One Rep Max Calculator
Estimate your one-rep max (1RM) using multiple proven formulas. Enter the weight lifted and number of reps performed.
Estimated 1RM (Average)
258.3 lbs
Epley
262.5
Brzycki
253.1
Lombardi
264.3
O'Conner
253.1
Training Load Table
1 rep (100%)
258.3 lbs
2 reps (95%)
245.3 lbs
3 reps (93%)
240.2 lbs
4 reps (90%)
232.4 lbs
5 reps (87%)
224.7 lbs
6 reps (85%)
219.5 lbs
8 reps (80%)
206.6 lbs
10 reps (75%)
193.7 lbs
12 reps (70%)
180.8 lbs
15 reps (65%)
167.9 lbs
20 reps (60%)
155.0 lbs
How 1RM Estimation Works
One-rep max (1RM) estimation formulas use the weight you lift and the number of repetitions to estimate the maximum weight you could lift for a single rep. These are most accurate for 2-10 reps; higher rep ranges reduce accuracy.
Features
- 4 estimation formulas (Epley, Brzycki, Lombardi, O'Conner)
- Rep percentage table for programming
- Supports lbs and kg
- Average across all formulas
Disclaimer: This tool is provided “as is” for informational and educational purposes only. Results may not be 100% accurate. ToolBird makes no warranties, express or implied, regarding the accuracy, reliability, or completeness of any output generated by this tool. This tool does not constitute professional, legal, financial, medical, or tax advice. Always consult a qualified professional for important decisions. By using this tool, you agree that ToolBird and its operators shall not be held liable for any damages, losses, or consequences arising from the use of this tool or reliance on its results. All processing occurs in your browser — we do not store, transmit, or access your data. Use at your own risk.