Cutoff Pace Calculator

What this page does

A cutoff pace calculator starts from a clock you are not allowed to miss. Give it a distance and a time limit and it returns the slowest average pace that still gets you to the line inside that limit — per kilometre and per mile, with the speed in both units and the clock a 5 km block and a 5 mile block would take. Add the checkpoint clocks a race hands out and the same limit splits into the stretches that end at those points, each with its own required pace. Then type your own clock at the finish or at a checkpoint and the page reads the margin against that cutoff and spreads it over the distance, in seconds per kilometre.

The race pace calculator answers the neighbouring question: it converts between distance, finish time and pace for a race you are planning, in whichever direction you have the numbers. It knows nothing about a clock you have to beat at a point on the course, and it has no checkpoint list. The split pages — the marathon split calculator and the mile splits calculator — draw kilometre or mile clocks from a pace you have already chosen. This page is the cutoff side of the same arithmetic, and the checkpoint table and the margin are the two parts neither of them has.

The division itself, a clock divided by a distance, is the division every pace page on this site does. What is different here is what goes into it: a limit you must not exceed and the clocks that come with it, rather than a target you picked. No number on this page is transcribed from a race.

Everything runs in your browser. Nothing you type is sent to a server, there is no account and no upload, and the numbers never leave the page.

How the numbers are calculated

Three definitions carry the whole page and all three are exact: 1 km = 1000 m; 1 mile = 1609.344 m, the international mile fixed by the 1959 yard and pound agreement; 1 hour = 3600 s. From those, a time limit T in seconds over a distance D in metres gives a pace in seconds per metre, and the two printed paces are that pace scaled to the two units:

p = T ÷ D    p_km = 1000 × p    p_mi = 1609.344 × p

Speed is the same quantity inverted, in metres per second, printed in km/h and mph. A block of 5 km costs 5000 × p seconds and a block of 5 miles costs 5 × 1609.344 × p; those are the two block figures in the stats row.

Checkpoints: the same limit, cut into stretches

A checkpoint is a distance D_i and a clock T_i measured from the gun. Each stretch between two consecutive points has its own pace, and it is that stretch's clock divided by that stretch's length:

p_i = (T_i − T_i−1) ÷ (D_i − D_i−1)

with T₀ = 0 and D₀ = 0 at the start and the last point the finish. Those stretch paces need not equal the overall cutoff pace, and usually do not: a limit that is generous early and tight late produces a fast last stretch, and the overall figure hides it.

The margin, and what it is worth per kilometre

The margin at a point is the cutoff clock there minus your own clock there. Divided by the distance it has to cover, it becomes seconds per unit of distance:

m = T_i − t_i    margin per km = m ÷ (distance ÷ 1000)

At the finish, the distance the margin is spread over is the whole course, because that is where it was accumulated. At a checkpoint it is the distance still to run, because that is what the margin has to pay for. The sentence the page prints says which of the two it used.

A worked example: 42.195 km in 6:00:00

21,600 seconds over 42.195 km is 0.511909 seconds per metre, printed 8:32 per kilometre and 13:44 per mile, which is 7.03 km/h. A 5 km block costs 2,559.5 seconds, printed 42:40, and a 5 mile block costs 4,119.2 seconds, printed 1:08:39.

Now add two checkpoints: 1:30:00 at 10 km and 3:00:00 at the half. The first stretch is 10 km in 1:30:00, which is 9:00 per kilometre. The second is 11.0975 km in 1:30:00, which is 8:07. The third is 21.0975 km in 3:00:00, which is 8:32. The overall 8:32 was true of the whole course and true of neither of the first two stretches.

The margin: if your clock at the half is 2:50:00 against a 3:00:00 checkpoint, you are 10:00 inside it, and 600 seconds over the 21.0975 km left is 28.4 s per kilometre of room. The time limit still leaves 3:10:00 for that 21.0975 km, which is 9:00 per kilometre.

• T — the time limit in seconds, written hh:mm:ss or mm:ss. 1:00 to 47:59:59.
• D — the measured length the limit applies to, in metres. 100 m to 200 km.
• p_km, p_mi — the cutoff pace in seconds per kilometre and per mile.
• T_i, D_i — a checkpoint's clock and distance. Up to three, each strictly later and further along than the one before.
• m — the margin in seconds: positive inside the cutoff, negative behind it.

The checkpoint clocks, and the pace between them

Most races publish a clock at the finish and, less often, a second clock at a point on the course: a halfway cutoff, a bridge, the place where the course leaves a park. A checkpoint is not a second race. It is the same limit measured twice, and the two measurements do not have to imply the same pace.

The table on this page takes up to three of them. Each row is one stretch: the distance at its end, the length of the stretch, the clock you must be at that point by, and the pace that stretch demands in both units. The row that asks for the fastest average is highlighted. Leave the boxes empty and the table collapses to a single row, which is the whole course.

Two things follow from the arithmetic and are worth saying plainly. The stretch paces and the overall pace are different numbers, so a plan built on the overall figure alone will be wrong on at least one stretch. And a stretch pace is a floor for that stretch, not a target: an even pace and an even effort are different plans once the floors differ, and this page does not choose between them.

None of these numbers come from a race. The page holds no cutoff table, no course and no checkpoint list; every distance and clock in the table is one you typed.

Reading a cutoff that is given in miles

Some races publish the limit in miles, and some runners think in miles whatever the race publishes. Change the distance unit to miles and every distance box on the page, including the three checkpoint boxes, is read in miles. Nothing else changes.

A 26.2 mile limit of 6:00:00 is 13:44 per mile and 8:32 per kilometre. Three more, at the distances people type in miles:

The mile pace is the limit divided by the miles, and the kilometre pace is the same limit divided by the same distance expressed in kilometres, so the two columns are one conversion apart: 1.609344 kilometres to the mile.

Supported range and limits

• Distance: 100 m to 200 km, typed in km, miles or metres. 200 km is 124.27 miles.
• Time limit: 1:00 to 47:59:59, written hh:mm:ss or mm:ss. A number with no colon is refused, because 6 could mean six minutes or six hours.
• Checkpoints: up to three, each strictly further along and strictly later than the one before it, all inside the course and all before the time limit.
• Rounding: paces to the nearest second, distances to three decimals, margins to a tenth of a second. One rounding, at the end, never halfway through a chain.
• 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 race's cut-off table. The page holds no published cutoff for any race, in any year, at any distance. A real cutoff belongs to one race's own rules for one edition, and races change both the clocks and the points. The boxes are yours to fill, and nothing here is transcribed.
• No course presets and no checkpoint list. There is no “Boston” or “Berlin” option and no halfway marker built in. A preset would mean shipping one course's layout, and courses are re-measured.
• No prediction. The page converts a clock you give it into a pace. Whether you can hold that pace is not in the arithmetic and is not something this page can know.
• No training plan. No weekly volume, no session, no target for next week. It is a calculator, not a coach.
• No weather or grade correction. Heat, wind, humidity and a hilly course all move what a given pace costs, and none of them is priced here. Elevation is a page of its own: the altitude pace calculator takes an altitude and returns the sea-level equivalent.
• No verdict on whether the pace is hard for you. Nothing here says a cutoff pace is comfortable, tough, fast or slow. That would need your own fitness and a set of cut-points, and the page has neither.
• No split table and no printable band. The page never draws a kilometre-by-kilometre or mile-by-mile clock. The marathon split calculator, the mile splits calculator and the marathon pace band do that, from a pace you choose.
• No accounts, no saved history, no bulk mode. One limit, one course, up to three checkpoints on it, one answer. Nothing is stored, so reloading the page clears it.

Questions

How do I work out the pace I need to beat a cut-off time?

Divide the time limit by the distance. A 6:00:00 limit over 42.195 km is 21,600 seconds divided by 42.195 km, which is 511.9 seconds per kilometre, printed 8:32 per km and 13:44 per mile. That is the slowest average that still gets you to the finish inside the limit, so every kilometre has to average 8:32 or better. Type the two numbers into the boxes at the top of this page and it does the same division.

What is a cutoff pace?

It is the average pace implied by a time limit. Races publish a clock rather than a pace, because the clock is what they enforce, but the clock and the distance together fix a pace: the limit divided by the distance. On this page the cutoff pace is that one number, per kilometre and per mile, and everything else here is built from it. It is a floor, not a target: any average slower than it misses the clock.

What does a six-hour marathon cutoff work out to per kilometre?

8:32 per kilometre, or 13:44 per mile. The arithmetic is 21,600 seconds over 42.195 km for the pace per kilometre, and 21,600 seconds over 26.21875 miles for the pace per mile. The same clock over the half marathon distance, 21.0975 km, is also 8:32 per kilometre, because both the distance and the clock are exactly halved. This page prints both units for whatever distance and clock you type.

How do I convert a cutoff pace to minutes per mile?

Multiply the pace per kilometre by 1.609344, which is the number of kilometres in a mile. A cutoff pace of 8:32 per kilometre is 511.9 seconds per kilometre, and 511.9 times 1.609344 is 823.8 seconds per mile, printed 13:44. The page does it in the other direction too: type the distance in miles and the mile pace comes out directly, with no conversion step for you to do.

What is a checkpoint cutoff, and how is its pace different?

A checkpoint cutoff is a clock at a point before the finish, and the pace it implies covers only the stretch that ends there. If a race gives you 1:30:00 at 10 km and 3:00:00 at the half, the second stretch is 11.0975 km in 1:30:00, which is 8:07 per kilometre, while the whole course at 6:00:00 averages 8:32. The middle stretch is faster than the overall average because the first stretch was slower. Fill in the checkpoint boxes and the table on this page prints each stretch on its own.

Can I enter a cutoff that is given in miles?

Yes. Change the distance unit to miles and every distance box on the page, including the checkpoint boxes, is read in miles. A 26.2 mile limit of 6:00:00 returns 13:44 per mile and 8:32 per kilometre. The page prints the pace per kilometre and per mile side by side whichever unit you typed, so you do not have to convert anything yourself.

How much room do I have if I am ahead of the cutoff at a checkpoint?

The margin is the checkpoint clock minus your own clock at that point, and dividing it by the distance still to run turns it into seconds per kilometre. Ten minutes ahead at the half of a marathon leaves 21.0975 km to run, so the margin is worth 28.4 seconds per kilometre of room, or 45.8 seconds per mile. Type your clock at the point in the box below the table and the page prints both figures, plus the pace the remaining time limit leaves you.

Does this page list any race's actual cut-off times?

No. It holds no race's clock, no course's checkpoint list and no start-corral layout. Every number it works with is one you typed: the distance, the time limit and, if you have them, the checkpoint clocks for the race you are running. A table of real cut-off times would need one race's own published data for one year, and races change both the clocks and the points, so the boxes stay yours to fill.