How much should my child’s swim times improve each year?

Based on more than 680,000 Australian race results (2022–2026), the median year-on-year improvement is about 12% at age 8–9, around 8–10% through ages 9–11, 4–7% at 11–13, and under 3% from age 14 onwards. There is wide variation around these medians, so slower years are normal.

Is it normal for a teenage swimmer to plateau?

Yes. By ages 15–16 the median improvement is about 1.5% per year, and a rising share of swimmers do not beat a given event in a given year. Smaller gains at this age reflect maturation, not lack of effort, and are consistent with published research on adolescent swimming performance.

Which stroke improves fastest in young swimmers?

Butterfly. Across ages 9–14 in the Australian data, butterfly shows the largest median year-on-year improvement (about 7.1%) and freestyle the smallest (about 5.8%). A likely reason is that the more technical strokes leave more room to improve.

Australian data · 2022–2026

How much do age-group swimmers improve each year?

Q: Do boys and girls improve at the same rate?

They are the same until about age 11, then diverge. By ages 13–14 the median girl improves about half as fast as the median boy, and by 16 girls are close to steady while boys still gain about 1% a year. This lines up with girls reaching their adolescent growth spurt earlier, and there is wide individual variation.

Median year-on-year improvement from more than 680,000 Australian race results: about 10% at age 9–10, easing to about 1.5% by 15–16. Here is the full curve — by age, stroke, and gender.

Across more than 680,000 Australian race results (2022–2026), the median competitive swimmer improved about 10% a year at ages 9–10, easing to about 1.5% by 15–16. Progress slows with age, but it does not suddenly stop.

Age-group swimmers improve fastest when they are young, and the rate roughly halves every few years after that. If your swimmer's improvement is slowing as they get older, that is the normal shape of development, not a warning sign. The numbers below come from over 3,000 competitive swimmers across 340+ clubs, comparing each swimmer only with their own past times.

Median year-on-year improvement by age. Shaded band is the 95% confidence range. Each swimmer is compared with their own times a year later, same event and course.

Improvement by age

Each row compares a swimmer's best time in an event at one age with their best time in the same event and course a year later. The confidence range shows how precisely we know the typical figure; individual swimmers vary widely around it, and a quieter year is common, especially in the teens.

Median year-on-year PB improvement, 50–1500m events, all strokes, LCM + SCM
Age	Median improvement	95% confidence range	Swimmers
8 → 9	12.5%	12.0% – 12.8%	640+
9 → 10	9.8%	9.5% – 10.2%	1,000+
10 → 11	8.1%	7.8% – 8.4%	1,400+
11 → 12	6.7%	6.5% – 6.9%	1,500+
12 → 13	5.2%	5.0% – 5.4%	1,400+
13 → 14	3.8%	3.7% – 4.0%	1,200+
14 → 15	2.3%	2.1% – 2.5%	850+
15 → 16	1.5%	1.4% – 1.7%	550+
16 → 17	0.8%	0.5% – 1.0%	300+

Source: SwimProgress. Method: for every swimmer we take their best time per event, course, and age (age at race date), and compare consecutive ages within the same swimmer. Figures are the median across swimmers, so each swimmer counts once per age step. Ages 17+ are excluded (sample too small to be precise). Data: publicly available Australian competition results, competitive swimmers only, anonymised and aggregated. Recomputed 16 September 2026. Reuse freely with attribution (CC BY 4.0).

Butterfly improves fastest

The more technical strokes appear to leave the most room to improve. Across ages 9–14, butterfly shows the largest median year-on-year gain and freestyle the smallest. The gap is small next to the age effect above, so treat this as useful colour rather than the headline.

Median year-on-year improvement by stroke, ages 9–14
Stroke	Median improvement	95% confidence range
Butterfly	7.1%	6.9% – 7.3%
Breaststroke	6.4%	6.2% – 6.6%
Backstroke	6.1%	5.9% – 6.3%
Individual Medley	5.9%	5.7% – 6.1%
Freestyle	5.8%	5.7% – 5.9%

Girls' biggest gains tend to come earlier

Boys and girls improve at the same rate until about age 11. From there they separate: by ages 13–14 the median girl improves about half as fast as the median boy, and by 16 girls are close to steady while boys still gain around 1% a year. This is not a sign that girls stop improving. It lines up with girls reaching the fastest phase of their adolescent growth spurt earlier than boys, on average around age 11 versus around age 13. The practical read is that the years up to about twelve are an especially valuable window for girls to make the most of, with wide individual variation throughout.

Median year-on-year improvement by gender (differences from age 11 are statistically clear)
Age	Girls	Boys
9 → 10	10.0%	9.5%
10 → 11	8.2%	8.0%
11 → 12	6.3%	7.3%
12 → 13	4.1%	6.5%
13 → 14	2.6%	5.3%
14 → 15	1.5%	3.5%
15 → 16	1.0%	2.3%

Growth-timing context: peak height velocity, the fastest phase of the adolescent growth spurt, averages around age 11 in girls and around 13 in boys (Science for Sport; NSW Office of Sport, biological-maturation resource). This describes group patterns and does not predict any individual swimmer.

What this means for your swimmer

Two practical takeaways. First, judge improvement against the right baseline: an 8% drop is ordinary for a 10-year-old and exceptional for a 15-year-old. Second, a quiet season is not a plateau problem — it is where a large share of swimmers sit every year. The signal worth watching is the trend across multiple seasons and events, not any single race.

For where your swimmer sits today, see our benchmark times by age, or use the QT calculator to check how close they are to qualifying for their next championship.

Benchmark times by event and age

Full method and data notes

Dataset. More than 680,000 publicly available Australian race results, over 3,000 competitive swimmers, 340+ clubs, 2022–2026. Family-supplied results are excluded; competitive swimmers in public results only, not all Australian children.

Measure. Within each swimmer, we take the best time per event, course, and age (age at the meet date), then compare consecutive ages in the same event and same course. Improvement is the percentage the time dropped. Long course and short course are never blended.

Aggregation. For each swimmer and age step we take the median across their events, then report the median across swimmers, so a swimmer who races many events counts once. Confidence ranges are 95% intervals for the median.

Robustness. The pattern holds when restricted to swimmers already established in an event, to swimmers with several swims at each age, to recent seasons only, and separately for each course and gender. It describes group patterns and does not predict any individual swimmer.

Reuse. Recomputed 16 September 2026. Free to reuse with attribution (CC BY 4.0).

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