Marathon and Half Marathon Pace Band Calculator
Marathon and Half Marathon Pace Band Calculator
A target finishing time turned into the band a runner prints: the clock reading at every five-kilometre mark, at halfway, and at the mile landmark that falls between two of them. The headline is the 20-mile clock for a marathon and the 10-mile clock for a half.
The clock at the mile landmark, and the whole band beneath it
Target time to marksA 3:30:00 marathon
Formula
clock at a mark = pace per km × (mark in metres ÷ 1000)
pace per mile = pace per km × 1.609344
clock at the mile landmark = pace per mile × 20 (marathon) or × 10 (half)
- 42,195 and 21,097.5
- World Athletics’ own marathon discipline page gives the distance as “26 miles and 385 yards (42.195km)” and records that “this distance was standardised at 26 miles 385 yards (42.195km) in 1921”. The half marathon is exactly half, which is why it carries a half metre and its halfway point a quarter
- 32,186.88 m
- twenty miles, exactly, at 1,609.344 m to the mile. The mile is definitional: the yard is 0.9144 m by the 1959 definition NIST records, and a mile is 1,760 yards. No governing body makes 20 miles a mark — it is a convention of marathon running, and it is on this page because that is the figure people ask for
- even pace is an assumption
- every row is the pace held exactly from the gun. Nobody does that. A band’s value is that it makes the deviation visible, not that the schedule is achievable
- the marks are not all official
- the five-kilometre marks are where intermediate times are conventionally taken on a road course, and halfway is a marked point. The mile landmarks are a runner’s convention. Nothing in this list is a regulation about where a clock must be
- the course is longer than your watch thinks
- a certified course is measured along the shortest possible route and carries a 0.1% short course prevention factor, so a certified 10 km is a physical 10,010 m and a GPS trace of a race almost always reads long. A band keyed to kilometre marks on the road is right; the same band keyed to a watch’s own kilometre alerts drifts
Worked example
A 3:30:00 marathon
3:30:00 is 12,600 seconds and the marathon is 42.195 km, so the pace is 12,600 ÷ 42.195 = 298.6 seconds per kilometre
298.6 × 1.609344 = 480.6 seconds per mile
Twenty miles is 32,186.88 m, so the landmark clock is 480.6 × 20 = 9,611.4 seconds, which splits as 2 hours 40 minutes 11 seconds
Each five-kilometre segment is 298.6 × 5 = 1,493.1 seconds, or 24:53, so the band steps by the same figure every time
Halfway is 6,300.0 seconds, 1:45:00 exactly — half of any even-paced target always is
The 30 km clock is 8,958.4 seconds, 2:29:18, and the 35 km clock 10,451.5, so the 20-mile landmark at 2:40:11 sits between them, which is the reason it gets its own row
Switch the race to a half marathon and the 25 km, 30 km, 35 km and 40 km rows disappear, because the race does not reach them
Set the target to zero and the panel stays empty, because there is no band
The printed band, marathon
| Target | 5 km | 10 km | 15 km | 20 km | 25 km | 30 km | 35 km | 40 km |
|---|---|---|---|---|---|---|---|---|
| 2:30:00 | 17:46 | 35:32 | 53:19 | 1:11:05 | 1:28:52 | 1:46:38 | 2:04:25 | 2:22:11 |
| 3:00:00 | 21:19 | 42:39 | 1:03:59 | 1:25:19 | 1:46:38 | 2:07:58 | 2:29:18 | 2:50:38 |
| 3:30:00 | 24:53 | 49:46 | 1:14:39 | 1:39:32 | 2:04:25 | 2:29:18 | 2:54:11 | 3:19:04 |
| 4:00:00 | 28:26 | 56:52 | 1:25:19 | 1:53:45 | 2:22:11 | 2:50:38 | 3:19:04 | 3:47:30 |
| 4:30:00 | 31:59 | 1:03:59 | 1:35:58 | 2:07:58 | 2:39:58 | 3:11:57 | 3:43:57 | 4:15:57 |
| 5:00:00 | 35:32 | 1:11:05 | 1:46:38 | 2:22:11 | 2:57:44 | 3:33:17 | 4:08:50 | 4:44:23 |
Where the mile landmarks fall, and why they need their own rows
| Landmark | In metres | Between which kilometre marks | Clock at 3:30 marathon pace |
|---|---|---|---|
| 10 miles | 16,093.44 | 15 km and 20 km | 1:20:05 |
| Half marathon distance | 21,097.50 | 20 km and 25 km | 1:45:00 |
| 20 miles | 32,186.88 | 30 km and 35 km | 2:40:11 |
| 25 km | 25,000.00 | a kilometre mark itself | 2:04:25 |
| Marathon distance | 42,195.00 | beyond 40 km | 3:30:00 |
A target time, and the band it implies
This page is about athletics — track and field, and road running — whose competition rules, technical rules and scoring tables are published by World Athletics, the body that was the IAAF until 2019. Where a figure below belongs to a particular edition of those rules, the edition is named beside it, because World Athletics revises them and a number quoted without its edition will be wrong for somebody.
This is not the pace calculator with a longer answer, and the difference is worth being explicit about because this category already has two pages about pace. The running pace calculator turns a finished race into the pace it was run at. The race split times calculator goes the other way, from a pace you intend to hold to a finishing time and a pair of halves. This page starts from a target finishing time and returns the thing a runner actually prints and pins to a wrist: the clock reading at every mark on the course, including the mile landmarks that fall at awkward kilometres and the 30 km point where a marathon is decided. None of those marks is computed on either of the other two pages.
The arithmetic is a division and then eight multiplications. A 3:30:00 marathon is 12,600 seconds over 42.195 kilometres, which is 298.6 seconds for each one, which is 4 minutes 58.6 seconds; multiply that by five and the band steps 24:53 at a time. What makes a band worth printing rather than working out in your head mid-race is the cumulative column: at 30 km the clock should read 2:29:18, and knowing that is useful at a moment when multiplying 298.6 by thirty is not.
A note on how the clock readings are shown. The calculator is numeric: it has no text type, so it cannot print a colon and there is no 2:40:11 for it to show. Every figure in the band is in seconds, and the headline’s hours, whole minutes and remaining seconds are the three rows directly beneath it — 9,611.4 seconds, then 2, 40 and 11. The split is taken on the rounded whole second rather than on the raw value, which matters more than it looks: a landmark clock of 9,659.6 seconds split before rounding reads 2 hours 40 minutes and 60 seconds, and rounding first makes it 2 hours 41 minutes 0 seconds.
The mile landmarks are the reason this page has a headline of its own. Twenty miles is 32,186.88 metres, which falls between the 30 km and 35 km marks and therefore cannot be read off a kilometre band at all. In marathon running it is the figure people actually quote — the point at which there are ten kilometres left and the race is usually decided — and in a half marathon ten miles plays the same role. The mile is exactly 1,609.344 metres, 1,760 yards at 0.9144 m to the yard by the 1959 definition that NIST records, so the conversion is definitional and exact and belongs to no governing body.
The distances themselves do belong to one. World Athletics’ marathon discipline page gives the race as “26 miles and 385 yards (42.195km)” and dates the standardisation to 1921; the half marathon is exactly half of that, which is why it is 21,097.5 m and its halfway point 10,548.75 m. The five-kilometre marks, by contrast, are a convention rather than a regulation: nothing in the rules says where a clock must be, and a race may mark miles, kilometres or both.
One thing a band cannot fix, and it is worth knowing before you blame the band. A certified road course is measured along the shortest possible route a runner could take, and certification builds in a short course prevention factor of 0.1%, so a certified 10 km is laid out as a physical 10,010 m. Add the fact that nobody runs the shortest possible route and a watch will read long on almost every race. The band is right against the marks painted on the road and drifts against a watch’s own kilometre alerts, which is a reason to run to the marks. The road race course measurement calculator has the method and the factor’s direction.
Where the line runs between this page and the health section: health owns the athlete’s body and this page owns the race. A figure derived from a person — aerobic capacity, a heart-rate zone, a body composition — is there, at the VO2 max calculator and the target heart-rate zones calculator. A figure derived from a clock and a distance is here. Nothing on this page prescribes a training pace or a heart rate, or makes any physiological claim.
Nothing here is a plan. The page computes what an even pace would produce and no governing body publishes a pace distribution for anybody; the race split times calculator will build you two halves on a negative split if you want to see what one implies, and the percentage in that field is yours too. For what a result at one distance suggests about another, the race time predictor does Riegel’s arithmetic and prints what is wrong with it.
Frequently asked questions
What pace do I need for a 3:30 marathon?
298.6 seconds per kilometre, which is 4 minutes 58.6 seconds, or 480.6 seconds per mile, which is 8 minutes 0.6 seconds. 12,600 seconds divided by 42.195 km. The 20-mile clock is 2:40:11 and halfway is 1:45:00.
Where does the 20-mile mark fall in kilometres?
At 32,186.88 m, between the 30 km and 35 km marks. The mile is exactly 1,609.344 m, so no mile landmark coincides with a kilometre mark — which is why a kilometre band cannot give you a 20-mile split and this page prints it separately.
Is the halfway split always half the target?
At an even pace, yes, exactly — 1:45:00 for a 3:30 target — because half the distance at a constant pace takes half the time. That is a property of the assumption, not of racing: a real halfway split that is exactly half the finishing time is a coincidence.
Why does my watch disagree with the band?
Because a certified course is measured along the shortest possible route a runner could take, with a 0.1% short course prevention factor built in, and you did not run that route. A certified 10 km is a physical 10,010 m before you add a single extra metre of your own. Run to the marks on the road rather than to the watch.
Why is the half marathon 21,097.5 m rather than 21,100?
Because it is exactly half the marathon, and World Athletics gives the marathon as 42.195 km, standardised in 1921 at 26 miles 385 yards. Half of 42,195 is 21,097.5, and half of that — the halfway point of a half marathon — is 10,548.75 m.
Does this page tell me how to pace the race?
No. It tells you what an even pace produces. No governing body publishes a pace distribution and this page does not invent one; there is no training advice here and nothing about effort, fuelling or heart rate.
Related calculators
References
- World Athletics. “Marathon” discipline page, worldathletics.org (read 12 Oct 2026; about 20,000 characters, much of it navigation). “Athletes run a distance of 26 miles and 385 yards (42.195km)”, and “this distance was standardised at 26 miles 385 yards (42.195km) in 1921”.
- National Institute of Standards and Technology. “SI Units — Length”, Office of Weights and Measures, nist.gov (read 12 Oct 2026). Records the 1958 agreement by which “a conference of English-speaking nations agreed to unify their standards of length and mass” and the 1959 Federal Register Notice 59-5442 of 30 June 1959 making the inch “exactly equivalent to 25.4 mm”, with a conversion equation giving 0.9144 m to the yard. The page does not state the mile in words, so the 1609.344 m used here is 1760 × 0.9144 m and is exact by that definition rather than quoted.
- Cundy, Dave, and Hugh Jones. The Measurement of Road Race Courses, second edition 2004, updated 2008, published jointly by the IAAF and the Association of International Marathons and Distance Races; read 15 Oct 2026 from the copy on media.aws.iaaf.org (roughly 70,000 to 80,000 characters, the data sheets cut off at the end). Cited here for two statements only: the then-current IAAF Rule 240.3, “In events on roads the course shall be measured along the shortest possible route that an athlete could follow” with “the uncertainty in the measurement shall not exceed 0.1% (i.e. 42m for the Marathon)”; and the short course prevention factor, “For bicycle measurements this factor should be 0.1% which means that each km on the course will have a ‘measured length’ of 1001m.” The full entry, with the method and both worked examples, is on the measurement page.
- World Athletics. Technical Rules (Book C, C2.1), copy read 12 Oct 2026 carrying amendments effective 1 January 2022; about 60,000 characters of readable text, truncated before the combined-events material. A time is recorded “to the next longer 0.01 second” for races up to and including 10,000m, and a hand time “to the next longer 0.1 second” — in both cases away from the athlete rather than to the nearest.