BiteCheck calculators
1RM Calculator
Estimate your one-rep max using four trusted strength formulas and map training percentages for common rep ranges.
Lift details
Use the heaviest set you can complete with good form.
How the 1RM calculator works
Instead of testing a true max in the gym, the calculator projects your 1RM using a weight you can lift for multiple reps. It compares four of the most widely cited formulas and averages them to provide a balanced estimate. This gives you a practical training number without the fatigue or risk of a maximal attempt.
The formulas we use
- Epley: Best known for linear progressions and classic strength programs.
- Brzycki: Common in powerlifting circles for submaximal sets.
- Lander: Research-based and similar in behavior to Brzycki.
- Lombardi: Uses an exponential curve to temper higher-rep estimates.
Using %1RM to plan workouts
Once you have an estimated 1RM, use the percentage table to choose weights for different rep ranges. For example, a set of 5 reps often lands around 85–87% of your max. Pair the table with your training goal: higher percentages for strength, lower percentages for volume and hypertrophy work.
Tips for a better estimate
- Choose a recent top set where form was solid and tempo was controlled.
- Stay within 1–10 reps for the most accurate projection.
- Use consistent units, warm up thoroughly, and avoid estimating when you are overly fatigued.
- Recalculate every 4–6 weeks as your strength improves.
FAQ
What is a one-rep max (1RM)?
Your 1RM is the maximum weight you can lift for a single repetition with good form. Calculators estimate it from a submaximal set.
Which 1RM formula is most accurate?
No single formula is perfect. We show four common equations and average them to smooth out differences.
How many reps should I use for the estimate?
The formulas are most reliable for sets of 1–10 reps. Higher-rep sets can overestimate your true max.
Do I need to test a true 1RM?
Not necessarily. Use the estimate to plan training loads, then adjust based on how the weights feel in the gym.
Does the unit (kg or lb) matter?
No. The formulas work the same way in any unit as long as you stay consistent.
Can I use this for any lift?
Yes. The calculator works for squats, deadlifts, bench press, or any exercise where weight and reps are known.
Informational only, not medical advice. Consult a healthcare professional for personalized guidance.
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