Swimming Efficiency Test: Strokes Per 100m and the SWOLF Metric

Introduction

In swim training, “swimming fast” is the most intuitive goal, but “swimming efficiently” is the real foundation for long-term improvement. A swimmer with very few strokes but very slow speed, and a swimmer with an extremely high stroke rate but very little distance covered per stroke, are both far from ideal. So how do you measure speed and efficiency at the same time?

SWOLF (short for Swimming + GOLF, borrowing golf’s “lower score wins” logic) offers a simple yet powerful answer. SWOLF combines time (speed) and stroke count (efficiency) into a single number, making it one of the most widely used swimming efficiency metrics today. Many smart swim watches (such as Garmin and Apple Watch) have built-in SWOLF calculation.

How SWOLF Is Calculated

The SWOLF formula is very simple:

SWOLF = time for one length (usually 25m or 50m) in seconds + number of strokes for that length

For example:

Swimmer	25m Time (sec)	Stroke Count	SWOLF
A	30	20	50
B	25	30	55
C	22	18	40
D	35	10	45

Swimmer C has the lowest SWOLF (40), meaning they achieve a relatively fast speed with the fewest strokes — the highest efficiency. Swimmer A takes fewer strokes but swims slowly, so overall efficiency is lower than C’s. Swimmer D takes the fewest strokes of all, but is extremely slow, which is also not ideal.

Strokes Per 100m

Besides SWOLF, “strokes per 100m” is another common efficiency metric. It is calculated by recording the total number of strokes taken over 100 meters.

Reference ranges by skill level (freestyle, 25m pool):

• Beginner: about 25–35 strokes per 25m
• Advanced amateur: about 18–25 strokes per 25m
• Competitive level: about 14–20 strokes per 25m
• Elite swimmers: about 10–16 strokes per 25m (including the advantage of the push-off glide)

Note that fewer strokes is not always better — the goal is to minimize stroke count while maintaining a reasonable speed. An extremely low stroke count paired with an extremely slow speed may cover a long distance per stroke, but this “gliding” style can actually be less effective for aerobic endurance than a more moderate rhythm.

Distance Per Stroke (DPS)

Another related metric is DPS (Distance Per Stroke), which calculates the average distance covered per stroke:

DPS = pool length ÷ number of strokes

For example, taking 20 strokes in a 25m pool gives DPS = 25 ÷ 20 = 1.25 meters per stroke.

DPS is a direct indicator of technical improvement. As your entry point improves and your high-elbow catch technique strengthens, the distance covered per stroke should gradually increase. It is recommended to record your stroke count over a fixed distance (such as 50m) once a month to track long-term trends in DPS.

Applying SWOLF in Training

Application 1: Efficiency Monitoring in Technique Sets
In technique-focused training sets, ask swimmers to minimize SWOLF while maintaining a certain speed. This prevents swimmers from simply increasing stroke rate to go faster, and instead pushes them toward technical improvements that cover more distance per stroke.

Application 2: A Pacing Tool for Aerobic Training
In aerobic endurance training, requiring a consistent SWOLF value (rather than a consistent time) better ensures reasonable pacing and consistent stroke quality.

Application 3: Fatigue Monitoring
In the later stages of a workout (for example, the final sets after 3000m), a noticeable rise in SWOLF indicates that fatigue is causing technique to break down — a signal that appropriate rest is needed.

Practical Tips

• During the warm-up set of each swim session, count your strokes over 25m to record your baseline efficiency for the day.
• Set up a monthly “SWOLF test day”: swim a timed 400m, counting strokes for each 25m length, and calculate your average SWOLF to track monthly progress.
• Stroke count training (Count Training): set a target stroke count (for example, no more than 22 strokes per 25m) and try to swim as fast as possible within that limit — an effective way to improve DPS.
• If you use a swim watch that supports SWOLF, you can set a target SWOLF value so the watch gives you real-time pacing alerts.

Conclusion

SWOLF and stroke-count metrics provide an objective, quantifiable basis for tracking swimming progress, turning the question “has my technique improved?” into something measurable. In Taiwan’s swimming environment, these free and easy-to-record metrics can be tracked entirely on your own, with no high-tech equipment required. Starting to count your strokes today is the simplest first step toward systematic swim training.

Related Reading

• 游泳效率指標 SWOLF：計算方式與改善策略
• SWOLF 指標完全解讀：用一個數字優化游泳技術
• 游泳訓練數據化：SWOLF、CSS與訓練壓力分數的完整計算指南
• 游泳划頻與划距：SWOLF 與效率優化，教練帶你把每一趟都游得更聰明