Calculate Your One Rep Max
Understanding 1RM
Your One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's the foundation for calculating training weights and tracking progress.
Formulas Used:
- Epley: 1RM = Weight × (1 + Reps/30)
- Brzycki: 1RM = Weight × (36 / (37 - Reps))
- Lander: 1RM = (100 × Weight) / (101.3 - 2.67123 × Reps)
Training Zones:
| % of 1RM | Training Goal | Rep Range |
|---|---|---|
| 90-100% | Max Strength | 1-3 |
| 80-90% | Strength | 3-5 |
| 70-80% | Strength/Hypertrophy | 6-8 |
| 60-70% | Hypertrophy | 8-12 |
| 50-60% | Endurance | 12-20 |
Note: These formulas are most accurate for reps between 1-10. Higher rep ranges have more estimation error. Always use a spotter when attempting true max lifts.
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are estimates and should not replace professional medical advice.
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One Rep Max Calculator FAQ
What is One Rep Max Calculator?
One Rep Max Calculator is a free health tool that helps you Estimate 1RM from weight and reps.
How do I use One Rep Max Calculator?
Enter your input values, review the calculated output, and adjust inputs until you reach the result you need. The result updates in your browser.
Is One Rep Max Calculator private?
Yes. Calculations run locally in your browser. Inputs are not uploaded to a server by default, and refreshing the page clears session data.
Does One Rep Max Calculator require an account or installation?
No. You can use this tool directly in your browser without sign-up or software installation.
How accurate are results from One Rep Max Calculator?
This tool applies standard formulas or deterministic processing logic for estimates. For medical, legal, tax, or investment decisions, verify with a qualified professional.
Can I save or share outputs from One Rep Max Calculator?
You can bookmark this page and copy outputs manually. Results are not persisted in your account and are typically not embedded in the URL.