One Rep Max Calculator

Test your 1RM when: 1) You've been consistently training for at least 6-12 months, 2) You've mastered proper form for the exercise, 3) You're well-rested and not fatigued, 4) It's been at least 4-6 weeks since your last test, and 5) You have proper safety equipment and spotters available. Avoid testing when injured, overtrained, or significantly stressed. Most programs recommend testing every 12-16 weeks to track progress effectively.

Different formulas have varying accuracy depending on factors like exercise type and rep range. The Brzycki formula (used here) is most accurate for 1-10 reps and compound movements. Epley's formula tends to be more accurate for higher reps (10+). Lombardi's formula works well for isolation exercises. The most accurate predictions come from using lower rep ranges (1-5) regardless of the formula used. Always treat predictions as estimates and approach new maximal attempts conservatively.

Key safety guidelines include: 1) Proper warm-up with progressively heavier weights, 2) Having experienced spotters for certain lifts, 3) Using safety equipment like power racks and safety pins, 4) Maintaining strict form throughout the lift, 5) Never testing when fatigued or injured, 6) Following a proper progression plan, and 7) Having a plan for failed attempts. Always prioritize form over weight and listen to your body's signals.

Optimal rest periods between maximal attempts are: 1) 48-72 hours minimum between heavy training sessions, 2) 7-10 days between true 1RM attempts of the same exercise, 3) 4-6 weeks between comprehensive testing sessions, and 4) Include deload weeks every 4-8 weeks. Recovery needs may vary based on training experience, age, nutrition, and sleep quality. Signs you need more rest include decreased performance, persistent fatigue, and joint discomfort.