Track interval & split calculator

Worked example: three 400-meter repeats

At 4:00/km, each 400 m repeat takes 96 seconds, or 1:36. With 1:00 recovery between three repetitions, start at 0:00, 2:36 and 5:12; finish at 6:48. The session contains 4:48 of work and 2:00 of recovery. There is no recovery after the last repeat.

Lap checkpoints and session clocks

Within-repeat checkpoints restart from zero for each repetition. Session start and end columns include earlier work and recoveries. Repeat time = pace in seconds per meter × repeat distance. Session time = number of repeats × repeat time + (number of repeats − 1) × recovery.

Enter the measured length of the loop you use: 400 m for a standard lap, 200 m for a shorter track, or a custom value. The calculator divides each repeat into full loops plus a partial distance. It does not infer outer-lane distance or staggered starting positions. A mile is exactly 1,609.344 m, so four 400 m laps are 9.344 m short of a mile; see the NIST conversion reference.

Scope and output

Choose your own target pace; equivalent times at other distances assume that same constant speed and are not fitness predictions. The plan supports 1–100 repeats, 10–10,000 m per repeat, a measured lap length of 10–2,000 m, and at most seven days of session time. Recovery can be 0:00. Recovery distance, warm-up and cooldown are excluded from the work distance.

Copy, CSV and print include the repetition schedule; the CSV also includes within-repeat checkpoints. Displayed times round to tenths, while exported calculation rows retain full numeric precision. For a continuous race, use the race split calculator. For timed walking breaks, use the run/walk finish-time calculator.