Can a Half Marathon Qualify You for Boston?

Published October 9, 2026 · Estimates, updated each registration cycle

Short answer: no. The Boston Marathon only accepts a full marathon result as a qualifier. The time has to come from a 26.2 mile race on a certified course, run inside the qualifying window, and recorded as an official chip time. A half marathon, a 10K, a trail race or an ultra does not count, no matter how fast it was, and neither does a half run by the B.A.A. itself. Finishing the B.A.A.'s other races is fun, but it does not put you on the start line in Hopkinton. The rules behind this are explained in the certified course requirement.

That does not make the half useless. It is the single best tune up race for a Boston attempt, because it is long enough to test your aerobic engine and short enough that you recover in a week or two. Used well, a half tells you whether your marathon goal is realistic before you spend a whole build and a race entry on it.

Why Boston only takes the full distance

The qualifying standards exist to keep the field to runners who have proven they can cover the marathon distance at a given level. A half shows speed, but the last 10 kilometers of a marathon are a different test: fueling, pacing discipline and the ability to hold form when glycogen runs low. Plenty of runners have a half that predicts a comfortable qualifier and then fade badly after mile 20. The B.A.A. sidesteps that guesswork by asking for the real thing. On top of the standard, a yearly cutoff then trims the field. For Boston 2027 that cutoff was 5:17 under the standard, which is why the targets below include a buffer. If the cutoff idea is new to you, start with what a BQ actually is.

What half marathon time points to a safe BQ

The common way to convert a half into a marathon prediction is the Riegel formula, which says your marathon time is roughly 2.085 times your half time. Working backward from a marathon target gives the half you would need. The table uses the current standards and a planning buffer of 6:00, the same one used in what time you need for Boston 2028. Treat the half column as an estimate, not a promise.

Take a 45 year old woman. Her standard is 3:45:00, so with the planning buffer she aims for 3:39:00. Riegel says that matches a half of about 1:45:02. If she runs that half on a flat course in good conditions, her goal is in reach. If she runs a minute or two slower, the marathon target probably needs to move, or the build needs more time.

Why the estimate is often too kind

Riegel works best for runners who are already trained for the longer distance. Many amateurs race the half faster than their marathon fitness supports, because their long runs and weekly mileage are on the light side. In practice a lot of runners need a half a little quicker than the table shows to hit the marathon number. A useful rule: if your half came after a solid block of long runs at 18 to 22 miles, trust the estimate more. If it came off shorter training, add some margin. The habits that close that gap are covered in how to build a BQ buffer.

How to use a half in your Boston plan

Most coaches put a tune up half four to six weeks before the goal marathon. Race it hard, check the result against the table, then set your marathon pace from what you actually ran rather than what you hoped for. That one honest data point prevents the most common BQ mistake, which is going out at a pace your fitness cannot hold. Then plug your expected marathon time into the cutoff predictor to see how that buffer would have done against every real Boston cutoff since 2014.