What pace runs a 4-hour marathon?

Target paces

A marathon is 42.195 km (26.2 miles), the distance set by World Athletics. To finish in 4:00:00 you need 4 × 3600 ÷ 42.195 = 341 seconds per km, which is 5:41 per km or 9:09 per mile, about 10.5 km/h. For 3:30:00 the pace is 4:59 per km (8:01 per mile). For a 1:55 half marathon it is 5:27 per km.

The pace calculator converts any finish time to a pace per km and per mile, and shows what that pace means over 5K, 10K and the half.

Is the goal realistic?

Shorter race results are the best guide. Most runners slow by several seconds per km as the distance doubles, so a 10K run at 5:30 per km (55:00) usually points to a marathon somewhat slower than 5:41 per km, especially for a first attempt. If your recent 10K pace is slower than your marathon target, the target is likely too fast for now.

Training runs at goal pace tell you more than any formula: if you can hold the pace for 15 to 20 km in training while still able to talk in short sentences, the plan is on track.

Pacing the day

Even pacing is the safe plan. Starting 10 seconds per km faster than goal feels easy in the first 10 km and often costs minutes after 30 km. Many runners aim for an even or slightly faster second half (a negative split). Check your watch at each 5 km against the split times for your goal, and allow for crowded starts, hills, heat and drink stations, which a steady-pace calculation does not include.

Kilometers or miles

Course markers may be in either unit. A mile is exactly 1.609344 km, so a pace per km times 1.609344 gives the pace per mile: 5:41 per km is 9:09 per mile. Switch the unit in the calculator so the splits match the markers on your course.

After the race

Enter your actual time to get your real average pace, then use it to set the next goal. A good next target is often a few seconds per km faster, not minutes, and the time from your latest half marathon is a better guide than your best marathon from years ago.

Splits for a 4-hour marathon

At 5:41 per km the 5 km checkpoints come at about 28:26, 56:53, 1:25:19 and 1:53:45 for 20 km, with halfway (21.1 km) at 2:00:00. In miles, 9:09 per mile puts you at about 45:46 after 5 miles and 1:31:32 after 10. Write the checkpoints for your own goal on a pace band, or set the watch to show the average pace for the current kilometer.

Training paces from the goal

Most training should be slower than goal pace, at an easy conversational effort, with a weekly long run building toward 30 to 32 km. Goal-pace sections within long runs teach the rhythm of race day. If those sections feel hard to hold for 10 km, the goal is probably a little ambitious, and a 4:10 target with an even pace is a better plan than a 4:00 target that falls apart.

In short

Divide the goal time by 42.195 km to get the pace, check it against a recent shorter race, and train at that pace in sections of your long runs. On the day, start no faster than goal pace and use split times at each 5 km. Afterwards, enter your real time to set a realistic next target, and give yourself a few weeks of easy running before training hard again. The same method works for any distance, from a first 5K to an ultramarathon.