1RM (One-Rep Max) Calculator
Calculate your one-rep max (1RM) – the maximum amount of weight you can lift in a single repetition. This tool uses multiple formulas to give accurate estimates based on your input.
Estimated One-Rep Max (1RM)
Other Calculators in This Category
What is a 1RM (One-Rep Max) and Why It Matters?
Your 1RM (One-Rep Max) is the maximum amount of weight you can lift for a single repetition of a specific exercise. It’s a gold-standard measure in strength training and resistance workouts. Whether you're lifting for power, building muscle, or tracking gym progress, knowing your 1RM helps you:
- ✅ Set accurate workout intensity levels
- ✅ Choose the right weight for your goals (endurance, hypertrophy, strength)
- ✅ Monitor strength progression over time
How to Calculate Your One-Rep Max
Our One Rep Max Calculator estimates your 1RM based on the weight lifted and the number of repetitions completed. It uses science-backed formulas including:
- Epley Formula: Best for 1–10 reps
- Brzycki Formula: Accurate up to 10 reps
- Lombardi Formula: Includes reps with exponential weight influence
- O’Conner Formula: Ideal for strength + endurance
Use the 1RM Percentage Chart to Plan Your Training
After calculating your 1RM, you can use our 1 rep max percentage chart to determine how much weight to lift for specific goals:
- 60–70% of 1RM: Muscle endurance & toning
- 70–80% of 1RM: Muscle growth (hypertrophy)
- 80–90% of 1RM: Strength development
- 90–95% of 1RM: Max strength & power
Why Use Our 1RM Calculator?
This free and accurate 1 rep max calculator is perfect for athletes, bodybuilders, powerlifters, personal trainers, and beginners alike. It supports both kg and lbs, and provides:
- ✔ Instant multi-formula 1RM estimates
- ✔ Personalized percentage breakdowns
- ✔ Easy-to-read layout for quick gym reference
Tips for Getting an Accurate 1RM Estimate
- Perform the test after a proper warm-up
- Use compound lifts like squats, deadlifts, or bench press
- Don’t exceed 10 reps when estimating — the lower, the more accurate
- Rest 2–3 minutes between sets
- Stay safe: use a spotter and avoid max testing without supervision
Frequently Asked Questions (FAQs) – One-Rep Max Calculator
1. What is a 1RM (One-Rep Max)?
A 1RM, or One-Rep Max, is the maximum amount of weight you can lift for one complete repetition of an exercise with proper form. It helps assess your strength and set training intensities.
2. Why should I calculate my 1RM?
Knowing your 1RM allows you to personalize your workouts by setting accurate loads for endurance, hypertrophy, or strength goals. It also helps track progress over time.
3. Which 1RM formula is the most accurate?
Each formula works well in different scenarios. Epley and Brzycki are most popular for up to 10 reps. For more reps or advanced users, Lombardi and O’Conner may give better estimates.
4. Can I use this 1RM calculator for any exercise?
Yes! You can use it for bench press, squats, deadlifts, overhead press, and other major compound movements. Just enter the weight and reps you performed.
5. Is it safe to test my actual 1RM?
Testing your real 1RM can be risky if you're new to lifting. Use this calculator instead. If you test it in the gym, make sure to warm up properly, use a spotter, and avoid lifting to failure without supervision.
6. What units does the 1RM calculator support?
This tool works with both kilograms (kg) and pounds (lbs). Simply select your preferred unit and enter your values.
7. How accurate is a rep-based 1RM calculator?
Rep-based formulas are very accurate up to around 10 reps. Beyond that, estimations become less reliable due to muscular endurance playing a bigger role than raw strength.
Try our free online 1 rep max calculator now and take your gym performance to the next level.