Your true 1RM, without the grind
Estimate your max from a set you can actually do safely.
Results update as you type 🥑
How to use your 1RM
Your one-rep max is the most you could lift for a single rep. Estimating it from a submaximal set is safer than testing a true max and accurate enough for programming.
We average the Epley and Brzycki formulas. Accuracy is best at 1–10 reps; beyond that, fatigue and form drift make any estimate noisy.
Use the percentage table to set working loads: roughly 75–85% for hypertrophy, 85–95% for strength, 60–70% for speed and technique work.
Common questions
How accurate is an estimated 1RM?
Within a few percent for sets of 1–6 reps. Higher rep sets are less reliable because endurance varies more between people.
Should I test a true 1RM instead?
Rarely necessary and higher risk. An estimate from 3–5 reps is enough to program effectively for most lifters.
Which formula is best?
They are close. We show the average of Epley and Brzycki; differences are minor at low reps.
Is my data stored?
No. Everything is calculated in your browser. Nothing is sent to a server or saved.
Sources & references
- Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults.” J Am Diet Assoc. 2005;105(5):775–789.
This calculator provides estimates for general educational use and is not medical advice. Consult a qualified professional before making significant dietary changes.