1RM Calculator: One Rep Max Guide for Strength Training
Your One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's the gold standard for measuring strength and the foundation of every effective training program.
Three 1RM Formulas
1. Epley Formula
Best for moderate rep ranges (5–10 reps):
1RM = weight × (1 + reps/30)
2. Brzycki Formula
Best for low rep ranges (1–5 reps):
1RM = weight × 36 / (37 - reps)
3. Landers Formula
An alternative that works well across rep ranges:
1RM = (100 × weight) / (101.3 - 2.67123 × reps)
Our calculator shows all three side by side and gives you the average for the most reliable estimate.
The Percentage Table
Once you know your 1RM, you can program your workouts using percentages:
| % 1RM | Reps | Purpose |
|---|---|---|
| 100% | 1 | True max (test only) |
| 95% | 2 | Heavy strength |
| 90% | 4 | Strength |
| 85% | 6 | Strength-hypertrophy |
| 80% | 8 | Hypertrophy |
| 75% | 10 | Hypertrophy |
| 70% | 12 | Muscular endurance |
| 65% | 15 | Endurance |
Common Training Programs
| Program | Sets × Reps | % 1RM |
|---|---|---|
| 5×5 (Starting Strength) | 5 × 5 | 80–85% |
| German Volume Training | 10 × 10 | 60–65% |
| 5/3/1 (Wendler) | varies | 65–95% |
| Powerlifting peaking | 3 × 3 | 90–95% |
| Bodybuilding | 3 × 8–12 | 70–80% |
How to Test Your 1RM Safely
Method 1: Direct Testing (Advanced)
- Warm up with 5–10 minutes of light cardio
- Do 2 warm-up sets with light weight (50%, 70% of estimated 1RM)
- Attempt your estimated 1RM
- If successful, add 2.5–5 kg and try again after 3–5 min rest
- Stop when you fail a rep
Method 2: Submaximal Test (Safer)
- Choose a weight you can lift for 3–10 reps
- Lift to near-failure (leave 1 rep in reserve)
- Use our calculator to estimate 1RM
Always use a spotter for bench press and squats.
Tips for Accurate 1RM Estimation
- Use 1–10 reps for best accuracy
- Higher reps (>10) are less reliable due to muscular endurance factors
- Brzycki is most accurate for 1–5 reps
- Epley works well for 5–10 reps
- The average of all three formulas is usually closest to your true max