Marathon Pace Band

What this page does

A marathon pace band is the oldest piece of equipment in distance running: a strip of paper with the kilometre numbers down one side and the clock you should be reading beside each one. You cut it out, fold it, tape it round your wrist, and at 30 km you look at it instead of doing arithmetic. This page builds that strip from a single number you type — your target finish time — and draws the band on screen at the size it will print.

There is no second input. No recent race, no age, no course profile, no start-line gap, no weather. A band answers one question — if I want to finish in this time, what does the clock have to read at every kilometre? — and that question has exactly one input. Everything on the strip falls out of one division, and the page shows you the division rather than hiding it behind a formula name.

It is a different job from the race time predictor, which takes a race you have already run and predicts a finish time you have not. This page does not predict anything: you arrive with the target, and it tells you what that target requires kilometre by kilometre.

How the number is calculated

The arithmetic is one division and one multiplication. The marathon is 42.195 km, so the even pace for a target time T is:

p = T ÷ D where D = 42.195 km (or 26.2188 mi)

T — your target finish time, in seconds. 3:30:00 is 12600 s.
D — the marathon distance: 42.195 km. That figure is the World Athletics road-race standard distance, not a measurement of any one course. In miles it is 42.195 ÷ 1.609344 = 26.2187575 mi, and the 26.2188 printed on the band is that figure rounded to four decimals. 1 mi = 1609.344 m is an exact, defined value, not a measurement.
p — seconds per kilometre (or per mile). For 3:30:00 this is 12600 ÷ 42.195 = 298.6136 s, which prints as 4:59.

Every row on the band is then that pace multiplied by the row's distance:

t_k = p × k t_finish = T

k — the whole-kilometre number: 1, 2, 3 … 42.
t_k — the elapsed clock at that marker, rounded to the nearest second before it is printed.
t_finish — the last row, printed as your target time exactly, with no rounding. The race ends at 42.195 km, so that final row covers a partial segment — see the worked row below.

A worked band: 3:30:00

The demo the page opens on. Take T = 3:30:00 = 12600 s. The even pace is 12600 ÷ 42.195 = 298.6136 s per kilometre, which is 4:58.6 — printed on the band as 4:59. The elapsed column then falls out of the multiplication:

5 km — 5 × 298.6136 = 1493.1 s, printed 24:53.
10 km — 2986.1 s, printed 49:46.
21 km — 6270.9 s, printed 1:44:31.
30 km — 8958.4 s, printed 2:29:18.
42 km — 12541.8 s, printed 3:29:02. Note this is not the finish: 42 km is 195 m short of the line.
Finish, 42.195 km — 3:30:00 exactly. The last segment is 195 m and takes the remaining 58 s.

The halfway point of a marathon is 21.0975 km, which is not between the 21 km and 22 km rows in the way most people expect: it is 97.5 m past the 21 km mark. On even splits the halfway clock is exactly half the target — 1:45:00 for a 3:30:00 goal — and that is the single most useful number on the whole strip.

The band: one target, one column

A marathon pace chart is a grid: distances down one side, a range of finish times across the top, and a pace in every cell. It is a reference document — you look something up in it. A pace band is the opposite object: it collapses the grid to the single row you need and turns it into something you can wear. The whole design difference is in that collapse, so it is worth being exact about what the band contains.

The band has one row per whole kilometre, plus one row for the finish:

Kilometre band — 42 whole-kilometre rows (1 km through 42 km) plus the finish at 42.195 km. 43 rows.
Mile band — 26 whole-mile rows (1 mi through 26 mi) plus the finish at 26.2188 mi. 27 rows.

Note what the last row is not. It is not "43 km" or "27 mi". The race ends at 42.195 km, so the final segment is a partial one — 195 m on the kilometre band, about 35 seconds of running at a 3:30 pace — and the band labels it as the finish and prints your target time on it exactly. Every other row is rounded to the nearest second, so that last row is the one row you can trust to the second without a rounding caveat.

The band prints elapsed, not lap — and that is the point

The table above the band carries both a lap column and an elapsed column. The band carries only elapsed. That is deliberate: on race day you are comparing one number — the total time on your watch — against one number on the band, and you are doing it while breathing hard. A lap column asks you to subtract the previous row from the current one, mid-race, which is exactly the kind of arithmetic that goes wrong at 32 km.

There is a second reason. A cumulative column cannot hide a small error. If you run each kilometre three seconds slow, the band's 10 km row is thirty seconds away from where you are, and it is visibly away. A lap-only band would let ten separate three-second errors sit side by side looking harmless. The band is built so that drift accumulates where you can see it.

The rounding rule, and the bound it gives you

Every whole-marker row is the exact even-split time rounded to the nearest second. Rounding to the nearest second means the gap on any single row cannot exceed half a second in either direction, and the page reports the largest gap that actually occurs on your band. For the 3:30:00 example it is 0.50 s, at the 22 km row, where the exact 6569.4988 s prints as 6569.

That is a stated guarantee rather than a hope, and it is a design choice worth naming: many printed bands round each row to the nearest five seconds, which makes the numbers easier to read at a glance but widens the worst-case gap on a single row to 2.5 s. This page rounds to one second and keeps the half-second bound instead. If you would rather have the five-second band, round each row yourself — the arithmetic is all on this page.

Reading the band on the day

The band is a measuring stick, not a coach. Three things follow from that, and they are the whole of how to use it:

Read the elapsed column at the marker, not between markers. The band has no opinion about the 400 m between kilometre 32 and kilometre 33. It has a firm opinion about the clock at kilometre 33, and that is the number to compare with your watch.
A gap smaller than the rounding bound is not a gap. If the band says 49:46 at 10 km and your watch says 49:46, you are on the band. If it says 49:46 and you are at 49:52, you are six seconds down — real, but small, and the band's job ends at showing you that.
The band does not tell you to catch up. It tells you where you are. Whether to press, hold or ease is a decision about your fitness and the course, and nothing in a table of even splits knows either of those things.

The halfway check is the one row worth marking on the band in pen before you start. Half of 42.195 km is 21.0975 km, and on even splits the halfway clock is exactly half your target — 1:45:00 for a 3:30:00 goal. It sits 97.5 m past the 21 km row (1:44:31). Most big-city marathons have a halfway timing mat; if yours does, that mat and the band should agree to within the rounding bound.

The 30 km row is worth marking too, and for the opposite reason. It is the last row before the part of a marathon where pace is decided by fuel rather than by fitness, and being able to see whether you are on, ahead of or behind the band at that exact line tells you more about your day than any split before it.

One honest caveat sits on top of all of it. Even splits assume the second half is run at the same effort as the first, and the single most common way a marathon goes wrong is a first half run too fast. A band cannot stop that — but it can show it to you at 21 km, which is earlier than most runners notice.

Printing the band at the right size

A pace band that prints at the wrong scale is not a pace band; it is a smaller or larger piece of paper with the same numbers on it. The band is drawn 170 mm wide, and it carries its own scale check: a line marked "this line is 50 mm" near the top. Print the page, then hold a ruler against that line. If it measures 50 mm, the band is the size it was drawn. If it does not, your printer scaled the page and the band is the wrong size.

Set the scale to 100%. Print dialogs default to "fit to page" or "shrink to fit", and both will resize the band. Choose 100%, Actual size, or "none" depending on the dialog. This is the one setting that matters.
A4 and US Letter both work at 100%. The band is 170 mm wide and about 110 mm tall on the kilometre setting, so it fits inside the printable area of either sheet with room to spare.
Fold between the columns. The rows run in three columns of fifteen on the kilometre band: kilometres 1–15, 16–30, and 31–42 plus the finish. Fold twice and the start and the finish end up at opposite ends of the strip.
Cut along the border, then tape the ends. The strip is 170 mm long — about the circumference of an adult wrist — so the two ends meet with a small overlap to tape. If you would rather not wear it, it is the right size to sit flat in a pocket or a race-belt sleeve.
Black and white is fine. Nothing on the band depends on colour; the finish row is a solid block, and it survives a monochrome printer.

If you have no printer to hand, the Download band button writes the same rows to a plain-text file, and Copy pace band puts them on your clipboard. Neither of those is a substitute for the printed strip — a phone in a pocket at 35 km is not a pace band — but the text file is the version to keep, and it reprints identically whenever you want it.

Supported range and limits

Distance: the marathon only — 42.195 km or 26.2188 mi. This is not a general distance calculator; the whole point is that the distance is fixed and the band is built for it.
Target time: 2:00:00 to 47:59:59, in hours, minutes and seconds. Below two hours the page refuses the entry rather than printing a band for a time no marathon has been run in.
Units: kilometres or miles for the band and the table, switchable at any time. The distance behind the two is the same; only the markers move.
Pacing: even splits only. There is no negative-split band, and the reason is in the next section.
Cost: none. No account, no email, no paywall, no daily limit, no request to a server.
Privacy: every number is computed in your browser. Nothing you type is sent anywhere or stored — reload the page and it is gone.
Works offline once the page has loaded, and on a phone.

What this page deliberately does not do

No hill adjustment. The band assumes a flat course and says so on every row. A hilly marathon needs a per-kilometre elevation profile and a published energy-cost model; the marathon split calculator does exactly that job, and this page does not borrow it, because a band that quietly mixes two models is worse than a band that states one.
No prediction. This page never asks for a race you have already run, and it never tells you a finish time. It is the reverse direction: you bring the target, it tells you what the target costs per kilometre. If you want the other direction, the race time predictor on the home page turns one recent result into a predicted finish.
No two clocks. A band carries one column, so there is one clock on it. If your race is chip-timed and you want to know what the gun clock above the markers will read while your watch reads the band, the splits calculator carries both clocks side by side with a start-line-gap estimate.
No half marathon band. Half of a marathon is 21.0975 km, and a band for it is not this band halved — it has its own row count and its own partial finish segment. The half marathon split calculator builds that one.
No negative-split band. A band carries one target time and one number per row; a negative split is a shape, not a target, and printing it needs a model of how much slower the first half should be. That model would be a guess about you, so the page prints the honest version — even splits — and leaves the shape to you.
No aid-station markers. Real bands sometimes mark where the water is. That requires the aid-station positions for one specific race, and this page has no source it can stand behind for any race's layout, so it prints distance markers only.
No course presets. There is no "Boston" or "Berlin" option. A preset would mean shipping a per-kilometre profile for a real course, and courses are re-measured.
No age grading, no weather correction, no watch sync. All three need published tables or a device connection this page does not have. Rather than ship a made-up coefficient, it leaves them out and prints the number it can defend.

Questions

What is a marathon pace band?

A marathon pace band is a strip of paper that carries one row per kilometre of the 42.195 km and, beside each row, the elapsed clock you should be reading at that marker. It is a marathon pace chart collapsed to a single target time and a single column, sized to be cut out and worn. This page builds it from one number you type — your target finish time — and draws the band itself.

How is the pace on the band worked out?

It is one division, repeated. The even pace is your target time in seconds divided by 42.195 km. For a 3:30:00 target that is 12600 s divided by 42.195, which is 298.6136 s per kilometre, printed on the band as 4:59. Each row's clock is that pace multiplied by the kilometre number, so the 10 km row is 2986.1 s, printed 49:46, and the finish row is your target exactly.

Why does the band print elapsed time instead of lap time?

Because on race day you compare one number — the total on your watch — against one number on the band, and you do that while breathing hard. A cumulative column also cannot hide a small error: if you run each kilometre three seconds slow, the 10 km row is thirty seconds away from where you are and it is visibly away, whereas a lap-only band would let ten separate three-second errors sit side by side looking harmless.

How accurate are the times on the band?

Each whole-kilometre row is the exact even-split time rounded to the nearest second, so no row can be more than half a second from the arithmetic, and the page reports the largest gap that actually occurs on your band. For a 3:30:00 target the largest is 0.50 s, at the 22 km row. The finish row is printed with your target time exactly, with no rounding at all.

Why are all the splits the same?

Because the band is built on even splits — one pace, repeated — on the assumption that the course is flat and that you can hold a constant effort. That is a deliberate choice, not an oversight. A band carries one target time and one row per marker; a pacing model that moves the pace around needs assumptions about your course and your fitness that this page does not have and will not invent.

Does this replace a marathon pace chart?

It replaces the row of it you actually need. A marathon pace chart is a grid: distances down one side, a range of finish times across the top, and a pace in every cell. It is a reference document you look something up in. A band collapses that grid to your single target row and turns it into something you can wear, which is a different object for a different moment.

Can I get the band in miles?

Yes. Switch the unit control to Miles and the band carries 26 whole-mile rows plus the finish at 26.2188 mi. The marathon is 42.195 km by definition, which is 26.2187575 miles when converted at 1 mile = 1609.344 m; the 26.2188 printed on the band is that figure rounded to four decimals. The distance does not change, only the markers move.

Why does the band have a 50 mm line on it?

Because a pace band that prints at the wrong scale is not a pace band, it is a smaller or larger piece of paper with the same numbers on it. The band is drawn 170 mm wide and carries a line marked 50 mm. Print the page, hold a ruler against that line, and if it measures 50 mm your printer kept the page at 100%; if it does not, the print dialog scaled the page and the band is the wrong size.

Every split

Your printable pace band