The Complete Guide to Estimating Your One-Rep Max
By Arshi Khan, Founder of Just4Marketing · Last reviewed October 2026
Your one-rep max (1RM) is the most weight you can lift for a single repetition with good form. Testing it directly is tiring and carries more injury risk, so most lifters estimate it from a heavier set of several reps. This guide explains the two most widely used formulas, how accurate they are, and how to turn a 1RM into training weights.
Why estimate instead of test
A true max attempt needs a long warm-up, full recovery, and ideally a spotter, and a failed attempt at a heavy weight is where injuries tend to happen. An estimate from a hard set of 3–6 reps lands close to a real max for most people, and you can update it every few weeks as you get stronger without ever attempting a single.
Training zones as a share of 1RM
| % of 1RM | Typical reps per set | Main training effect |
|---|---|---|
| 90–100% | 1–3 | Maximal strength, competition practice |
| 80–90% | 3–6 | Strength |
| 70–80% | 6–10 | Muscle size and strength |
| 60–70% | 10–15 | Muscle size and endurance |
| 50–60% | 15+ | Technique, warm-ups, and endurance |
Getting reliable numbers
Use a set taken close to failure
If you could have done three more reps, the estimate will be too low.
Keep form consistent
Half reps or bouncing the weight inflate the result and won't match what you can really lift.
Estimate each lift separately
A squat, bench press, and deadlift 1RM all differ; don't use one to set weights for another.
Re-estimate every few weeks
Training weights based on an old max become too light as you progress.
Frequently asked questions
What is the Epley formula?
Epley estimates 1RM = weight × (1 + reps ÷ 30). Lifting 100 kg for 5 reps gives about 116.7 kg. It tends to give slightly higher estimates than Brzycki as the reps increase.
What is the Brzycki formula?
Brzycki estimates 1RM = weight × 36 ÷ (37 − reps). The same 100 kg × 5 gives 112.5 kg. Averaging Epley and Brzycki smooths out the difference between them.
How many reps give the most accurate estimate?
Sets of about 3 to 6 reps taken close to failure are the most reliable. Above roughly 10 reps, endurance plays a bigger role and estimates can be well off.
Is it safe to test a true one-rep max?
It can be for experienced lifters with good technique, a proper warm-up, and a spotter or safety bars. Beginners usually get more benefit — and less risk — from estimating it.