Half Marathon Pace Calculator

Calculate half marathon pace, speed, and 5K splits from a finish time or target pace.

Last updated: 9/28/2026

The half marathon is 21.0975 kilometers, half of 42.195 km, which is 13.109 miles. It is long enough that 5K pace will not hold, and short enough that marathon fade is the wrong comparison.

Calculator Inputs

Calculate*

Finish time (hours)

Used when calculating pace from a finish time.

Finish time (minutes)

Finish time (seconds)

Pace minutes

Used when calculating a finish time from pace.

Pace seconds

Pace unit*

Results

Enter values above to see your results

How to use this calculator

The default is 1:50:00. Change the hours and minutes to your goal, or switch the mode and type a pace you have held in training.
Pick minutes per kilometer or minutes per mile before you read the finish time. A 6:00 pace is a very different workout in the two units.
Use the 5K, 10K, 15K, and 20K rows as checkpoints. The finish row covers the last 1.0975 km.

How the calculation works

Finish time in seconds ÷ 21.0975 = seconds per kilometer. The same finish time ÷ 13.109 miles = seconds per mile.

For a 1:50:00 half marathon, 6,600 seconds ÷ 21.0975 = 313 seconds, or 5:13/km. In miles that is 8:23/mile. Speed is 3,600 ÷ 313 ≈ 11.5 km/h.

Because the course is exactly half a marathon, a pace that finishes a half in 2:00:00 finishes a full marathon in 4:00:00 only if you hold it for twice the distance. Most runners cannot. Treat a half-marathon result as a fitness marker, then use the race time predictor instead of doubling the clock.

Where a half marathon sits between a 10K and a marathon

A 1:45:00 half is 4:59/km (8:01/mile). A 2:00:00 half is 5:41/km (9:09/mile), the same average pace as a 4:00 marathon, packed into half the distance. A 2:15:00 half is 6:24/km (10:18/mile).

Negative splits are more realistic here than in a first marathon because the pace is closer to threshold for a shorter time. The table still assumes even effort so you have a number to compare against each 5K marker.

Worked example

1:50:00 half marathon

Time in seconds:1 × 3,600 + 50 × 60= 6,600 s

Pace per km:6,600 ÷ 21.0975= 5:13 /km

Pace per mile:6,600 ÷ 13.109= 8:23 /mile

10K checkpoint:6,600 × (10 ÷ 21.0975)= 52:08

Half marathon pace chart

Even pace over 21.0975 km (13.109 miles).

Finish	min/km	min/mile	Speed
1:24:23	4:00	6:26	15.0 km/h
1:34:56	4:30	7:15	13.3 km/h
1:45:29	5:00	8:03	12.0 km/h
1:56:02	5:30	8:51	10.9 km/h
2:06:35	6:00	9:39	10.0 km/h
2:17:08	6:30	10:28	9.2 km/h
2:27:41	7:00	11:16	8.6 km/h

Frequently Asked Questions

How long is a half marathon?

21.0975 kilometers, or 13.109 miles. A course labeled 13.1 miles is the same race rounded for signs.

What is a 2 hour half marathon pace?

5:41 per kilometer or 9:09 per mile. You reach 10K in 56:53 and 15K in 1:25:19 if the pace stays even.

Can I double a half marathon time to predict a marathon?

Doubling ignores fatigue. A runner who holds 5:30/km for a half often slows over a full marathon. Project the longer race with the race time predictor, which applies a distance adjustment, and still treat it as a projection.

Related guides

Guides & Articles

Running

Average Half Marathon Times by Age

A half marathon is 21.0975 km. Wide planning ranges by age, the pace at each end, and why a published average is a weak target.

Read guide →

Running

Average Marathon Times by Age

Marathon planning ranges by age, with the pace at each end. These are coaching bands, not race medians. A 4:00 marathon is 5:41 per kilometer at every age.

Read guide →

Running

Average Running Pace by Age and Distance

Age does not change the pace math. Wide recreational planning ranges for 5K, 10K, half marathon, and marathon, plus the pace each clock time requires.

Read guide →