How do you convert between min/km and min/mi?

One mile equals 1.609344 km, so seconds per mile = seconds per km × 1.609344. A 5:00/km pace works out to about 8:03/mi.

Does the split table assume even pacing?

Yes. Real races usually fade slightly in the back half. Many runners aim for a "negative split" — a slightly faster second half — by holding 1–3% under target pace early on.

What pace do I need for a sub-4-hour marathon?

Roughly 5:41/km or 9:09/mi. Type 42.195 km and 4:00:00 into the calculator to confirm.

Why is pace better than speed for runners?

Pace expresses time per fixed distance, which is the way runners think during a race ("if I hold 5:00 km, what is my finish?"). Cyclists usually prefer speed (km/h) because their distance-per-time is much larger.

Does this account for elevation or wind?

No. For each 1% grade up, expect roughly 6 seconds per km slower; downhill saves about half that. Strong headwinds can cost 5–15 seconds per km depending on body size.

Running Pace Calculator

Solve for pace, time, or distance with km/mi unit toggle and a split table for any race goal.

Written by Golam Rabbani, Founder & Lead Engineer

This interactive tool requires JavaScript. Read the formula and worked example below; you can compute the result by hand.

How to use this running pace calculator

Pick which side of the triangle to solve for: pace, total time, or distance.
Enter the two known values — switch km/mi and /km vs /mi as needed (the calculator converts already-typed values).
Click Calculate to see the third value plus pace per km and per mile.
Review the even-pace split table to plan how each kilometre or mile should feel.
Copy the result for your race plan or Reset to try a different goal.

About this running pace calculator

The Running Pace Calculator solves the pace ↔ time ↔ distance triangle using the standard relation pace × distance = time. Pace is expressed in seconds per kilometre or per mile (1 mi = 1.609344 km, so sec/mi = sec/km × 1.609344). The split table multiplies your computed pace by 1, 2, 3 … units to show cumulative time at each marker — the same view as a race-day pace band. As a worked example, finishing a 10 km race in 50:00 gives a pace of 50·60 ÷ 10 = 300 seconds per km, or 5:00/km (≈ 8:03/mi); the 5 km split lands at 25:00 and the 8 km split at 40:00. The same engine answers "How fast must I run a half marathon to break 2:00?" by solving 7,200 s ÷ 21.0975 km = 341 s/km ≈ 5:41/km. Pace tools cannot account for hills, wind, heat, or fade in the back half — treat the split table as a target, not a guarantee. This tool is for general fitness education and is not medical advice — consult a qualified healthcare professional before training for endurance events, especially with heart, joint, or respiratory conditions.

FAQ

How do you convert between min/km and min/mi?: One mile equals 1.609344 km, so seconds per mile = seconds per km × 1.609344. A 5:00/km pace works out to about 8:03/mi.
Does the split table assume even pacing?: Yes. Real races usually fade slightly in the back half. Many runners aim for a "negative split" — a slightly faster second half — by holding 1–3% under target pace early on.
What pace do I need for a sub-4-hour marathon?: Roughly 5:41/km or 9:09/mi. Type 42.195 km and 4:00:00 into the calculator to confirm.
Why is pace better than speed for runners?: Pace expresses time per fixed distance, which is the way runners think during a race ("if I hold 5:00 km, what is my finish?"). Cyclists usually prefer speed (km/h) because their distance-per-time is much larger.
Does this account for elevation or wind?: No. For each 1% grade up, expect roughly 6 seconds per km slower; downhill saves about half that. Strong headwinds can cost 5–15 seconds per km depending on body size.