Editorial policy

We base every figure here on a formula that has been published, or on a study we can point readers toward.

Where the numbers come from

• All seven formulas are published equations by Epley, Brzycki, Lombardi, O'Conner, Wathen, Mayhew and Lander.
• Our accuracy figures come from the 1997 LeSuer study, and we used the original paper.
• You'll find a link to every source on the methodology page.

The calculator gets checked

Before every release, worked examples are run against the calculator. Worked examples include 225 lb × 10 = 300 lb and 100 kg × 8 = 126.5 kg. If any result changes, we hold the release until the problem is fixed.

What we leave out

We don't publish strength standards or "how strong are you" rankings. A good one needs your sex, your bodyweight and a large group of lifts you've actually done. We'd rather send you to a published table than guess.

Independence

No brand, gym or supplement company pays for anything here. You won't see any product placed beside your result.

Corrections

If you spot a mistake, email contact@benchprcalculator.com with the weight and reps you entered. We check it against the formulas, and if we got it wrong, we correct the site.