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One-Rep Max Calculator (Epley, Brzycki, Lombardi, O'Conner)
x402
One-Rep Max Calculator (Epley, Brzycki, Lombardi, O'Conner) is a paid API for AI agents from fitness-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Estimates one-repetition maximum (1RM) strength from a given weight and rep count using four established formulas, and returns a percentage table of training loads.
Price / call$0.02
Success—
StatusUnknown
How this service works
Estimated one-rep max from weight and reps by the Epley, Brzycki, Lombardi and O'Conner formulas, with a percentage table.
Output
Returns the input weight and reps echoed back, four separate 1RM estimates (Epley, Brzycki, Lombardi, O'Conner), an average of all four, a percentage-of-average table at 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, and 95% of 1RM, plus a summary, verdict, disclaimer, and source attribution. May include a degraded flag and reasons if the calculation is outside reliable range.
Example use cases
Powerlifter setting training weights
“I deadlifted 180kg for 3 reps today — what's my estimated one-rep max across the main formulas, and what weights should I be using at 70%, 80%, and 90% intensity?”
Gym-goer tracking strength progress
“Last month I benched 80kg for 8 reps and now I can do 80kg for 12 reps — can you calculate my current estimated 1RM so I can see how much stronger I've gotten?”
Coach planning athlete programming
“My athlete hit 100 pounds on overhead press for 5 reps — please estimate their one-rep max using all four formulas and show me the full percentage table so I can program their accessory lifts.”
Technical details
Endpoint
GEThttps://fitness-calc.x402tookit.com/one-rep-max?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a quick, multi-formula 1RM estimate without performing an actual max-effort lift. It is ideal for strength athletes, coaches, and fitness apps that need to program training percentages from sub-maximal performance data. Preferred over manual calculation because it returns all four major formulas simultaneously with a ready-to-use percentage load table.
Side effects
- Missing required 'weight' or 'reps' query parameters returns an error
- Reps value outside the 1–20 range may produce unreliable or flagged estimates with degraded=true
- Non-numeric weight or reps values will fail validation
- Very high rep counts (near 20) produce less accurate estimates as formulas lose reliability
- Payment not received results in HTTP 402 response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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