1:21 half marathon pace
A 1:21 half marathon is 3:50/km (6:11/mi), 15.6 km/h.
| Change | Time | Pace |
|---|---|---|
| −2:00 | 1:19:00 | 3:456:02 |
| −1:30 | 1:19:30 | 3:466:04 |
| −1:00 | 1:20:00 | 3:486:06 |
| −0:30 | 1:20:30 | 3:496:08 |
| Your target /km | ||
| +0:30 | 1:21:30 | 3:526:13 |
| +1:00 | 1:22:00 | 3:536:15 |
| +1:30 | 1:22:30 | 3:556:18 |
| +2:00 | 1:23:00 | 3:566:20 |
Arrow keys nudge the value. Hold Shift for bigger steps.
Finish times at 3:50 per km
| Distance | Finish time |
|---|---|
| 1K | 3:50 |
| 1 mile | 6:11 |
| 5K | 19:12 |
| 10K | 38:24 |
| 10 miles | 1:01:47 |
| Half marathon | 1:21:00 |
| Marathon | 2:42:00 |
| 50K | 3:11:58 |
Splits for a 1:21 half marathon
| km | Split | Elapsed |
|---|---|---|
| 1 | 3:50 | 3:50 |
| 2 | 3:50 | 7:41 |
| 3 | 3:50 | 11:31 |
| 4 | 3:50 | 15:21 |
| 5 | 3:50 | 19:12 |
| 6 | 3:50 | 23:02 |
| 7 | 3:50 | 26:53 |
| 8 | 3:50 | 30:43 |
| 9 | 3:50 | 34:33 |
| 10 | 3:50 | 38:24 |
| 11 | 3:50 | 42:14 |
| 12 | 3:50 | 46:04 |
| 13 | 3:50 | 49:55 |
| 14 | 3:50 | 53:45 |
| 15 | 3:50 | 57:35 |
| 16 | 3:50 | 1:01:26 |
| 17 | 3:50 | 1:05:16 |
| 18 | 3:50 | 1:09:06 |
| 19 | 3:50 | 1:12:57 |
| 20 | 3:50 | 1:16:47 |
| 21 | 3:50 | 1:20:38 |
| Final 0.098 km | 0:22 | 1:21:00 |
| Mile | Split | Elapsed |
|---|---|---|
| 1 | 6:11 | 6:11 |
| 2 | 6:11 | 12:21 |
| 3 | 6:11 | 18:32 |
| 4 | 6:11 | 24:43 |
| 5 | 6:11 | 30:54 |
| 6 | 6:11 | 37:04 |
| 7 | 6:11 | 43:15 |
| 8 | 6:11 | 49:26 |
| 9 | 6:11 | 55:37 |
| 10 | 6:11 | 1:01:47 |
| 11 | 6:11 | 1:07:58 |
| 12 | 6:11 | 1:14:09 |
| 13 | 6:11 | 1:20:19 |
| Final 0.109 mi | 0:41 | 1:21:00 |
What a 1:21 half marathon predicts
Estimate| Distance | Estimated time |
|---|---|
| 5K | 17:36 |
| 10K | 36:43 |
| 10 miles | 1:00:48 |
| Marathon | 2:48:53 |
These are estimates from the Riegel formula, T2 = T1 × (D2 ÷ D1)^1.06. They assume you’ve trained for the other distance, so treat them as a guide, not a promise.
From 1:10 to 1:25, the middle kilometres decide it
The opening kilometres feel controlled. The race is decided between 10 and 16 km, when holding pace starts to hurt and the finish is still a long way off.
Tempo runs and threshold intervals do most of the work, with a long run each week.
A gel around halfway is worth testing in training. Some runners race this fast without one; find out which suits you before race day.
Pace questions runners ask
- What pace do I need for a 1:21 half marathon?
- A 1:21 half marathon is 3:50/km (6:11/mi), 15.6 km/h, held for the whole race.
- What treadmill speed is 1:21 half marathon pace?
- Set the treadmill to 15.6 km/h or 9.7 mph to run 3:50/km (6:11/mi).
- Where should I be at halfway in a 1:21 half marathon?
- With even pacing you pass halfway in 40:30; with a negative split, a little later.
- What does a 1:21 half marathon predict for other distances?
- The Riegel formula estimates 17:36 for the 5K, 36:43 for the 10K, 1:00:48 for the 10-mile race, 2:48:53 for the marathon, assuming you’ve trained for each distance.