One Rep Max Calculator
Enter the weight and reps of a hard set to estimate your one-rep max — and get the training weights for every percentage your program asks for, rounded to plates you actually have.
Estimated 1RM: –
| % of 1RM | Weight | About |
An estimate, not a guarantee. Lift heavy only with safety arms or a spotter, and stop a set when your form breaks down.
How to get a good estimate
- Warm up with a few lighter sets.
- Pick a weight you can lift for about 3–6 clean reps and do one set, stopping when the next rep would be a grind.
- Enter the weight and reps above. Use the percentage table to plan your next sessions.
Training at home? A power rack with safety arms is the most important piece of safety gear for heavy lifts — see our strength equipment guides. Programs and technique tips are in Training Guides.
Questions
What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. Many training programs prescribe weights as a percentage of it, for example 3 sets of 8 at 75%. You do not need to test it directly: a set of a few reps to near failure gives a good estimate.
How accurate is a 1RM calculator?
Estimates are most accurate from sets of about 2–10 reps taken close to failure. The calculator averages two widely used formulas (Epley and Brzycki). Results vary between people and lifts, so treat the number as a guide and adjust by feel.
Is it safe to test my real one-rep max at home?
Only with proper safety: a power rack or squat stand with safety arms set just below the bottom of the lift, or an experienced spotter. Warm up well and stop if your form breaks down. For most home lifters, estimating from a heavy set of 3–5 reps is safer and good enough for programming.
What percentage of my 1RM should I train with?
As a rough guide: about 85–95% of 1RM for heavy sets of 1–5 reps (strength), 70–85% for sets of 6–12 (muscle growth), and 50–70% for lighter sets of 12 or more and technique practice.
Should I use the same max for every exercise?
No. Calculate a separate max for each lift — squat, bench press, deadlift and overhead press can be very different. Re-check every few weeks as you get stronger.