One-Rep Max Calculator (Epley/Brzycki) implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-235

Effect

Computation or source lookup only

Input and validation requirements

The Brzycki formula has an unhandled division-by-zero input at exactly 37 reps. The calculator must reject reps = 37 rather than emit Infinity, NaN, or an invalid training table. Negative-weight interpretation is also ambiguous unless input validation or an absolute-magnitude convention is specified.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "weight": 100,
    "weight_unit": "kg",
    "reps": 5,
    "formula_choice": "Epley",
    "table_percentage": 0.8,
    "sets": 5,
    "reps_per_set": 5
  },
  "expected_outputs": {
    "estimated_1RM": 116.6666667,
    "estimated_1RM_unit": "kg",
    "table": {
      "scheme": "5x5",
      "percentage": 0.8,
      "load_per_set": 93.3333333,
      "load_unit": "kg"
    }
  },
  "working": "1RM = 100 × (1 + 5/30) = 100 × (1 + 0.1666667) = 100 × 1.1666667 = 116.6666667 kg. Training load = 116.6666667 × 0.80 = 93.3333333 kg per set."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json