1RM Leg Curl Calculator
The Leg Curl 1RM Calculator helps you estimate the maximum weight you can curl on a leg curl machine for one repetition. Instead of testing your true one rep max (which can strain your hamstrings and joints), this calculator uses your submaximal lifts (weight + reps) to give you a safe and accurate estimate. After you calculate, our AI Personalized Coach will provide training tips to improve hamstring strength and reduce injury risk.
How to Use the Leg Curl 1RM Calculator
Enter the weight you lifted on the leg curl machine.
Enter the number of repetitions you performed.
Hit “Calculate” to get your estimated 1RM.
Review insights and tips from your AI Coach in the results area.
Why Use a Leg Curl 1RM Calculator?
- Track hamstring progress: Monitor strength gains over time.
- Stay safe: Avoid overloading your hamstrings with risky max attempts.
- Plan workouts better: Set training zones for hypertrophy, endurance, or strength.
- Balance your legs: Compare hamstring strength (leg curl) with quadriceps strength (leg extension, squats).
Leg Curl vs Deadlift Strength Ratio
How strong should my leg curl be compared to my deadlift?
Most lifters can leg curl about 30-40% of their deadlift 1RM. For example, if your deadlift max is 150 kg, your leg curl 1RM will likely fall in the 45-60 kg range.
The deadlift is much stronger because it uses multiple muscle groups (legs, back, core, grip), while the leg curl isolates the hamstrings. If your curl is below 30% of your deadlift, it may signal weak hamstrings and higher injury risk.
So, keep your leg curls progressing alongside compound lifts. Strong hamstrings protect your knees, improve sprinting speed, and help prevent injuries.
Safety Tips for Heavy Leg Curls
- Warm up before loading heavy weights.
- Avoid jerking the weight and control both up and down phases.
- Don’t arch your lower back off the bench.
- Stop if you feel sharp hamstring pain.
- Use full range of motion, but don’t hyperextend.