One Rep Max Calculator
Estimate your 1RM using 7 proven strength formulas
Between 1 and 30 reps
Using Your 1RM to Structure Smarter Training
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with proper form. Beyond being a bragging right, it's the reference number that makes structured strength programming possible — every percentage-based program (5/3/1, Starting Strength, Greyskull LP, most powerlifting templates) depends on knowing your 1RM.
For most trainees, testing a true 1RM isn't worth the injury risk and recovery cost. Estimating it from submaximal work is safer and nearly as accurate. The Epley and Brzycki formulas use your reps at a given weight to predict your 1RM within 3-5% for most people in the 3-10 rep range. Accuracy drops above 10 reps — high-rep max attempts tell you more about muscular endurance than true strength. If you bench 225 lbs for 5 clean reps, your estimated 1RM is roughly 260 lbs.
Knowing your 1RM unlocks percentage-based training. Hypertrophy work lives at 65-80% of 1RM for 6-12 reps. Strength work uses 80-92% for 3-6 reps. Peaking work pushes above 92%. The scientific literature (Schoenfeld et al., 2017) shows that hitting a minimum weekly volume at appropriate intensities drives progress — not maximum effort every set. A 1RM gives you the anchor for applying these principles.
Re-test every 8-12 weeks. Newer lifters gain quickly — a 1RM from 3 months ago is often already outdated. Intermediate and advanced lifters progress slower, so longer re-test windows are fine. Use your estimated 1RM to program your next training block, track progressive overload, and spot plateaus early. When three consecutive blocks show no 1RM increase despite consistent training, it's time to change variables: exercise selection, volume, or recovery protocols.
Keep learning
- →One-Rep Max Guide for Strength TrainingFull guide to testing, estimating, and applying your 1RM.
- →Progressive Overload ExplainedThe principle that drives every 1RM increase.
- →Strength Training Beginner's GuideStarting from zero? Begin here.
- →Best Creatine Monohydrate 2026The single best-studied supplement for increasing 1RM.
One-Rep Max FAQ
Your one-rep max is the maximum weight you can lift for a single repetition with proper form. It is used to program training intensities — for example, working at 70-85% of your 1RM for hypertrophy or 85-95% for strength.
Testing a true 1RM carries higher injury risk, especially for beginners. Using an estimated 1RM calculated from a sub-maximal set (e.g., 5 reps at a given weight) is safer and nearly as accurate. Save true 1RM testing for competition prep or after several months of consistent training.
No single formula is universally best. The Epley and Brzycki formulas are most widely used and tend to be accurate for sets of 1-10 reps. Accuracy decreases with higher rep counts (15+). Our calculator uses multiple formulas and shows the average for the most reliable estimate.
Recalculate every 4-6 weeks or whenever you notice your working weights have changed significantly. Strength improves with training, and your percentages should update accordingly to continue progressing.