Race Split Calculator: free race pace and splits calculator.
Pick your race and your target time. Get your split for every km or mile, even or negative, and a pace band to print.
Your splits
Marathon · 3:30:00
First half
5:02/km
1:46:04
Second half
4:56/km
1:43:56
The second half is 2% quicker than the first. Average pace 4:59 per km.
Every km: the split, then the time on the clock. The dot marks halfway.
- 15:025:02
- 25:0210:03
- 35:0215:05
- 45:0220:07
- 55:0225:08
- 65:0230:10
- 75:0235:11
- 85:0240:13
- 95:0245:15
- 105:0250:16
- 115:0255:18
- 125:021:00:20
- 135:021:05:21
- 145:021:10:23
- 155:021:15:24
- 165:021:20:26
- 175:021:25:28
- 185:021:30:29
- 195:021:35:31
- 205:021:40:33
- 215:021:45:34
- 224:561:50:30
- 234:561:55:26
- 244:562:00:22
- 254:562:05:17
- 264:562:10:13
- 274:562:15:08
- 284:562:20:04
- 294:562:25:00
- 304:562:29:55
- 314:562:34:51
- 324:562:39:46
- 334:562:44:42
- 344:562:49:38
- 354:562:54:33
- 364:562:59:29
- 374:563:04:24
- 384:563:09:20
- 394:563:14:16
- 404:563:19:11
- 414:563:24:07
- 424:563:29:02
- 42.20:583:30:00
Pace band to print
- 1 km5:02
- 2 km10:03
- 3 km15:05
- 4 km20:07
- 5 km25:08
- 6 km30:10
- 7 km35:11
- 8 km40:13
- 9 km45:15
- 10 km50:16
- 11 km55:18
- 12 km1:00:20
- 13 km1:05:21
- 14 km1:10:23
- 15 km1:15:24
- 16 km1:20:26
- 17 km1:25:28
- 18 km1:30:29
- 19 km1:35:31
- 20 km1:40:33
- 21 km1:45:34
- 22 km1:50:30
- 23 km1:55:26
- 24 km2:00:22
- 25 km2:05:17
- 26 km2:10:13
- 27 km2:15:08
- 28 km2:20:04
- 29 km2:25:00
- 30 km2:29:55
- 31 km2:34:51
- 32 km2:39:46
- 33 km2:44:42
- 34 km2:49:38
- 35 km2:54:33
- 36 km2:59:29
- 37 km3:04:24
- 38 km3:09:20
- 39 km3:14:16
- 40 km3:19:11
- 41 km3:24:07
- 42 km3:29:02
- 42.2 km3:30:00
Hand it to your AI
Your AI can check these numbers against your training and adjust them. The prompt has your results filled in.
See the prompt
I'm aiming for 3:30:00 in a Marathon. A race split calculator gave me a negative split, second half 2% faster: 5:02 per km for the first half (1:46:04), then 4:56 per km (1:43:56). Look at my recent training and tell me if this target and split are realistic for me, and how to pace the start, the hills and the last part.
Gemini, Grok Bot, Dots, Muse and Cue: copy the prompt and paste it in.
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How it works
How the Race Split Calculator works.
Your target time divided by the distance gives your average pace. Run that pace from start to finish and you have even splits: every km or mile in the same time.
A negative split means running the second half faster than the first. Pick how much faster, from 1 to 3%, and the calculator shares out your target time so the two halves add up exactly. With a 2% negative split, the second half takes 98% of the time of the first.
Within each half the pace is steady, so the km or mile that crosses halfway mixes the two paces. The last split is the part of a km or mile left at the end, like the final 195 m of a marathon.
Each row shows the split for that km or mile and the time on the clock when you pass its marker. The pace band holds the clock times, small enough to wear. Press Print and only the band prints. Cut it out and tape it around your wrist.
The numbers are pure arithmetic. Whether a target and a split strategy suit you is a question for your training, your course and the weather on the day. Your AI can look at your recent runs and tell you how realistic it is.
The formula
- even: pace = target time ÷ distance
- negative: first half = target ÷ (2 − x), second half = target − first half, where x is the share faster (0.02 for 2%)
Example
A worked example.
A runner aiming for a 3:30:00 marathon with the second half 2% faster.
- 1The first half takes 1:46:04 and the second 1:43:56, which is 2% less.
- 2That is 5:02 per km for the first half and 4:56 per km for the second. The average is 4:59 per km.
- 3On the clock: 50:16 at 10 km, 1:45:34 at 21 km, 2:29:55 at 30 km and 3:29:02 at 42 km. The last 195 m bring it to 3:30:00.
- 4Run evenly instead and every km takes 4:59, or 8:01 per mile.
Questions
Race Split Calculator: questions.
Running the second half of a race faster than the first. Here you choose how much faster, from 1 to 3%, and the splits are worked out so you still finish on your target time.
It depends on you, your course and the conditions. A small negative split is one way to hold yourself back early in the race. Your AI can look at how your past races went and help you choose.
4:59 per km or 8:01 per mile if you run it evenly. With a 2% negative split, 5:02 per km for the first half and 4:56 per km for the second.
Press Print under the pace band. Only the band prints, with the time on the clock at every km or mile. Cut it out, and tape it around your wrist or tuck it under your watch strap.
Yes. Pick Custom and type the distance in km, or in miles with Imperial on.
Not medical advice. These numbers come from published research on groups of athletes. Your own needs can differ; talk to a doctor or a sports dietitian about any health condition.