TOOLEstimate your max without maxing out
Testing a true one rep max is taxing and risky, so most lifters estimate it. Enter a weight and the number of reps you completed with good form and this tool predicts your 1RM using two trusted formulas — Epley and Brzycki — then shows the average. Estimates are most reliable when your set is under about ten reps.
The formulas
The percentage table turns your 1RM into working weights: heavy singles and triples sit up near 90–95%, hypertrophy work lives around 67–75%, and endurance sets sit lower. Use it to program a session, then check the macro calculator to fuel it.
Estimates are for general training use only and are not a substitute for coaching. Warm up thoroughly, use a spotter for heavy lifts, and stop if your form breaks down.
How to test your rep max safely
- Warm up thoroughly with light sets before the working set you'll enter.
- Pick a weight you can lift 3–8 times with solid form — estimates are most accurate in this range and far safer than a true single.
- Take that set close to failure but stop the moment form breaks down.
- Enter the weight and honest rep count above to get your estimated 1RM and the full percentage table.
- Use a spotter or safety pins for barbell lifts, and re-test every few weeks rather than every session.
Turning your 1RM into a program
The percentage table is where the estimate earns its keep. Say the tool returns a 140 kg estimated max on the squat. Heavy strength work sits at 85–95% (about 119–133 kg for low reps), hypertrophy work lives around 67–75% (roughly 94–105 kg for sets of 8–12), and speed or technique work stays lighter still. Programming from percentages keeps your effort consistent as you get stronger — you just re-test and the working weights scale up with you.
Strength is built in the kitchen too: set your energy needs with the TDEE calculator, hit your protein with the macro calculator, and manage conditioning intensity with the target heart rate calculator.
Frequently asked questions
What is a one rep max?
Your one rep max, or 1RM, is the most weight you can lift for a single repetition of an exercise with good form. It is a common way to measure strength and to set training loads as a percentage of that maximum.
How is 1RM estimated without a max attempt?
Formulas predict your 1RM from a set you can already do. Enter the weight and how many reps you managed and the tool applies the Epley and Brzycki equations. Estimates are most accurate at lower rep counts, ideally under about ten reps.
Why do the two formulas give different numbers?
Epley and Brzycki model the weight-to-reps relationship slightly differently, so they diverge a little, especially at higher reps. Showing both gives you a sensible range, and the average is a reasonable single figure to work from.