Ideal Race Pace Calculator
Enter your goal finish time for a 5K, 10K, half or full marathon and get the exact pace per kilometre and per mile you need to hold, plus your average speed.
How it works
pace per km = goal time (s) ÷ distance (km) · speed = distance ÷ time
Race pacing is deceptively simple: divide your goal finish time by the race distance to get the average pace you must sustain for every kilometre or mile. The hard part is holding it evenly. Runners who start faster than goal pace to "bank time" almost always slow more in the back half than they gained up front, so the even-pace figure is the one to lock into. Seeing the equivalent speed helps you dial it in on a treadmill or bike computer.
Worked example
A 1:45:00 half marathon is 6,300 seconds over 21.0975 km, so pace = 6,300 ÷ 21.0975 = 298.6 s/km ≈ 4:59 per km (about 8:01 per mile) at a speed of 12.06 km/h.
Frequently asked questions
Should I run even pace or start fast?
Even pacing, or a slightly faster second half (a negative split), gives most runners their best times. Going out faster than goal pace spends glycogen early and usually costs more time later than it saved.
Why do the per-km and per-mile paces look so different?
A mile is 1.609 km, so the per-mile pace is always the larger number — it is the time to cover more ground. Both describe the same speed; use whichever your watch or race markers show.
Does this account for hills or wind?
No — it gives the flat, even average you need. On hilly courses you would run harder uphill and ease downhill to keep effort steady, aiming to hit the same overall average.
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Educational estimate, not medical advice — for personal health decisions consult a qualified healthcare professional.