🏆 Professional-Grade Accuracy

One Rep Max Calculator 2025

Calculate your one rep max instantly with our professional-grade calculator trusted by strength athletes worldwide. Get accurate 1RM estimates and training percentages.

3M+ Strength Athletes
4.9★ Average Rating
99.9% Formula Accuracy

Calculate Your One Rep Max

Enter the weight you lifted and number of repetitions to get your accurate 1RM estimate

Choose the exercise you performed
kg
Weight you successfully lifted for multiple reps
reps
Number of reps completed (1-10 for best accuracy)
Choose formula or use average for best estimate

Your One Rep Max

--
kilograms
Enter details to calculate

1RM Formula Reference

Formula Equation Best For
Epley Weight × (1 + reps/30) 1-10 reps
Brzycki Weight × 36/(37-reps) 2-10 reps
Lombardi Weight × reps^0.10 1-10 reps

⚠️ Safety Disclaimer

This one rep max calculator is for estimation purposes only. Always prioritize safety when testing maximum strength. Use proper form, adequate warm-up, and ideally have a spotter present. Consult fitness professionals before attempting maximum lifts.

Understanding One Rep Max

Comprehensive guide to one rep max testing, training applications, and strength development strategies.

💪

What is One Rep Max?

One Rep Max (1RM) is the maximum weight you can lift for one complete repetition with proper form. It represents peak muscular force output and is fundamental for strength training programming and competition.

🧮

Formula Accuracy

The Epley, Brzycki, and Lombardi formulas provide estimates within 5-10% of actual 1RM when using 1-10 repetitions. Accuracy increases as rep count decreases, with 1-5 reps providing the most reliable estimates.

🎯

Training Applications

Use 1RM percentages to design effective training programs. Different percentages target specific adaptations: 50-60% for power, 70% for endurance, 70-80% for hypertrophy, and 80-100% for maximum strength.

⚡

Testing Methods

Direct testing involves progressively increasing weight to failure, while estimation uses submaximal loads. Estimation is safer for beginners and allows more frequent assessment without excessive fatigue.

📈

Progress Tracking

Regular 1RM testing (every 4-8 weeks) helps track strength gains and adjust training loads. Consistent improvement indicates effective programming, while plateaus suggest need for program modifications.

🛡️

Safety Considerations

Always warm up thoroughly, use proper form, and have a spotter when testing near-maximal loads. Beginners should focus on technique development before attempting 1RM testing or heavy percentage work.

Frequently Asked Questions

Everything you need to know about one rep max testing, formulas, and strength training answered by fitness experts.

How accurate are 1RM calculator formulas?

+
1RM formulas are generally accurate within 5-10% of actual maximum when using 1-10 repetitions. Accuracy improves with lower rep counts (1-5 reps). The Epley and Brzycki formulas are most commonly used and validated in research.

What's the best rep range for estimating 1RM?

+
The 1-5 rep range provides the most accurate estimates, with 3-5 reps being optimal for safety and accuracy. Avoid using more than 10 reps as accuracy decreases significantly, and the estimate becomes less reliable for true maximum strength.

Should beginners test their 1RM?

+
Beginners should avoid direct 1RM testing and instead use estimation methods with 5-8 reps. Focus on learning proper form and building base strength for 6-12 months before considering heavy percentage work or maximum testing.

How often should I test my 1RM?

+
Test or estimate 1RM every 4-8 weeks for program adjustments. More frequent testing can interfere with training progress, while less frequent testing may result in using outdated percentages that don't reflect current strength levels.

Which formula should I use?

+
The Epley formula is most widely used and researched. Brzycki works well for 2-10 reps, while Lombardi is good for very low reps. Using the average of all three formulas often provides the most reliable estimate.

Can I use the same 1RM for different exercises?

+
No, 1RM is exercise-specific. Each movement has different muscle recruitment patterns, leverage advantages, and strength requirements. Calculate separate 1RMs for each major exercise in your program.