1RM Lander
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Lander 1RM calculator estimates your maximum weight for a single repetition (1RM) based on the weight used and completed repetitions. This formula is ideal for lifters who want to plan training or compare strength without testing their actual limit. It uses the equation 1RM = (100 × weight) / (101.3 − 2.67123 × repetitions), adjusting the estimate for different rep ranges.
The Lander formula is recommended for multijoint exercises (like squats or bench press) and provides accurate results for sets of 3 to 10 repetitions. For proper use, input the weight lifted and the number of safe repetitions. The result is an approximation that helps structure training plans, such as progressive overload programs or strength goal adjustments.
Remember that the Lander 1RM calculator is an estimate and may not perfectly reflect your actual capacity. Factors like technique, muscle fatigue, and individual variation affect accuracy. Avoid using the result for excessively high weights without professional supervision, as this increases injury risk. Practical tests in controlled environments remain the best reference.
Frequently asked questions
Why use the Lander formula instead of others?
The Lander formula is more accurate for 3 to 10 repetition sets, adapting better to moderate weights in multijoint exercises.
Can I use this calculator for high-repetition sets?
Not recommended. The formula works best for 3 to 10 repetitions. For over 12 repetitions, other formulas may be more suitable.
Is the result 100% reliable?
No. It's an estimate based on average factors. For absolute accuracy, physical 1RM testing in safe environments is needed.
How to use the estimated 1RM in training?
Use it as a base for progressive sets, but adjust according to your body's signals during exercises to avoid overload.