Stroke length calculator
Distance, time and a stroke count in; stroke length, stroke rate, speed and SWOLF out. The start and breakout come off the distance first, so the stroke length is the swimmer's and not the dive's.
Results
- Stroke length distance per stroke
- 2.29m per cycle
- Stroke rate
- 52.5cycles/minover the clean section
- Velocity
- 2.00m/sclean swimming, 0:50.0 per 100 m
- SWOLF
- 17.9per length10.9 s + 7 cycles24.9 counting every hand entry
How these were worked out
- Clean distance: 25 m − 9 m = 16 m
- Stroke length: 16 m ÷ 7 cycles = 2.29 m per cycle
- Stroke rate: 7 cycles ÷ 8.0 s × 60 = 52.5 cycles/min
- Velocity: 16 m ÷ 8.0 s = 2.00 m/s
- SWOLF: 10.9 s + 7 cycles = 17.9
What the calculator works out
- Stroke length
Stroke length = (distance − start and breakout) ÷ cycles
Also called distance per stroke, or DPS: how far the swimmer travels in one stroke cycle, in metres per cycle. Only the distance swum with strokes counts.
- Stroke rate
Stroke rate = cycles ÷ clean time in seconds × 60
How many cycles the swimmer takes per minute, over the same clean section the stroke length comes from.
- Velocity
Velocity = stroke length × stroke rate ÷ 60
Speed over the clean section, in metres per second. Because velocity is the product of the other two, measured numbers have to agree; when they don't, one of them was taken over a different stretch of water.
- SWOLF
SWOLF = seconds for one length + cycles for that length
Short for swim golf, and as in golf, lower is better: fewer strokes, less time, or both, for the same length. Unlike the other three it covers the whole length, push-off included, because that is how it is defined. Compare it with the swimmer's own earlier scores, not with anyone else's.
Two things to get right before you enter anything
- Count cycles, not hand entries. In freestyle and backstroke one cycle is a left and a right arm, so 14 hand entries are 7 cycles. Counting entries halves the stroke length and doubles the stroke rate. If that is how you counted, choose "Arm strokes" and the calculator converts.
- Leave the start and breakout out. A dive and underwater phase can cover 10 to 15 m of a 25 m length without a stroke. Divide the whole length by the cycles and all of it is credited to the stroke. Enter the distance before the first stroke and it is subtracted.
Why both matter, and what to do with the number afterwards, is in How to calculate stroke length in swimming.
Worked example: a 100 m training repeat
A swimmer does a 100 m freestyle repeat in a 25 m pool in 1:20.0 and takes 80 hand entries, which is 40 cycles. They break out at about 5 m off each of the four walls, so 20 m are excluded.
- Clean distance: 100 m − 20 m = 80 m
- Stroke length: 80 m ÷ 40 cycles = 2.00 m per cycle
- SWOLF: (80 s + 40 cycles) ÷ 4 lengths = 30 per length, or 40 counting every hand entry
- Velocity: 100 m ÷ 80 s = 1.25 m/s, which is 1:20.0 per 100 m
- Stroke rate, estimated: 80 s × 80 ÷ 100 = 64 s of clean swimming, and 40 cycles ÷ 64 s × 60 = 37.5 cycles/min
There is no separate time for the 80 clean metres, so the calculator assumes the push-offs went at swimming speed. That is close enough to compare one repeat with the next. On a dive length it reads high, because a dive travels faster than any stroke, which is why the race example the calculator opens with times the clean section from breakout to wall.
Skip the stopwatch
Counting strokes and splitting a watch at the breakout is fiddly with a full lane. Swim Analyzer Pro takes the same measurements from a phone clip: it finds the pool walls and the breakout in the footage, so the clean section is the same section every time, and stroke length, stroke rate and velocity come from one measurement.
Measure it automatically from video →Questions
How do I calculate stroke rate in swimming?
Count the stroke cycles over a timed section of clean swimming, divide by the time in seconds and multiply by 60: 7 cycles in 8.0 seconds is 52.5 cycles per minute. On deck it is quicker to time three cycles and divide 180 by that time, so three cycles in 3.4 seconds is 52.9 cycles per minute.
What is a good SWOLF score?
There is no universal one. SWOLF depends on the pool length, the stroke, the swimmer's height and whether strokes are counted as cycles or as single arm strokes, so a score only compares with the same swimmer's scores under the same conditions. Use it between repeats: a lower score at the same pace means the swimmer covered the length with fewer strokes.
Should I count arm strokes or full cycles?
Cycles. Stroke length and stroke rate are reported per cycle in coaching and research, so a number counted in arm strokes cannot be compared with them. If you have already counted every hand entry, choose "Arm strokes" and the calculator halves the count.
Why is my stroke rate marked as estimated?
Without a time for the clean section, the calculator assumes the start and breakout were covered at the same speed as the swimming. That is close for push-offs in training and reads high on a dive length, because a dive is faster than swimming. Enter the time from breakout to finish for an exact figure.
Does the calculator work in yards?
Yes. Choose the 25 yd pool and enter the distances in yards: stroke length comes out in yards per cycle and velocity in yards per second. Stroke rate and SWOLF do not depend on the unit.