About this calculator
Use it to set a goal or to check whether a target time fits the pace you train at.
How to use it
- Choose the race distance.
- Enter your pace per km.
- Read the finish time and halfway split.
The formula
Finish time = pace × distance
- pace
- minutes and seconds per km
- distance
- race distance in km
Worked example
Half marathon at 5:30 per km
- Finish = 5:30 × 21.0975 = 1:56:02.
- Halfway split: 58:01.
What the result means
Start slightly slower than goal pace and speed up later; it usually gives a better time.
Assumptions
- Even pace throughout.
Limitations
- Hills, heat and crowding slow real races.
Frequently asked questions
What pace for a sub-2-hour half marathon?
About 5:41 per km.
What pace for a 4-hour marathon?
About 5:41 per km as well, since 4:00:00 ÷ 42.195 km ≈ 5:41.
How long is a half marathon?
21.0975 km.
Not medical advice. This calculator is a general screening tool and cannot diagnose any condition. Results are estimates. Please talk to a doctor or a qualified health professional about your health and before making changes to diet, exercise or treatment.
Last reviewed on 1 October 2026. Found a mistake? Tell us.