What pace should I run? Find out in 5 seconds
Pace is how many minutes you need to cover one kilometer (or one mile). The lower the number, the faster you're going. It's the basic unit every runner sets on their watch.
The calculator does three things based on the two values you already know: - time and distance → calculates pace (e.g. *I ran 10 km in 50:00, that's 5:00/km*), - pace and distance → calculates time (e.g. *if I hold 5:30/km on a half-marathon, I'll finish in 1:56:01*), - pace and time → calculates distance (e.g. *I ran for 30 minutes at 5:00/km, that's 6 km*).
Plus: race-time predictions for other distances (the established Riegel formula), kilometer and mile splits (the time you need to hit on each marker), and a negative-split suggestion: running the second half faster than the first, a classic racing trick.
How to use it
- Pick what to calculate: pace, time, or distance (the calculator solves the third value from the other two).
- Enter time as hours / minutes / seconds. Minutes and seconds stay in the 0-59 range, no "1:75:00" allowed.
- Enter distance: value plus unit (kilometers, miles, meters, or yards).
- Enter pace as "minutes:seconds", and choose per kilometer or per mile.
- Quick-fill buttons for 5K / 10K / half-marathon / marathon populate the distance with one click.
- Below the result you see all conversions: pace per km AND per mile, speed in km/h AND mph, plus a plain-language time breakdown (e.g. "1 hour 56 minutes 1 second").
- Then race-time predictions for 5K, 10K, half-marathon, marathon, and ultras, using the Riegel formula (well-established in running science).
- Splits (the time of each kilometer and each mile), show what to hold on each marker to hit your target.
When this is useful
Six typical situations where runners reach for a pace calculator:
- Planning your first 5K: you want to know the finish time at a comfortable 6:30/km. Enter pace + distance → 32:30. You know how much time to block on the course.
- Training for a half-marathon (21.1 km): your goal is sub-2 hours. Enter time 1:59:00 + distance 21.1 km → you need 5:38/km. The splits table tells you what your watch should show after each kilometer.
- Checking if a sub-4-hour marathon is realistic: you ran 10K in 48 minutes. Enter your 10K result and the calculator predicts your marathon finish (Riegel formula). If it says 3:50, you have headroom. If 4:15, work on endurance.
- Planning intervals: your coach says: "10 × 400 m at 4:00/km pace". What's that in seconds per 400 m? → 1:36 per interval. Set your watch and go.
- Comparing results across distances: you ran 5K in 23:00 and a half-marathon in 1:48:00. The half might predict a 22:30 5K, meaning the half was the better effort.
- Treadmill pace: treadmills show speed in km/h or mph, not pace. Set 12 km/h, what's that per kilometer? Pace 5:00/km → 12 km/h. Works both ways, instantly.