1RM calculator: your estimated one-rep max
Your 1RM — one-repetition maximum — is the heaviest weight you can lift once with correct technique. You do not need to test it to know it: one set is enough to estimate it.
Estimated 1RM
114.5 kg
| % of 1RM | Weight | Reps |
|---|---|---|
| 100 % | 115 kg | 1 |
| 95 % | 110 kg | 2 |
| 93 % | 107.5 kg | 3 |
| 90 % | 102.5 kg | 4 |
| 87 % | 100 kg | 5 |
| 85 % | 97.5 kg | 6 |
| 83 % | 95 kg | 7 |
| 80 % | 92.5 kg | 8 |
| 77 % | 87.5 kg | 9 |
| 75 % | 85 kg | 10 |
| 70 % | 80 kg | 11 |
| 67 % | 77.5 kg | 12 |
| 65 % | 75 kg | 15 |
Weights rounded to 2.5 kg. Reps: NSCA reference average.
How the calculation works
The calculator applies two published formulas and averages them: Epley (1RM = weight × (1 + reps ÷ 30)) and Brzycki (1RM = weight × 36 ÷ (37 − reps)). They agree closely up to about ten reps.
Beyond 10 reps the estimate becomes unreliable: endurance then matters as much as strength, and it varies a lot from person to person. That is why the calculator stops at 12. For an accurate estimate, use a heavy set of 3 to 6 reps taken close to failure with clean technique.
The table shows, for each percentage of your max, the number of reps the average lifter completes, from the NSCA (National Strength and Conditioning Association) reference table. Weights are rounded to 2.5 kg, the finest jump 1.25 kg plates allow.
Using your 1RM to program
Strength programs are written as percentages of your max. The NSCA guidelines:
- 85% and above — 1 to 6 reps: maximal strength work.
- 67 to 85% — 6 to 12 reps: volume and muscle growth.
- Below 67% — warm-ups, technique, speed.
- For a beginner, the max changes fast: recalculate it every four to six weeks from your recent sets.
Testing a true max, safely
The estimate is enough to program with. If you still want to test a true 1RM:
- Never alone on squat or bench: safety bars set, or a spotter who knows what they are doing.
- Work up in steps: several sets of fewer and fewer reps, then singles 3 to 5 minutes apart.
- Aim for the estimate, not beyond, and stop as soon as technique breaks down: a cleanly missed attempt beats an ugly max.
- Wear your belt on heavy squat and deadlift attempts, set and tested during warm-ups.
Frequently asked questions
What is a 1RM?
The maximum weight you can lift once, with correct technique, on a given lift. It is used to measure strength and to calculate the weights in a program.
Is a 1RM calculation accurate?
It gives a good estimate from a set of 3 to 6 reps taken close to failure. It gets less accurate beyond 10 reps, and depends on your profile: a very enduring lifter will do more reps than average at the same percentage.
Which formula does this calculator use?
The average of the Epley and Brzycki formulas, the two most widely used. For a single rep, the result is the weight itself.
Do I need a separate 1RM for each lift?
Yes. Squat, bench press and deadlift each have their own max, and the ratio between them varies from lifter to lifter.
Should I calculate my 1RM with or without a belt?
In the conditions you train in. A well-used belt usually lets you lift a little heavier: if your heavy sets are belted, your reference max should be too.
On heavy sets, the belt
Above 80% of your max, a uniform-width leather belt helps keep your torso rigid. QOWA belts: genuine leather, 10 cm all the way round, lever buckle, in 10 mm and 13 mm.
Delivered anywhere in Algeria, to your door or a pickup point, cash on delivery.