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Swim Pace Calculator

Computes swimming pace per 100 metres and per 100 yards, speed in m/s and km/h, and the number of 25 m and 50 m pool lengths from a swum distance and time.

When to use

You swam (or plan to swim) a given distance in a given time and need the pace per 100 m or 100 yd, e.g. to set interval targets.

Do not use when: The distance is in yards (convert first: 1 yd = 0.9144 m) or you need running/cycling pace (use running-pace or pace-converter).

Formula

pace_100m = time_seconds × 100 / distance_m; pace_100yd = pace_100m × 0.9144; speed_m_per_s = distance_m / time_seconds; speed_kmh = speed_m_per_s × 3.6

Inputs

Parameter	Type	Unit	Required	Description
`distance_m`	number	m	yes	Distance swum in metres. Range: > 0, ≤ 100000
`time`	string		yes	Elapsed time as h:mm:ss, mm:ss (30:00) or plain minutes.

Outputs

Output	Type	Unit	Description
`pace_per_100m`	string	min:sec/100 m	Time per 100 metres.
`pace_per_100yd`	string	min:sec/100 yd	Time per 100 yards (91.44 m).
`pace_seconds_per_100m`	number	s/100 m	Same pace as seconds per 100 m.
`speed_m_per_s`	number	m/s	Average speed in metres per second.
`speed_kmh`	number	km/h	Average speed in kilometres per hour.
`lengths_25m_pool`	number	lengths	distance_m / 25.
`lengths_50m_pool`	number	lengths	distance_m / 50.

Example

1500 m in 30:00: {"distance_m":1500,"time":"30:00"} → {"pace_per_100m":"2:00","pace_per_100yd":"1:50","pace_seconds_per_100m":120,"speed_m_per_s":0.833,"speed_kmh":3,"lengths_25m_pool":60}

400 m in 6:40: {"distance_m":400,"time":"6:40"} → {"pace_per_100m":"1:40","pace_per_100yd":"1:31","speed_m_per_s":1,"speed_kmh":3.6,"lengths_50m_pool":8}

GET https://tttkmbb.com/api/v1/calculate/swim-pace?distance_m=1500&time=30%3A00

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/swim-pace (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/swim-pace · Markdown: https://tttkmbb.com/fitness/swim-pace.md · JSON definition: https://tttkmbb.com/fitness/swim-pace.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="swim-pace"
OpenAPI operationId: calculate_swim_pace
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

FAQ

Why is the pace per 100 yards faster than per 100 metres?

100 yards is 91.44 m, about 8.6 % shorter, so the same speed gives a proportionally shorter time. Short-course-yards (SCY) times are not directly comparable with metres.

What is a typical pace?

Recreational lap swimmers commonly hold 2:00–2:30 per 100 m; competitive distance swimmers are near 1:05–1:15 per 100 m.

Related calculators

Pace Converter — Convert running paces and speeds between units.
Calories Burned Calculator — Energy cost of the swim from its duration.