Use this simple calculator to calculate your Swim Threshold and estimate your ideal swim pace training zones in meters or yards.

Your Swim Threshold test is a simple way to measure your swim fitness. It estimates the pace per 100 that you would maintain 1 hour without going anaerobic.

To test Swim a maximal 400 and 200 time trial within the same session, with a five-minute active recovery between, and time yourself for both. Enter your 400 and 200 times below.

After calculating your Swimming Pace Zones, you can also print your results or download as a PDF below.

Step 1.    Calculate My Swim Critical Speed

Error: Your 200 pace is slower than your 400 pace! It is not possible to have a 200 pace slower than your 400 pace because you must have swam a quicker 200 within the 400. Remember the 200 and 400 times should be well paced timetrial results - if these are your real times then we're sure you can swim a faster 200. Is it possible you started too fast and blew up?

Step 2.  Calculate My Swim Speed Training Zones
Swim Speed Training Zones Feel Swim Speed (mm:ss / 100 meters or yards)
1 Easy / Recovery
2 Endurance
3 Moderate
4 Threshold
5 Vo2 Max