What is a one rep max?
Your 1RM is the heaviest weight you can lift for one technically valid rep. Most lifters rarely test it directly; a calculator estimates that number from a submaximal set instead.
Free strength tool
1RM Calculator
Estimate your one rep max from a recent working set. Pick metric or imperial, enter the weight and reps, and the calculator returns a practical 1RM estimate without saving anything.
Best for sets of 1-12 reps.
Formula comparison
-Epley
-Brzycki
-Lombardi
StatelessNo account, cookies, or stored inputs.
Guidance & reference
Understanding your one rep max
These three concepts explain what the calculator estimates, how to apply the number in training, and when a formula is enough versus a true max test.
How to use your 1RM in training
Set training percentages for top sets, strength blocks, and progression targets. For example, 85% of estimated 1RM for triples or 70% for volume work across the week.
Estimated 1RM vs true 1RM
Formulas extrapolate from a working set. A true max test is exact for that day but costs more fatigue and carries more risk. Estimates are safer for regular programming.
Ways to find your max
Each method trades accuracy, convenience, and fatigue differently. Most lifters use estimated 1RM for day-to-day training and save true max tests for specific blocks.
| Method | Best for | Accuracy | Fatigue / risk |
|---|---|---|---|
| Estimated 1RM | Regular programming from submax sets | Good for 1-8 reps | Low |
| True 1RM test | Meet prep, peaking, exact baseline | Exact for that day | Higher |
| 3RM / 5RM test | Programming anchor without full max | Very good | Moderate |
| RPE estimate | Autoregulation on fatigued days | Depends on experience | Low |
Example calculations
Two common scenarios using the Epley and Brzycki formulas averaged together, the same approach as this calculator.
Bench press: 100 kg × 5
Epley gives 117 kg, Brzycki gives 113 kg. The practical estimate sits around 113-117 kg.
≈ 113 kg estimated 1RMSquat: 140 kg × 3
Epley gives 154 kg, Brzycki gives 151 kg. Both point to a low-150s max.
≈ 154 kg estimated 1RMRelated calculators
Combine your estimated max with nutrition and strength benchmarks for a fuller training picture.
1RM calculator FAQ
Quick answers about accuracy, rep ranges, and when to test a true max.
How accurate is a 1RM calculator?
For sets of 1-8 reps with good technique, estimated 1RM is usually within a few percent of a true max. Accuracy drops above 10 reps or when form breaks down.
Which 1RM formula is best?
Epley and Brzycki are the most common for strength training. This calculator shows both plus Lombardi so you can compare. For most lifters, the average of Epley and Brzycki is a practical estimate.
How many reps should I use to estimate 1RM?
Sets of 3-8 reps give the most reliable estimates. A hard set of 5 is a common choice because it is heavy enough to be meaningful but not so close to max that technique suffers.
Should I test a true 1RM or use an estimate?
Use estimates for everyday programming and track trends over time. Test a true max only when you need an exact number, such as before a meet or after a dedicated peaking block.
Can I use estimated 1RM for strength standards?
Yes. Estimate your max from a recent working set here, then compare it on the strength standards chart to see how you rank relative to bodyweight.