance, so a 5K time predicts a marathon only if you have the mileage behind it.
- What are the Boston qualifying times?
- For the 2027 Boston Marathon, 2:55:00 for men and 3:25:00 for women and non-binary athletes aged 18 to 34, easing by age group to 4:50:00 and 5:20:00 at 80 and older. Tap the BQ chip above to load any age group's standard, and remember the acceptance cut-off has run several minutes under the standard in recent years.