16 free calculators · no login · instant results

Swimming Calculator

Q: Can I use these calculators on my phone?

Yes. The site is mobile-first and responsive, working with touch inputs on any screen size.

Accurate, transparent tools for pace, time, distance, CSS, SWOLF, stroke efficiency, intervals, splits, calories, triathlon and open water swimming. Built for swimmers, coaches and triathletes.

Browse all calculators Calculate my pace

Free calculators

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m / yd

Full unit support

Most-used swimming calculators

Start with the tools swimmers and triathletes reach for every week. Every result includes a clear interpretation and links to related tools.

Swimming Pace Calculator

Work out your pace per 100 metres or yards from any distance and time. See speed and lap counts instantly.

Calculate my pace

CSS Calculator

Find your Critical Swim Speed from 200 m and 400 m efforts, plus training zones for threshold sets.

Calculate my CSS

Swimming Interval Calculator

Plan repeat distances, rest, send-offs and total set time. Perfect for building structured workouts.

Plan my intervals

Swimming Split Calculator

Break a target time into even splits for any distance, with cumulative times and a per-split pace.

Create training splits

SWOLF Calculator

Measure your swimming efficiency by combining time and stroke count. Track technique gains over time.

Check my SWOLF

Triathlon Swim Calculator

Estimate your triathlon swim time for Sprint, Olympic, Half-Iron and Ironman distances from your pace.

Estimate tri swim time

Every calculator, grouped by goal

Sixteen focused tools covering pace, time, distance, training, technique, units, triathlon and team calculations.

Pace & Speed

Pace Calculator

Time per 100 m or 100 yd from any distance and time.

Calculate pace

Speed Calculator

Distance per time in m/s, km/h and mph, plus pace.

Calculate speed

Time & Distance

Time Calculator

How long a target distance takes at a given pace.

Calculate swim time

Distance Calculator

How far you swim in a time at a known pace.

Calculate distance

Training & Intervals

CSS Calculator

Critical Swim Speed and training zones from 200/400 m.

Calculate CSS

Interval Calculator

Repeat times, rest, send-offs and total set duration.

Plan intervals

Split Calculator

Even and cumulative splits for any target time.

Create splits

Calorie Calculator

Energy burned by stroke, intensity and duration.

Estimate calories

Technique & Efficiency

SWOLF Calculator

Swimming efficiency from time plus stroke count.

Check SWOLF

Stroke Rate

Strokes per minute from stroke count and time.

Calculate stroke rate

Stroke Length

Distance per stroke and strokes per length.

Calculate stroke length

Pool & Unit Conversion

Pool Length Calculator

Total distance from lengths swum and pool size.

Calculate pool distance

Metres to Yards Converter

Convert m, yd, km and miles for swimming distances.

Convert distance

Triathlon & Open Water

Triathlon Swim

Estimate swim times for Sprint to Ironman.

Estimate tri time

Open Water Pace

Adjust pool pace for open water conditions.

Calculate open water pace

Relay & Team

Relay Calculator

Total relay time from up to four leg times and splits.

Calculate relay time

Accurate, transparent formulas

Every calculator shows the exact formula it uses. No black boxes — you can verify the maths on the formulas page.

Private by design

All calculations run in your browser. Nothing is sent to a server, no account is needed, and your inputs are never stored.

Built for every swimmer

From beginners tracking their first 400 m to coaches planning threshold sets and triathletes pacing an Ironman swim.

Learn the swimming maths

Formulas

Every equation behind the calculators, explained in plain English.

Units Guide

Metres, yards, laps and lengths — how swimming distances really work.

Glossary

Plain-English definitions of CSS, SWOLF, DPS, SPL and more.

Training Zones

How to train at the right intensity using your CSS and pace.

Frequently asked questions

Are these swimming calculators free to use?

Yes. Every calculator is completely free, with no login, no sign-up and no usage limits. All maths runs in your browser, so there are no API calls or server costs to pass on.

Do the calculators support both metres and yards?

Yes. Every distance-based tool lets you switch between metres and yards, and the unit converter handles metres, yards, kilometres and miles.

What is CSS and why should I calculate it?

CSS (Critical Swim Speed) is the fastest pace you can sustain without fatiguing quickly. It is calculated from two time trials — usually 200 m and 400 m — and gives you a reliable threshold pace for training sets. Use the CSS calculator to find yours.

Can I use these calculators on my phone?

Yes. The site is mobile-first and responsive. Every calculator works with touch inputs and adapts to any screen size from small phones to desktop monitors.

Are the formulas shown anywhere?

Yes — see the swimming formulas page for the full maths behind every calculator, including worked examples and the unit conversions used.

Ready to calculate your swim metrics?

Pick a tool, enter your numbers and get an instant, interpreted result. No accounts, no waiting.

Browse all 16 calculators