Calculators / 1RM calculator / Lying Leg Curl
Lying Leg Curl 1RM calculator
Estimate your lying leg curl one-rep max from any set you completed, see the weight for 1, 3, 5, 8, 10 and 12 reps, and check it against the lift's rep targets. Starting numbers are typical machine loads for this movement — type your own; nothing leaves your browser.
Also called: prone leg curl, hamstring curl
| Reps | % of 1RM | Weight (kg) | |
|---|---|---|---|
| 1 | 100% | 67.5 | |
| 3 | 94.4% | 63.8 | |
| 5 | 88.9% | 60 | |
| 8 | 80.6% | 54.4 | |
| 10 | 75% | 50.6 | |
| 12 | 69.4% | 46.9 |
How the math works
- 1RM = weight × 36 ÷ (37 − reps) — Brzycki, sets of 12 reps or fewer
- 1RM = weight × (1 + reps ÷ 30) — Epley, sets above 12 reps
- rep-max table: weight for N reps = 1RM × (37 − N) ÷ 36 (N ≤ 12), else 1RM ÷ (1 + N ÷ 30)
Worked example: 60 × 36 ÷ (37 − 5) = 60 × 36 ÷ 32 = 67.5 kg. The switch at 12 reps is why a 12-rep and a 13-rep set do not sit on one smooth curve: Brzycki climbs steeply toward 37 reps, Epley grows in a straight line. Both are population fits from low-rep sets — an estimate, not a test.
Lying Leg Curl quick facts
| Primary muscle | Hamstrings |
|---|---|
| Secondary muscles | — |
| Equipment | Machine |
| Type | Isolation |
| Default rest | 60 s |
| Progression step | 2 kg |
| Rep / RIR targets by goal | strength 6–8 @ RIR 2 · hypertrophy 10–15 @ RIR 1 · general 8–12 @ RIR 2 |
Catalog: Zyra Workouts exercise data · targets from the app's program generator (isolation row) · the progression engine steps lying leg curl by 2 kg once a set clears its ceiling (midpoint of the rep range + RIR: 14 reps for the hypertrophy target).
See also: Lying Leg Curl — muscles, targets, alternatives · Lying Leg Curl load chart (% of 1RM)
Frequently asked
What is my lying leg curl 1RM if I lift 60 kg for 5 reps?
About 67.5 kg. Brzycki: 60 × 36 ÷ (37 − 5) = 67.5. A population estimate, not a tested max — different lifters land on different sides of it.
How many reps at 80% of my lying leg curl max?
The inverse of Brzycki puts 80% at 37 − 36 × 0.8 = 8.2, so about 8 reps. For a 67.5 kg max that is 54 kg; the exact 8-rep weight the table shows is 54.4 kg (80.6%). The Lying Leg Curl load chart lists every 5% step.
Which formula does this use?
Brzycki (weight × 36 ÷ (37 − reps)) for sets of 12 reps or fewer, Epley (weight × (1 + reps ÷ 30)) above — the same rule the Zyra Workouts app applies to every logged working set, so the number here matches the app's.
Is this training advice?
No. It is arithmetic on the set you enter. The lying leg curl targets on this page are the app's default rep and RIR ranges by goal, shown as data; which to train, at what load, is a decision for you and your coach. Training guidance, never medical advice.
Other hinge lifts
Guides for Lying Leg Curl
Log the set, keep the estimate
Zyra Workouts estimates 1RM from every logged lying leg curl set with these formulas, and steps the next load by 2 kg when a set clears its target. It is in development and not yet on the App Store.
Zyra is a training and nutrition tracking tool. Nothing on this page is medical advice, a diagnosis, or an individual prescription. The numbers are estimates from published formulas and the apps' own rules — consult a qualified professional for decisions about your health, and a coach for your training.