Split Time Calculator

Even splits

Every kilometre or mile is run at the same pace. Your total time is divided evenly across every split unit.

Negative splits

You run the second half of the race faster than the first. Enter how many seconds faster you want the second half to be; the calculator distributes those seconds so each second-half split is proportionally quicker than the corresponding first-half split. Total time stays fixed.

Positive splits

The opposite: a faster first half, slower second. Common in races where runners go out too hard. Useful for planning a controlled fade.

Distance and units

• Common presets: 5 K, 10 K, Half Marathon (21.0975 km), Marathon (42.195 km).
• Choose a Custom distance and set it in kilometres or miles. All internal maths uses km; miles are converted automatically.
• The split unit (per km or per mile) is independent of the distance unit; e.g. you can plan a marathon in km splits measured per mile.

Half-marathon marker

A dashed line in the table marks the halfway point so you can see exactly where the second half begins.

All calculations run in your browser. No data is sent to a server.

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.