What a one rep max is
Your one rep max, or 1RM, is the most weight you can lift for a single clean rep of an exercise. Strength programs use it to set training loads, like 5 sets of 5 at 80%. Testing a true max is hard on the body and takes a full session, so most lifters estimate it from a lighter set they can do for several reps. This calculator does that with three well known formulas and shows the average.
Example: 225 lb for 5 reps. Epley gives 225 × (1 + 5 ÷ 30) = 262.5 lb, Brzycki 225 × 36 ÷ 32 = 253.1 lb, and Lombardi 225 × 50.10 = 264.3 lb. The average is about 260 lb. With a single rep, every formula returns the weight you lifted.
How to use the percentages
Programs often write loads as a percent of your 1RM, because that scales to any lifter. Find the percent in the chart and lift the weight next to it. The rep column is the Epley formula solved for reps, a rough guide to how many reps you could do at that weight if you went all out. In training you usually stop one to three reps short of that.
| % of 1RM | Max reps, about | Typical use |
|---|---|---|
| 95% | 2 | Heavy singles and doubles |
| 90% | 3 | Heavy strength work |
| 85% | 5 | Strength |
| 80% | 8 | Strength |
| 75% | 10 | Strength and muscle |
| 70% | 13 | Muscle building |
| 65% | 16 | Muscle building, technique |
| 60% | 20 | Technique, warm up sets |
| 50% | 30 | Warm up sets |
The rep counts get less reliable at lower percentages. Some people can do many more reps at 60% than the chart says, others fewer. Use the chart as a starting point and adjust to how the sets feel.
Bench press, squat and deadlift
Estimate each lift on its own, since your squat max says nothing about your bench press. For the deadlift, a set of 3 to 5 is usually better than a long set, because grip and lower back tire before the legs do. Retest every few weeks with a fresh set, so your percentages keep up with your strength.
Lifting safely
- Warm up: do a few lighter sets before the test set, building up in weight.
- Use safety gear: a spotter or safety bars for the bench press and squat, collars on the bar.
- Keep form first: end the set when your form breaks down, not when you can no longer move the bar.
- Check with a doctor: if you have a heart condition, high blood pressure, an injury or another health condition, talk to your doctor before heavy lifting.
How to use the one rep max calculator
- 1Choose lbs or kg and enter the weight you lifted.
- 2Enter how many clean reps you did, from 1 to 12. A hard set of 3 to 6 reps gives the best estimate.
- 3Read your estimated 1RM and the training weights in the percentage chart, rounded to plates or exact. Copy the result or a link.
Frequently asked questions
How is a one rep max calculated?
From a set you can already do. Lift a weight for as many clean reps as you can, then put the weight and reps into a formula. Epley is weight × (1 + reps ÷ 30), so 225 lb for 5 reps gives 225 × 1.1667 = 262.5 lb. The calculator also runs Brzycki and Lombardi and shows the average of the three.
Which 1RM formula is the most accurate?
None is best for everyone. The formulas agree closely for sets of about 2 to 6 reps and drift apart as the reps go up, because people differ in how well they keep going near failure. Averaging three formulas evens out their quirks. Your own track record, like a real single you did recently, is always the better number.
How many reps should my test set have?
A set of 3 to 6 reps taken close to failure, with good form, gives the most reliable estimate. Sets above 10 reps say more about your muscular endurance than about your maximal strength, so the calculator shows a warning there and stops at 12.
Is it safe to test my real one rep max?
An actual max attempt puts a lot of load on joints and the back, and form breaks down easily. That is why many lifters estimate it instead. If you do test, warm up well, use a spotter or safety bars on the bench press and squat, and stop when the bar speed slows a lot. Beginners are better off building up with sets of 5 or more.
Can I use the same 1RM for every lift?
No. Each exercise has its own max, so estimate your bench press, squat and deadlift separately. The formulas work best for big barbell lifts. For machines, curls and other small exercises, the estimates are rougher.