Boston Marathon 3:45 pace chart
A 3:45:00 finish at the Boston Marathon averages 8:35 per mile (5:20 per kilometre) — a fast recreational time, roughly the top quintile of a big-city field. Run at even effort rather than even pace, the easiest mile comes in around 7:50/mi and the hardest around 9:34/mi — about 104 seconds between the two extremes. Holding an identical number on every mile of a course with this profile means running the climbs too hard and the descents too easy. Held at even effort, halfway comes up at 1:51:36 — a 1:48 positive split, which is what the terrain costs you rather than a pacing error. The hardest mile on the course sits near kilometre 33; at this goal time it should take 9:34/mi, and giving it that time is the difference between finishing Boston on plan and unravelling in the last hour.
Mile-by-mile targets for 3:45:00
Grade-adjusted splits computed from the Boston Marathon elevation profile with the Minetti gradient-cost model, scaled so the full course adds up to 3:45:00. Uphill sections get more time, downhills less, at one constant effort throughout.
| Mile | Target /mi | Target /km | Elev Δ | Elapsed |
|---|---|---|---|---|
| 1 | 7:55 | 4:55 | -107 ft (-33 m) | 7:55 |
| 2 | 8:14 | 5:07 | -57 ft (-17 m) | 16:09 |
| 3 | 8:15 | 5:08 | -56 ft (-17 m) | 24:24 |
| 4 | 8:12 | 5:06 | -59 ft (-18 m) | 32:36 |
| 5 | 8:49 | 5:29 | +11 ft (+3 m) | 41:25 |
| 6 | 8:30 | 5:17 | -25 ft (-8 m) | 49:54 |
| 7 | 8:36 | 5:20 | -12 ft (-4 m) | 58:30 |
| 8 | 8:43 | 5:25 | -1 ft (0 m) | 1:07:14 |
| 9 | 8:38 | 5:22 | -8 ft (-2 m) | 1:15:52 |
| 10 | 8:51 | 5:30 | +16 ft (+5 m) | 1:24:43 |
| 11 | 8:56 | 5:33 | +26 ft (+8 m) | 1:33:39 |
| 12 | 8:15 | 5:08 | -54 ft (-16 m) | 1:41:54 |
| 13 | 8:45 | 5:26 | +5 ft (+1 m) | 1:50:39 |
| 14 | 8:40 | 5:23 | -5 ft (-2 m) | 1:59:19 |
| 15 | 8:54 | 5:32 | +22 ft (+7 m) | 2:08:13 |
| 16 | 7:50 | 4:52 | -110 ft (-33 m) | 2:16:03 |
| 17 | 9:16 | 5:45 | +57 ft (+17 m) | 2:25:19 |
| 18 | 9:08 | 5:41 | +41 ft (+13 m) | 2:34:27 |
| 19 | 8:26 | 5:14 | -31 ft (-9 m) | 2:42:53 |
| 20 | 8:58 | 5:34 | +25 ft (+7 m) | 2:51:51 |
| 21 | 9:34 | 5:57 | +88 ft (+27 m) | 3:01:24 |
| 22 | 8:04 | 5:01 | -78 ft (-24 m) | 3:09:29 |
| 23 | 8:20 | 5:11 | -44 ft (-14 m) | 3:17:49 |
| 24 | 8:15 | 5:07 | -54 ft (-17 m) | 3:26:04 |
| 25 | 8:22 | 5:12 | -39 ft (-12 m) | 3:34:26 |
| 26 | 8:43 | 5:25 | +2 ft (+1 m) | 3:43:09 |
| 26.2 | 8:29 | 5:16 | -5 ft (-2 m) | 3:45:00 |
Frequently asked questions
What pace is a 3:45 marathon?
A 3:45:00 marathon is 8:35 per mile or 5:20 per kilometre held for the full 26.2 miles (42.195 km). On the Boston Marathon specifically, the elevation profile means even effort produces uneven splits — the table on this page gives the target for every mile.
What should my halfway split be for a 3:45 at the Boston Marathon?
1:51:36. That is the grade-adjusted halfway target for this course, not simply half of 3:45:00 — it accounts for where the climbing sits. Reaching the half meaningfully faster than this on this course usually means you have spent the effort you need for the closing miles.
Should I run even splits at the Boston Marathon?
Even effort at a 3:45 goal produces splits between 7:50 and 9:34 per mile — about 104 seconds between the easiest and hardest one. Grade-adjusted pacing gives back time on the descents and spends it on the climbs, which is what running an even physiological effort actually looks like on a course with this profile.
How are these Boston Marathon splits calculated?
Each mile is weighted by its gradient using the Minetti et al. (2002) cost-of-running polynomial, which measures the metabolic cost of running at grades from −45% to +45%. The total is then scaled so the whole course adds up to 3:45:00. Uphill sections get more time and downhill sections less, at a constant effort throughout.
Is 3:45 a realistic marathon goal?
3:45 is a fast recreational time, roughly the top quintile of a big-city field. Whether it is realistic for you depends on your recent race results and weekly volume rather than on the number itself — the race-time predictor on this site will convert a recent 5K, 10K or half-marathon result into a marathon estimate using the Riegel power-law model.