Modern swim watches track a lot of numbers. Most swimmers glance at them and move on without really knowing what they mean. Here’s a clear guide to the metrics that actually matter.
Pace Per 100m (or 100 yards)
What it is: The time it takes you to swim 100 meters at your current effort level.
Why it matters: This is your primary training metric — the equivalent of pace per mile for runners. Use it to set interval targets, track fitness over time, and evaluate effort.
Good to know: Your pace varies significantly by stroke and effort level. Establish separate baselines for freestyle easy, freestyle hard, and any other stroke you train.
SWOLF
What it is: Stroke count + time for one pool length. Stands for “swim golf” — like golf, lower is better.
Why it matters: SWOLF measures efficiency, not just speed. A lower SWOLF means you’re covering distance with less energy.
Good to know: Only compare SWOLF scores within the same stroke and pool length. A 25m pool SWOLF and a 50m pool SWOLF are not comparable.
Stroke Rate (Strokes Per Minute)
What it is: How many strokes you take per minute. One stroke = one arm cycle (both arms).
Why it matters: Stroke rate, combined with distance per stroke, determines your speed. Most recreational swimmers have a stroke rate that’s either too low (they’re gliding inefficiently) or too high (they’re spinning without much propulsion).
Good to know: Elite freestylers at top speed have stroke rates of 50–60 strokes/minute. Recreational swimmers at easy effort are typically in the 30–45 range.
Distance Per Stroke (DPS)
What it is: How far you travel per stroke cycle.
Why it matters: DPS measures how effectively each stroke propels you forward. More distance per stroke means less wasted energy.
Good to know: DPS and stroke rate have an inverse relationship — as you stroke faster, DPS typically decreases. The goal is finding the combination that maximizes speed without sacrificing too much efficiency.
Stroke Count Per Length
What it is: The number of strokes to complete one pool length.
Why it matters: A quick, trackable proxy for efficiency. If your stroke count per 25m is typically 18 and it climbs to 24 mid-set, your stroke is breaking down.
Good to know: Your optimal stroke count will change as you improve. Track it directionally, not as an absolute target.
Heart Rate
What it is: Beats per minute during your swim.
Why it matters: Optical heart rate sensors on smartwatches are less accurate in water (water movement disrupts the sensor). For precise HR data in the pool, a chest strap (Polar, Garmin) worn under a wetsuit or swimskin is more reliable.
Good to know: Even imperfect HR data can show you broad training zones — useful for distinguishing easy vs. threshold vs. hard efforts.
How to Use These Together
Don’t try to optimize all metrics at once. Pick one:
- Want more speed? Focus on pace per 100m trend over time.
- Want better efficiency? Track SWOLF and aim to lower it while maintaining pace.
- Working on stroke technique? Monitor stroke count per length during drill sets.
One metric, consistently tracked over weeks, tells you more than five metrics tracked sporadically.