Race Cutoff Time Calculator

What does this calculator do?

The cutoff calculator answers one arithmetic question: if you hold an even pace from the start mat, plus the seconds it takes to reach that mat, do you still finish inside the course time limit? It also sketches four “checkpoint” rows at 25%, 50%, 75% and 100% of the distance.

Typical uses: checking a 6-hour marathon against 6:30/km, seeing how a wave start eats the buffer, and comparing your planned pace with the slowest pace that still hits the finish cutoff. It does not load Boston, Berlin or any other official gate table.

How does it work?

Distance comes from the same road presets as the pace calculator (marathon 42.195 km, half 21.0975 km). Estimated finish = start delay + planned pace × distance. Buffer = cutoff − estimated finish. The slowest allowed pace is cutoff ÷ distance (delay is not in that row: it is the pace that would consume the whole limit with zero delay).

Checkpoint “your split” = delay + pace × (distance × fraction). Checkpoint “cutoff reference” = cutoff × the same fraction. That is a straight line from 0 to the finish limit. Official manuals often place tighter early gates or use gun time at named km marks. Those published times replace this table.

The delay box is always added to your column. If the race enforces chip-time cutoffs, set delay to 0. If it enforces gun time, enter the expected seconds from the gun to the start mat. The page cannot know which clock a given race uses.

Formula

finish  = delay + pace(s/km) × distance(km)
buffer  = cutoff − finish
sweep   = cutoff / distance            // slowest even pace, no delay

checkpoint at fraction f (0.25, 0.5, 0.75, 1)
  yours   = delay + pace × distance × f
  cutoff* = cutoff × f                 // *linear sketch, not a race gate

Times round to the nearest second. The buffer row rounds to a whole minute; the green tip keeps one decimal. Distances in the table use one decimal (42.195 km appears as 42.2 km).

Worked example

How to interpret the result

Read “On track” as “an even 6:30 plus one minute of corral delay still fits a 6-hour finish cutoff.” It is not a promise you will be allowed past 30 km if that race’s real gate is tighter. A large buffer can vanish with walking, toilets and a late start.

Turn the planned pace into splits on the pace calculator or a printable pace band. Whether 6:30 is a realistic marathon from a recent 10K is a different model: the race time predictor.

Assumptions and limitations

Assumptions

• You hold the entered pace evenly from the start mat to the finish.
• The cutoff you type is the finish time limit on the clock the race actually uses.
• Start delay is seconds from that clock’s zero to when you start running (0 if chip-time).

Limitations

• The checkpoint table is a linear sketch of the finish cutoff. Official intermediate gates are often stricter and at named km marks.
• The page does not know gun versus chip. Wrong delay is a wrong comparison.
• No hills, weather, aid-station queues or negative-split model. Slowing down late is not shown.
• Sweep / min pace ignores delay. A long corral can put a “legal” pace over a gun-time cutoff.
• Missing a real gate usually means removal from the course. This page cannot list a race’s penalty.
• Cutoff outside 20 min–16 h, pace outside 2:30–30:00/km, or delay outside 0–3600 s is rejected. Walking paces are allowed.

Methodology and sources

Method type: Exact calculation

This is an exact definition: finish = delay + pace × distance, compared with the cutoff you enter. Distances use World Athletics road standards. The four checkpoint rows interpolate the finish cutoff; they are not copied from any race manual.

• Methodology: Course cutoffs
• Methodology: Pace, speed and distance
• Methodology: Rounding and displayed precision

Sources: NIST SP 811 · World Athletics Book of Rules

Last reviewed: October 5, 2026