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One rep max calculator.
Take a set you have genuinely done and get your estimated one rep max, plus the percentages you would actually train off. No need to grind out a true single to find out.
How this is worked out
The formula. Epley: your 1RM is the weight lifted multiplied by (1 + reps ÷ 30). Five reps at 100 kg estimates a 117 kg max. It is the same sum the Whey to Go app uses to track your estimated max over time, so a number here and a PR in the app will always agree.
Why it stops at {max} reps. Every 1RM formula drifts as the reps climb, because a high-rep set measures endurance as much as strength. Past about a dozen reps the arithmetic starts flattering you into a max you could not actually lift, so this refuses to give one rather than hand you a fantasy number.
What the percentages are for. A 1RM on its own is a trophy. The table is the useful part: most strength programmes are written as percentages of it, so this is what you would put on the bar. Treat the rep counts as the usual working range at each load, not a target to fail at.
It is an estimate, and it flatters some lifts. Deadlifts and squats tend to hold up better at higher reps than bench or overhead press, so a 10-rep bench estimate will usually read a little high. If you want a true max, work up to one properly, with a spotter, on a day you are fresh.
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This is an estimate and a starting point, not medical advice. Every equation of this kind is a population average, so your real burn can sit a few hundred kcal either side of it. Track for two or three weeks and adjust to what actually happens on the scales. If you are pregnant, managing a health condition or unsure, speak to a doctor or dietitian first.
There is no account here and no tracking cookie, so nothing you enter is saved to a profile or tied to you. The sums run on our server, and your answers travel in the page address, which is what makes a result shareable. Treat a link you send as carrying those numbers with it.
Now log against it
A number is only useful if you can hit it. Whey to Go tracks food and training against targets like these, on your device, with no account and nothing sold.