Why does the curve peak at 28?

Across multiple population studies of recreational and competitive lifters, neuromuscular output peaks somewhere between ages 26 and 30 and then declines slowly. We use 28 as the round-number peak. After that, you lose roughly 1 percent per year as a default, faster if you are sedentary and slower if you keep training.

How is the score calculated?

We take the sum of your three lifts with weight bench × 1.25 and deadlift × 0.85, divided by your bodyweight. The weights reflect the relative neuromuscular cost of each lift. The result is a single number, normalized to bodyweight, that we compare against a population peak of 5.5 for men and 3.6 for women.

Why are bench and deadlift weighted differently?

Bench is harder per pound relative to bodyweight than squat or deadlift, so bench × 1.25 keeps strong benchers from being penalized. Deadlift is easier per pound relative to bodyweight (more leverage, full posterior chain), so deadlift × 0.85 prevents big deadlifters from running away with the score.

What about the lifestyle modifiers?

Each modifier toggles a year-delta on top of the calculated strength age. Most are conservative. Chronic poor sleep ages you about three years, smoking five years, eating enough protein knocks one year off. They are not science-grade adjustments. They are conversation starters about which lifestyle inputs are dragging your real-world performance.

I scored a strength age of 18. Is that good?

It means your composite score is in the top quartile of adult lifters. Whatever you are doing is working. The risk now is staying there. Strength compounds when programmed and leaks when winged. The verdict in your result tells you what we would change first.

What's your strength age?

Free strength age calculator. Plug in your three big lifts plus bodyweight and see the age your nervous system actually trains at, against a population curve that peaks at 28.

3 lifts · ~30s

Strength across the lifespan

male model

Sex

sets the curve

Units

Your age

yrs

Bodyweight

Best single rep on each

Squat

Bench

Deadlift

Anything else true of you

optional

See how your plan gets built

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How this works

Strength age is a benchmark you can read in one second. We score your three lifts against a population curve that peaks at 28, then spread the result across a 60-year span: the closer you sit to the peak, the younger the number. It is a rescaling of one score, not a lookup of where you would fall on the curve, so read it as a dial rather than a birthday.

The inputs are deliberately small. Three lifts plus bodyweight plus age. The math is transparent and the modifiers are blunt. This tool is calibration, not diagnosis.

Compute the composite score
We take squat plus bench × 1.25 plus deadlift × 0.85, divided by bodyweight. The weighting normalizes for the relative neuromuscular cost of each lift so a strong bencher with a weak squat does not get penalized.
Compare against the population peak
Population peak score is 5.5 for men, 3.6 for women, both at age 28. Your ratio against that peak determines whether your strength age is younger than 28 (above the peak) or older (below it). The math is symmetric.
Place on the lifespan curve
The curve ramps up linearly from age 15 to peak at 28, then decays roughly 1 percent per year. Your score gets plotted at the age where the population would naturally produce that score. That age is your strength age.
Apply lifestyle modifiers
Optional adjustments stack on top of the score-based number. Sleep, injury, smoking, alcohol, sedentary work, protein intake, and consistency each shift the result by a few years. Most lifters apply zero or one. The curve does most of the work.

This is a benchmark, not a diagnosis. A 35-year-old with a strength age of 25 is in great shape but should still see a doctor about the chest pain. A 25-year-old with a strength age of 45 is not actually 45 years old. They just lift like one.

Common questions

Strength age is the age the population curve says your composite lifting score corresponds to. It is not your real age. It is a benchmark. If your three lifts together produce a score that the average 25-year-old produces, your strength age is 25, regardless of what your driver's license says.

All free tools

What's your strength age?

Strength across the lifespan

Sex

Units

Best single rep on each

Anything else true of you

How this works

Compute the composite score

Compare against the population peak

Place on the lifespan curve

Apply lifestyle modifiers

Common questions

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Print your lifetime tonnage

What kind of lifter are you?

Strength across the lifespan

Sex

Units

Best single rep on each

Anything else true of you

How this works

Compute the composite score

Compare against the population peak

Place on the lifespan curve

Apply lifestyle modifiers

Common questions

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