Marathon Pace Calculator
Turn a marathon target into a pace per kilometre and per mile, and the time to be on at each split.
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The formula
pace = target time ÷ 42.195 km
The splits assume an even pace from start to finish. Each one is the elapsed time to be on when you pass that point.
What to watch out for
Pacing. Start no faster than target pace. The first 10 km should feel easy, and a minute banked early can cost several after 30 km. Reaching halfway on target or a little behind it is a good sign. If you need to walk the aid stations, build that time into the plan.
Fuelling. Aim for 30–60 g of carbohydrate an hour, starting within the first 30 to 45 minutes, and drink to thirst. Some runners can absorb up to about 90 g an hour, but only with practice. Try the exact gels and drinks on long runs. In the two days before, eat more carbohydrate than usual: about 10 g per kg of body weight a day is the usual target for loading.
Conditions. Allow for heat and hills by slowing your target from the start, not after they have hurt you.
Frequently Asked Questions
What pace do I need for a 4-hour marathon?
5:41 per km, or 9:09 per mile.
What is the halfway split for a 4-hour marathon?
2:00:00 at an even pace. Many well-paced runners reach it a minute or two slower than that if they plan to finish strongly.
Why does my watch show more than 42.2 km?
Courses are measured along the shortest line, and nobody runs exactly that. If you cover 1% more, you need 5:38 per km on your watch to finish a 4-hour marathon, not 5:41 per km.
How much carbohydrate should I take during a marathon?
At 30–60 g an hour, a 4-hour run means 120–240 g in all. A typical gel carries 20–25 g, so read the packet.