🏃 Running Pace Calculator

Calculate pace, finish time, or distance — pick what you know.

PACE
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5K
10K
Half Marathon
Marathon

The Running Pace Calculator works out your pace, finish time or distance for any run. Training for a 5K, 10K, half marathon or marathon? Enter any two values and get the third instantly.

How to use the pace calculator

Three fields: distance, time, pace. Fill in any two and the third updates automatically. Pace can be entered as min/km or min/mile (toggle the unit). The race-prediction panel at the bottom takes your current pace and projects finish times for the four standard distances — 5K, 10K, half marathon, full marathon — using the Riegel formula, which accounts for the natural slow-down on longer events. Useful for setting a realistic target before race day or for checking that your training pace lines up with your goal time.

The math: pace, time and the Riegel projection

Pace is simply time ÷ distance; finish time is pace × distance. The interesting one is the race-distance projection. Peter Riegel's 1977 formula is T2 = T1 × (D2 / D1)1.06 — your time at distance 2 is your time at distance 1 scaled by the distance ratio raised to the 1.06 power. The 1.06 exponent encodes the "endurance penalty": doubling distance more than doubles time slightly, because pace inevitably drops as duration grows. The formula is widely used by coaches and is accurate to within a few percent for trained runners.

Frequently Asked Questions

What is a good running pace?
For beginners: 8–10 min/km (13–16 min/mile) is perfectly fine. Intermediate runners average 5–7 min/km. Elite runners race at under 3 min/km.
What pace do I need for a sub-30 minute 5K?
You need to run at 6:00 min/km (9:39 min/mile) or faster.
What pace do I need for a 2-hour half marathon?
You need to average 5:41 min/km (9:09 min/mile).
How can I improve my running pace?
Mix easy runs with interval training and one long run per week. Consistency matters more than intensity — most improvements come from running more often, not faster.
Why is the projected marathon pace slower than my 10K pace?
Endurance falls off with duration. The Riegel exponent reflects real-world race data — almost no one holds 10K pace for 42 km. Most runners slow by 60–90 seconds per kilometre between a 10K and a marathon.
Should I run at projected race pace in training?
Only on dedicated tempo days. Most weekly mileage should be 60–90 seconds slower than goal pace — easy effort. That's how endurance is built without injury.

Common race pace targets

Sub-30 5K → 6:00 min/km. Sub-50 10K → 5:00 min/km. Sub-2 half marathon → 5:41 min/km. Sub-4 marathon → 5:41 min/km sustained. Sub-3:30 marathon → 4:58 min/km. Each step down typically takes a season of consistent training to unlock; jumping multiple targets at once invites injury.

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