swim

Swim faster. Train smarter.

Free swimming calculators based on Swim Smooth methodology and World Aquatics standards. No account needed.

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Tools

Live
Swim Pace Calculator
Convert between pace per 100m, per 100 yards, and speed in km/h or mph. Works for pool and open water.
per 100mper 100ydkm/htriathlon
Live
Critical Swim Speed (CSS)
Find your CSS threshold pace from a 400m and 200m time trial. The swimming equivalent of FTP.
threshold pacetraining zones400m + 200m
Live
Swim Training Zones
Calculate your 5 training zones from your CSS pace. Zone 1 recovery to Zone 5 sprint pace ranges per 100m.
5 zonesCSS-basedSwim Smooth/100m
Live
SWOLF Score
Calculate your SWOLF efficiency score from stroke count and lap time. Lower is better.
strokes + timeefficiency25m / 50m
Live
Open Water Pace Calculator
Calculate open water swim time accounting for wetsuit advantage, currents, sighting, and chop. Plan your triathlon swim or open water race.
wetsuitsightingcurrenttriathlon

Frequently asked questions

What swimming calculators are available on dincalculator.com?

Five. A swim pace calculator for converting between per 100m, per 100yd and speed in km/h or mph; a Critical Swim Speed (CSS) calculator for finding your aerobic threshold pace from time trials; a SWOLF score calculator for measuring efficiency from stroke count and lap time; a training zones calculator; and an open water pace tool.

What is Critical Swim Speed (CSS)?

Critical Swim Speed (CSS) is the fastest pace a swimmer can sustain over a long distance without accumulating significant fatigue. It is calculated from a 400m and a 200m time trial and represents the aerobic threshold in swimming, the equivalent of FTP in cycling or lactate threshold pace in running.

What is SWOLF in swimming?

SWOLF is a measure of swimming efficiency calculated by adding the number of strokes per length to the time in seconds for that length. For example, 18 strokes plus 45 seconds is a SWOLF of 63. A lower SWOLF score indicates better technique and efficiency. It is used by Garmin, Apple Watch and Polar devices to track swimming performance.

Are these swimming calculators free?

Yes. All swimming calculators on dincalculator.com are completely free to use with no account, registration, or subscription required.