Race split calculator
Every kilometre split and cumulative time for your target, evenly paced or with a deliberate negative split. Write the cumulative column on your arm and stop doing arithmetic at 30 km.
5:41MIN /KM
A finish time is a wish until it is a row of splits. 5:41 per kilometre, every kilometre, is what 2:00:00 over the half marathon costs — and the mark that decides it is halfway, at 1:00:00 on the clock. Change the target below and the band's arithmetic changes with it — the ruler underneath is the sub-2:00 version, drawn on the server so it is there with the script off.
COMPUTED·7,200 s ÷ 21.0975 km, then × each kilometre mark·NOT AN ESTIMATE, NOT A MODEL·WORKING CHECKED JUL 2026
| Split | Pace /km | Elapsed | Pace /mile |
|---|---|---|---|
| Nothing on the band yet — set a distance and a target time. | |||
How the band is printed, mark by mark
- Take the target off the stub and turn it into seconds. Two hours is 7,200.
- Divide by the official distance in kilometres — 21.0975 for the half, 42.195 for the marathon, never the rounded ones. That quotient is the pace you have to hold, in seconds per kilometre.
- Multiply that pace by each kilometre mark in turn. Those products are the cumulative clock readings printed against the ticks — the numbers you compare your watch to, rather than dividing under fatigue.
- Convert once for the units you race in: ×1.609344 for a mile, 3,600 ÷ pace for km/h.
- Scale the splits so they sum to the target exactly, so no rounding drift accumulates across 42 ticks.
pace/km = target seconds ÷ distance km split(k) = pace/km × k (k = 1 … n, cumulative) halfway = target seconds ÷ 2 pace/mile = pace/km × 1.609344 km/h = 3600 ÷ pace/km
Half marathon bands
Rendered on the server, so they work with JavaScript off and print cleanly. Even pacing throughout.
| Point | 1:30:00 | 1:45:00 | 2:00:00 | 2:15:00 | 2:30:00 |
|---|---|---|---|---|---|
| Pace needed /km | 4:16 | 4:59 | 5:41 | 6:24 | 7:07 |
| 5 km | 0:21:20 | 0:24:53 | 0:28:26 | 0:32:00 | 0:35:33 |
| 10 km | 0:42:40 | 0:49:46 | 0:56:53 | 1:03:59 | 1:11:06 |
| Halfway (10.5 km) | 0:45:00 | 0:52:30 | 1:00:00 | 1:07:30 | 1:15:00 |
| 15 km | 1:03:59 | 1:14:39 | 1:25:19 | 1:35:59 | 1:46:39 |
| 20 km | 1:25:19 | 1:39:32 | 1:53:45 | 2:07:59 | 2:22:12 |
| Finish | 1:30:00 | 1:45:00 | 2:00:00 | 2:15:00 | 2:30:00 |
COMPUTED·target ÷ 21.0975 km, then × each mark; splits scaled to sum to the target exactly·NOT AN ESTIMATE, NOT A MODEL·WORKING CHECKED JUL 2026
Marathon bands
| Point | 3:00:00 | 3:30:00 | 4:00:00 | 4:30:00 | 5:00:00 |
|---|---|---|---|---|---|
| Pace needed /km | 4:16 | 4:59 | 5:41 | 6:24 | 7:07 |
| 5 km | 0:21:20 | 0:24:53 | 0:28:26 | 0:32:00 | 0:35:33 |
| 10 km | 0:42:40 | 0:49:46 | 0:56:53 | 1:03:59 | 1:11:06 |
| 15 km | 1:03:59 | 1:14:39 | 1:25:19 | 1:35:59 | 1:46:39 |
| 20 km | 1:25:19 | 1:39:32 | 1:53:45 | 2:07:59 | 2:22:12 |
| Halfway (21.1 km) | 1:30:00 | 1:45:00 | 2:00:00 | 2:15:00 | 2:30:00 |
| 25 km | 1:46:39 | 2:04:25 | 2:22:12 | 2:39:58 | 2:57:45 |
| 30 km | 2:07:59 | 2:29:18 | 2:50:38 | 3:11:58 | 3:33:18 |
| 35 km | 2:29:18 | 2:54:11 | 3:19:05 | 3:43:58 | 4:08:51 |
| 40 km | 2:50:38 | 3:19:05 | 3:47:31 | 4:15:57 | 4:44:24 |
| Finish | 3:00:00 | 3:30:00 | 4:00:00 | 4:30:00 | 5:00:00 |
COMPUTED·target ÷ 42.195 km, then × each mark; splits scaled to sum to the target exactly·NOT AN ESTIMATE, NOT A MODEL·WORKING CHECKED JUL 2026
Why the first five kilometres decide the race
The most common way to miss a target is to be 90 seconds ahead of schedule at 10 km. It feels like insurance. It is not — it is a debt at an appalling rate of interest, and in a warm Indian race it comes due somewhere between 25 and 32 km, in the form of a pace that collapses by a minute a kilometre and never comes back.
The mechanism is not mysterious. Running faster than your sustainable pace burns a disproportionately larger share of carbohydrate and raises core temperature faster; both of those bills are paid later, and neither can be repaid mid-race. Thirty seconds banked early has never once been worth the four minutes it costs.
So: use the negative-split option, take the first two kilometres deliberately slower than goal pace, and let the pace come to you. In a start as crowded as a big Indian city race, the first kilometre will be slow whether you plan it or not — planning it is simply the version where you do not then spend the second kilometre sprinting to make it up.
Questions the band gets asked
What is a negative split?
Running the second half of a race faster than the first. It is the pacing pattern behind most well-run distance races, because starting two per cent slower than goal pace costs very little and starting two per cent fast costs a great deal in the last quarter.
Should I run even splits or negative splits?
Even splits are the sane default and what this calculator produces unless you ask otherwise. A deliberate two per cent negative split is a good plan on a flat course in warm conditions, which describes most Indian races. A positive split — going out fast — is almost never a plan; it is what happens when there is no plan.
How do I use a split chart during a race?
Write the cumulative times, not the per-kilometre paces, on your arm or on a wristband. Under fatigue, comparing your watch's elapsed time to a written number is reliable; doing division is not.
Do the splits account for hills?
No. This is even-effort arithmetic on a flat course. On a course like the Hyderabad Marathon or the Satara Hill Half, plan by effort and expect the uphill kilometres to be slower and the downhill ones faster than the chart.
Every time, pace and physiological figure on this site is computed from a published formula, and the formula is named and shown on the method page. Nothing here is predicted by a model you cannot check. Race details change — always confirm dates, routes and entry with the official organiser. Training guidance is general information, not individual coaching or medical advice.
SOURCE·Race calendars + pace computation·REVIEWED JUL 2026
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