Enter Your Lift Data
Choose exercise, enter weight and reps you can perform with good form
Your 1RM Results
Enter your lift data to see your estimated one rep max with training percentages and strength analysis
Your Estimated 1RM
Training Percentages
| % | Weight | Reps | Purpose |
|---|
Rep Range vs Weight
Common Questions
What is 1RM and why calculate it?
Your one-rep max (1RM) is the maximum weight you can lift once with proper form. It's used to set training percentages (60-95% of max) for different goals like strength, hypertrophy, or endurance.
Is it safe to test my actual 1RM?
Testing true 1RM requires spotters and proper warm-up. This calculator is safer—use your 3-5 rep max for accurate estimates without the injury risk of maximal attempts.
How accurate is the Epley formula?
Epley is most accurate for 1-10 reps and used by powerlifters worldwide. For best results, test with 3-5 reps. Higher reps (10+) reduce accuracy slightly but still provide useful training guidance.
How do I use these percentages?
Use 80-85% for strength (4-6 reps), 70-80% for hypertrophy (8-12 reps), 60-70% for endurance (12+ reps). Start lower if you're a beginner and always prioritize proper form over weight.
How the 1RM Calculator Works
Understanding one rep max estimation formulas
The Epley Formula
Our calculator uses the Epley formula: 1RM = weight × (1 + reps/30). This equation, developed by Dr. Boyd Epley in 1985, is considered the most accurate for estimating one rep max from sets of 1-10 repetitions.
The formula works because there's a predictable relationship between the weight you can lift for multiple reps and your absolute maximum. Each additional rep represents roughly 2.5-3% less than your true 1RM.
Accuracy by Rep Range:
- • 1-5 reps: ±2-3% accuracy (most reliable)
- • 6-10 reps: ±5-8% accuracy (still good)
- • 11-15 reps: ±10-15% accuracy (less reliable)
- • 15+ reps: Not recommended (high error)
Why 1RM Matters for Training
Knowing your 1RM allows you to program training intensity precisely. Instead of guessing weights, you can calculate exact percentages: 85% for strength, 75% for hypertrophy, 65% for endurance work.
Proper percentage-based training ensures you're working at the optimal intensity for your goal. Too light and you won't stimulate adaptation. Too heavy and you risk injury or poor form.
Training Percentage Guide:
- • 90-100%: Max strength (1-3 reps)
- • 80-90%: Strength building (3-6 reps)
- • 70-80%: Hypertrophy (6-12 reps)
- • 60-70%: Endurance (12-20 reps)
When to Use the 1RM Calculator
Best practices for safe and accurate estimation
Starting a New Program
Before beginning percentage-based programs, establish your baseline 1RM for accurate weight selection across all training phases.
Avoiding Max Attempts
True 1RM testing carries injury risk. Estimation from 3-5 rep sets is safer while providing reliable programming data.
Progress Tracking
Test every 4-6 weeks to measure strength gains and adjust training weights for continued progression.
Proper 1RM Estimation Protocol
Best Practices:
- • Warm up thoroughly (10-15 minutes)
- • Use 3-5 reps for most accurate results
- • Choose a weight that causes failure at target reps
- • Maintain perfect form throughout the set
- • Rest 3-5 minutes before testing
- • Test when fresh (early in workout)
Avoid These Mistakes:
- • Testing when fatigued from prior work
- • Using more than 10 reps (inaccurate)
- • Reps not taken close to failure
- • Poor form or momentum used
- • Testing true 1RM without experience
- • Retesting more than once per month
Continue Your Fitness Assessment
Complete your profile with these complementary tools
Calculate your TDEE (daily calories) to fuel your strength gains, track BMI and body fat percentage alongside your lifting progress.