Your one rep max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's the foundational metric of strength training — used to set training loads, measure progress, and compare performance across different lifters and programs.
Why Your 1RM Matters
Most evidence-based strength programs prescribe loads as a percentage of your 1RM. For example, 5×5 at 80% 1RM, or 4×8 at 70% 1RM. Without knowing your 1RM, you're guessing at intensity — and either undertrain (too easy) or overtrain (too hard for recovery).
How to Test Your 1RM Safely
Direct 1RM testing should only be attempted by those with at least 6 months of consistent training experience and good technique. Never test a true max alone — always have a competent spotter.
- Warm up thoroughly: 5–10 min light cardio, then progressively loaded warm-up sets
- Attempt a weight you're confident you can lift for 3–5 reps
- Rest 3–5 minutes between heavy attempts
- Increase by 5–10% each attempt until you reach failure
- Limit total attempts to 3–5 to avoid cumulative fatigue
For beginners, exercises with higher injury risk at maximal loads (e.g. barbell squat, deadlift) should be estimated from submaximal lifts rather than tested directly. Save true 1RM testing for when your technique is bulletproof.
Calculate 1RM Without Maxing Out
Several validated formulas estimate your 1RM from a set of reps performed to technical failure:
- Epley Formula: 1RM = Weight × (1 + Reps/30)
- Brzycki Formula: 1RM = Weight / (1.0278 − 0.0278 × Reps)
- Lander Formula: 1RM = (100 × Weight) / (101.3 − 2.67123 × Reps)
Example: If you lifted 100 kg for 5 reps, the Epley formula gives: 100 × (1 + 5/30) = 116.7 kg estimated 1RM.
These formulas are most accurate for 3–8 rep ranges. Above 10 reps, accuracy decreases significantly.
Using Percentages in Your Training
- 50–60% 1RM: Warm-up, technique work, recovery
- 65–75% 1RM: Hypertrophy (muscle building), 8–15 reps
- 75–85% 1RM: Strength-hypertrophy, 4–8 reps
- 85–95% 1RM: Maximal strength, 1–5 reps
- >95% 1RM: Peak performance, competition attempts
Calculate Your 1RM Instantly
Enter the weight and reps you lifted to get your estimated one rep max for any exercise.
Open 1RM Calculator →The Bottom Line
Your 1RM is the anchor of intelligent strength programming. Test it directly when experienced and comfortable, or estimate it safely from submaximal efforts. Retest every 6–12 weeks to update your training percentages as you get stronger.