Marathon Split Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter details
Goal time
::
Result
Fill in the fields to see your result.
Estimate only — real results depend on terrain, weather, fatigue, conditions and individual fitness. Not medical or coaching advice.
How to use this calculator
- Enter your goal marathon time.
- Read your even-pace splits at 5 km, 10 km, half and 30 km.
How it works
Even pace = goal time ÷ 42.195 km; each split is that pace × the distance.
Worked example
Sub-4. 4:00:00 ≈ 5:41 /km, 28:27 at 5 km, 2:00:00 at halfway.
Tips
- Times are estimates only — not medical or coaching advice. Always train safely and follow event rules.
- Distances are editable: choose “Custom…” to enter your own course lengths.
Frequently asked questions
Should I run even splits?
Even or slightly negative splits are the most reliable way to hit a marathon goal.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.