Pace vs. Perceived Effort
Pace numbers only tell part of the story. The same 5:30/km pace can feel easy on a flat road in cool weather and brutal on a hilly trail in summer heat. External factors that affect the effort-pace relationship include temperature (pace slows 1–3% per 5°C above 15°C), altitude (VO2max drops ~3% per 1,000m above sea level), wind (headwinds can cost 5–15 seconds per kilometre), terrain (trail running typically requires 10–20% more effort than road at the same pace), and elevation changes (uphill adds ~12–15 seconds per kilometre per 1% grade). Heart rate provides objective effort data but lags behind actual effort by 30–90 seconds — on short intervals or hills, your HR won't accurately reflect the work being done. Running power (measured by Stryd or estimated) responds instantly and captures terrain and wind effects. For daily training, the RPE (Rate of Perceived Exertion) scale from 1–10 remains one of the most reliable effort metrics: easy runs should feel 3–4, tempo runs 6–7, and intervals 8–9. Use this calculator to find your target pace, then adjust based on conditions.
How to Use the Pace Calculator
raacon/'s free pace calculator helps runners and cyclists convert between pace, speed, and finish time for any distance. All calculations run entirely in your browser — no data is sent to any server.
Pace to Finish Time
Enter your target pace (e.g. 5:30 min/km) and your race distance. The calculator will instantly show your projected finish time along with a full splits table so you can track your progress at every kilometer or mile marker.
Goal Time to Required Pace
Have a goal time in mind? Enter your target finish time and the race distance to find out exactly what pace per kilometer (or mile) you need to maintain throughout the race. Use the race distance presets — 5K, 10K, Half Marathon, Marathon — for quick entry.
Speed to Pace Conversion
Treadmills and cycling computers often display speed in km/h. Use this mode to convert a speed like 10.0 km/h to its equivalent pace of 6:00 min/km.
Common Race Paces
| Pace (min/km) | Speed (km/h) | 5K | 10K | Half Marathon | Marathon |
|---|---|---|---|---|---|
| 4:00 | 15.0 | 20:00 | 40:00 | 1:24:23 | 2:48:45 |
| 4:30 | 13.3 | 22:30 | 45:00 | 1:34:56 | 3:09:53 |
| 5:00 | 12.0 | 25:00 | 50:00 | 1:45:29 | 3:30:59 |
| 5:30 | 10.9 | 27:30 | 55:00 | 1:56:02 | 3:52:04 |
| 6:00 | 10.0 | 30:00 | 1:00:00 | 2:06:35 | 4:13:11 |
| 7:00 | 8.6 | 35:00 | 1:10:00 | 2:27:42 | 4:55:24 |