How long does it take to recover from a half marathon?

About 8 days before a 10K at full effort and 9 days before another half marathon. Easy runs come back within a few days; racing all out takes longer.

How soon after a marathon can I race again?

A 10K at full effort from about 15 days, another marathon from 18 days, or 25 if it was your first marathon.

How long should you wait between two marathons?

If the second marathon is your goal race, leave at least 39 days (about 6 weeks): recovery from the first one plus a full taper. If the first is the goal race and the second is a B race, 18 days are enough to run it at full effort.

Should I run a half marathon before a marathon?

Yes, as a tune-up: at full effort 21 days or more before the marathon, controlled, without an all-out finish, from 15 days. Any closer, run it as training or skip it.

How long does it take to recover from a 50K or a 100-mile race?

After a mountain 50K, about 34 days before racing another one at full effort. After 100 mountain miles, about 53 days before a marathon and 61 days (about 9 weeks) before another 100.

How many marathons a year can I run?

Coaches usually advise two goal marathons a year. Spacing is the limit: a goal marathon needs 39 days after the previous race of the same length, plus weeks of its own build. B and C races fit in between at lower effort.

Race Recovery and Spacing Calculator

Set your goal race A, another race and the gap between them. The number is how ready you will be for the other race.

Goal race A

42.2km

Distance42.2km

Gain0m+

First time at this distance

Other race (B/C)

21.1km

Distance21.1km

Gain0m+

14 days before A

A42.2kmB/C21.1km

As training

14 days before A

full effort from 21 days

69%

First time at this distance

How it is calculated

Full recovery from a race grows with its flat distance and levels off: about 21 days after a marathon, 48 after 150 flat km, 58 after 250. The next race needs only part of it, see below. Anchors: Daniels, Pfitzinger, Foster and Higdon for road races; Dunstan, Howe and CTS for ultras; Hoffman 2016 for 100 miles.
The later race needs less freshness when it is short: a 10K forgives some fatigue, a 100 does not. A very short race needs 60% of full recovery, a marathon about 85%, a long ultra nearly all of it.
Before A, up to 21 days of taper are added in proportion to how long the other race is compared with A (Bosquet 2007 and Wang 2023 meta-analyses; Koop for ultras).
Before A the scale is stricter when the other race is over 85% of A or A is your first at the distance: a rehearsal that close eats the freshness (Sharp, McMillan, Torrence).
Racing the A distance for the first time stretches recovery 1.4 times. This is our inference from coaching practice (Fitzgerald, CTS), not a measurement.
Flat distance is distance plus 1 km per 100 m of gain (ITRA km-effort), with a small allowance for trail terrain. It is rougher than our FlatKM model, which reads the course itself.

Recovery and race spacing: short answers

How long does it take to recover from a half marathon?: About 8 days before a 10K at full effort and 9 days before another half marathon. Easy runs come back within a few days; racing all out takes longer.
How soon after a marathon can I race again?: A 10K at full effort from about 15 days, another marathon from 18 days, or 25 if it was your first marathon.
How long should you wait between two marathons?: If the second marathon is your goal race, leave at least 39 days (about 6 weeks): recovery from the first one plus a full taper. If the first is the goal race and the second is a B race, 18 days are enough to run it at full effort.
Should I run a half marathon before a marathon?: Yes, as a tune-up: at full effort 21 days or more before the marathon, controlled, without an all-out finish, from 15 days. Any closer, run it as training or skip it.
How long does it take to recover from a 50K or a 100-mile race?: After a mountain 50K, about 34 days before racing another one at full effort. After 100 mountain miles, about 53 days before a marathon and 61 days (about 9 weeks) before another 100.
How many marathons a year can I run?: Coaches usually advise two goal marathons a year. Spacing is the limit: a goal marathon needs 39 days after the previous race of the same length, plus weeks of its own build. B and C races fit in between at lower effort.

Free tools

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Race Recovery and Spacing Calculator

Set your goal race A, another race and the gap between them. The number is how ready you will be for the other race.

Goal race A

42.2km

Distance42.2km

Gain0m+

First time at this distance

Other race (B/C)

21.1km

Distance21.1km

Gain0m+

14 days before A

A42.2kmB/C21.1km

As training

14 days before A

full effort from 21 days

69%

First time at this distance

How it is calculated

Full recovery from a race grows with its flat distance and levels off: about 21 days after a marathon, 48 after 150 flat km, 58 after 250. The next race needs only part of it, see below. Anchors: Daniels, Pfitzinger, Foster and Higdon for road races; Dunstan, Howe and CTS for ultras; Hoffman 2016 for 100 miles.
The later race needs less freshness when it is short: a 10K forgives some fatigue, a 100 does not. A very short race needs 60% of full recovery, a marathon about 85%, a long ultra nearly all of it.
Before A, up to 21 days of taper are added in proportion to how long the other race is compared with A (Bosquet 2007 and Wang 2023 meta-analyses; Koop for ultras).
Before A the scale is stricter when the other race is over 85% of A or A is your first at the distance: a rehearsal that close eats the freshness (Sharp, McMillan, Torrence).
Racing the A distance for the first time stretches recovery 1.4 times. This is our inference from coaching practice (Fitzgerald, CTS), not a measurement.
Flat distance is distance plus 1 km per 100 m of gain (ITRA km-effort), with a small allowance for trail terrain. It is rougher than our FlatKM model, which reads the course itself.

Recovery and race spacing: short answers

How long does it take to recover from a half marathon?: About 8 days before a 10K at full effort and 9 days before another half marathon. Easy runs come back within a few days; racing all out takes longer.
How soon after a marathon can I race again?: A 10K at full effort from about 15 days, another marathon from 18 days, or 25 if it was your first marathon.
How long should you wait between two marathons?: If the second marathon is your goal race, leave at least 39 days (about 6 weeks): recovery from the first one plus a full taper. If the first is the goal race and the second is a B race, 18 days are enough to run it at full effort.
Should I run a half marathon before a marathon?: Yes, as a tune-up: at full effort 21 days or more before the marathon, controlled, without an all-out finish, from 15 days. Any closer, run it as training or skip it.
How long does it take to recover from a 50K or a 100-mile race?: After a mountain 50K, about 34 days before racing another one at full effort. After 100 mountain miles, about 53 days before a marathon and 61 days (about 9 weeks) before another 100.
How many marathons a year can I run?: Coaches usually advise two goal marathons a year. Spacing is the limit: a goal marathon needs 39 days after the previous race of the same length, plus weeks of its own build. B and C races fit in between at lower effort.