How marathon time is calculated
A marathon is 26.2 miles, so finish time = pace per mile × 26.2. At a 9:00 pace that is 9 × 26.2 = 235.8 minutes, or 3:55:48. The total minutes are converted into hours, minutes, and seconds.
The official marathon distance is 42.195 km, which is 26.2 miles to one decimal place, and that is the figure used here. Because the multiplier is large, small pace changes matter more than runners expect: ten seconds per mile is 262 seconds, or about four and a half minutes across the whole race.
How to use this calculator
Enter your steady pace in minutes per mile and the tool projects your finish over the full marathon distance. Not sure of your pace? Work it out first with the running pace calculator.
Pace-to-finish reference at an even effort: 7:00 per mile is 3:03:24, 8:00 is 3:29:36, 9:00 is 3:55:48, 10:00 is 4:22:00 and 11:00 is 4:48:12. To go the other way and find the pace a goal time needs, divide the goal in minutes by 26.2 — a 4:00:00 target is 240 ÷ 26.2 = 9.16 minutes, or about 9:09 per mile.
Why projections drift
This assumes an even pace for all 26.2 miles. In reality many runners slow in the later miles, so a projected time is a best-case target. Training to hold pace — and fueling well — is what closes the gap between projection and result.
The usual reason a real finish lands behind the projection is the last 10 km. Glycogen stores hold roughly 90 to 120 minutes of hard running, so most runners need 30 to 60 g of carbohydrate an hour from about the first hour onward. Course profile and heat matter too — a rule of thumb is a 2 to 3% slowdown for every 5°C above about 12°C.
Treat the projection as a discipline check: run the first mile at the projected pace rather than faster, and if your long runs cannot hold it, the number is a stretch goal rather than a plan. Confirm the pace itself with the running pace calculator, or convert it into miles per hour with the running speed calculator.
Frequently asked questions
- How do I calculate marathon finish time?
- Multiply your per-mile pace by 26.2. A 9:00 pace gives 9 × 26.2 = 235.8 minutes, or 3:55:48.
- Is an even-pace projection realistic?
- It is an ideal. Many runners fade late, so treat the projection as a target rather than a guarantee.
- What pace do I need to break 4 hours?
- About 9:09 per mile or faster. Roughly a 9:00 pace finishes just under 3:56.
- Does this work for a half marathon?
- Multiply your pace by 13.1 instead of 26.2 for a half marathon projection.
- Why is my GPS distance longer than 26.2 miles?
- Marathon courses are measured along the shortest legal line, and almost nobody runs it — weaving between runners and taking wide corners typically adds 1 to 2%. Running 26.5 miles at your goal pace costs about three extra minutes, so run the tangents where you can.