Gun Time or Chip Time for a Boston Qualifier?

Published August 11, 2026 · Estimates, updated each registration cycle

Short answer: chip time. The Boston Athletic Association states that qualifying times are based on official submitted net time, also known as chip time, so the clock that matters is the one that started when you crossed the mat and stopped when you crossed the finish. If you lost ninety seconds shuffling from the third wave to the start line, those ninety seconds are not held against you.

Why the distinction exists at all

Gun time is measured from the starting horn for everyone in the field at once. Net time is measured per runner from the moment their timing chip crosses the start mat. At a small race with a single start the two are nearly identical. At a large city marathon with corrals and waves, the gap between them can run from a few seconds to several minutes depending on where you were seeded. Since Boston reads the net figure, a runner in the last corral is not penalized for the race organization putting them there.

What the BAA actually reads is the official result the qualifying race publishes and verifies. That is why the race matters as much as the number: the course has to be certified by USA Track and Field, AIMS, or the national governing body for the country where it is held. Our guide to the certified course requirement covers which races count and which do not.

Where chip time stops helping you

Three limits are worth knowing before you rely on it.

First, chip time only removes the walk to the start line. It does not remove congestion in the first three miles, and at a big race those crowded miles cost far more than the corral wait. If you are seeded honestly, the traffic is the real tax, not the clock.

Second, the time is taken as published, with no rounding in your favor. A finish of 3:00:00 against a 3:00:00 standard is a qualifier by exactly zero seconds, and 3:00:01 is not a qualifier at all. See does Boston round your qualifying time for how strictly that line is drawn.

Third, starting with the 2027 race, a verified time from a course with a net downhill of 1,500 feet or more gets a time adjustment added to it after submission: five minutes for drops of 1,500 to 2,999 feet and ten minutes for 3,000 to 5,999 feet. Your chip time is the input, but it is not necessarily the number the BAA ranks you on. The affected races are listed in our guide to which marathons are too downhill for Boston 2027.

What this changes about your target time

Practically, very little. You should already be aiming well under your age group standard, because meeting the standard only earns you the right to apply. The field is oversubscribed and fills from the largest margin downward, so the cutoff decides the rest. The 2026 race cut at 4:34 under the standard and our central estimate for 2027 is about 5:15, which is our own estimate and not a BAA figure. Against a buffer of that size, the difference between gun and net time is noise.

Use the chip time from your certified race, then run your age, gender and finish time through the cutoff predictor to see the buffer it gives you and whether that buffer would have been accepted in each of the last thirteen cycles. If you plan to submit in September, read the pre-verification guide first so nothing about your result stalls at review.