One Rep Max — Estimate from Submaximal Reps
7 formulas: Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner, Wathan. Best accuracy at 1–10 reps. Percentage table 95% to 50% for programming. NSCA, ExRx.net, JSCR.
Why This Stat Matters
Why: 1RM sets training loads (e.g., 80% of 1RM for 5×5). Brzycki and Epley most used. Accuracy drops above 10 reps.
How: Enter weight and reps. Choose formula. Get 1RM and percentage table (95% to 50%) for programming.
- ●Brzycki and Epley most accurate at 1–10 reps
- ●5–10% error vs actual 1RM in research
- ●Percentage table for 5×5, 5/3/1, etc.
📋 Quick Examples — Click to Load
📊 Formula Comparison
7 formulas
📈 Percentage Table
95% to 50%
🥧 Accuracy by Rep Range
Typical error %
📊 1RM by Reps
Brzycki at different reps
For educational and informational purposes only. Verify with a qualified professional.
🏅 Sports Records
Brzycki and Epley most used; 5–10% error vs actual 1RM
Best accuracy at 1–10 reps; drops above 10
Percentage table: 95%, 90%, 85%... for programming
Estimate 1RM from submaximal reps using 7 formulas: Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner, Wathan. Best accuracy at 1–10 reps. 1RM testing has 5–10% error with formulas vs actual. Brzycki and Epley are most used. Also generates percentage table (95% to 50%) for programming.
Sources: NSCA, ExRx.net, Journal of Strength & Conditioning Research.
Key Takeaways
- • 7 formulas: Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner, Wathan.
- • 1RM formulas have 5–10% error vs actual. Best at 1–10 reps.
- • Brzycki and Epley are most used. Accuracy drops above 10 reps.
- • Elite powerlifters rarely use formula-based 1RM—they test directly.
Did You Know?
How Does 1RM Estimation Work?
Brzycki & Epley
Brzycki: 1RM = weight × 36/(37−reps). Epley: 1RM = weight × (1+reps/30). Both most used. Best 1–10 reps. NSCA standard.
Lander & Mayhew
Lander: 1RM = w/(1.013−0.027r). Mayhew: exponential decay. Research-based. Good for 1–10 reps.
Percentage Table
95%, 90%, 85%... down to 50%. Used for programming. 5×5 at 80%, 3×3 at 90%, etc. This calculator generates it from your 1RM.
Expert Tips
Formula Comparison
| Formula | Best For | Accuracy |
|---|---|---|
| Brzycki | 1–10 reps | ✅ High |
| Epley | 1–10 reps | ✅ High |
| 10+ reps | All | ❌ Lower |
Frequently Asked Questions
What is a one-rep max (1RM)?
The maximum weight you can lift for one repetition with good form. Used to set training loads (e.g., 80% of 1RM). Can be tested directly or estimated from submaximal reps using formulas. Best accuracy at 1–10 reps.
Which 1RM formula is most accurate?
Brzycki and Epley are most used. Research shows 5–10% error vs actual 1RM. Accuracy drops significantly above 10 reps. Compare multiple formulas for a range. Lander and Mayhew are also research-based.
What is the Brzycki formula?
1RM = weight × 36 / (37 − reps). Published 1993. Most accurate 1–10 reps. Tends to underestimate at higher reps. NSCA standard. Widely used in strength coaching.
What is the Epley formula?
1RM = weight × (1 + reps/30). Simpler than Brzycki. Often gives slightly higher estimates. Both are industry standards. Good for quick estimates.
Why does accuracy drop above 10 reps?
Formulas assume a linear or exponential relationship between reps and % 1RM. At 15+ reps, fatigue and technique vary more. Use 1–10 reps for best estimates. Elite powerlifters rarely use formula-based 1RM.
What is a percentage table?
Shows weight at each % of 1RM: 95%, 90%, 85%, etc. Used for programming (e.g., 5×5 at 80%). This calculator generates 95% down to 50% for training reference.
Key Statistics
Official Data Sources
⚠️ Disclaimer: This calculator is for educational purposes only. 1RM formulas have 5–10% error. Consult a qualified coach before max testing. Not medical or training advice.