One Rep Max and Strength Standards Calculator

Work out how strong a lift is, from every angle, in one run. Give it a weight and rep count and it estimates your one rep max seven different ways. Give it a bodyweight and a lift and it tells you where you sit on the strength ladder. It also scores powerlifting totals, loads the bar, and writes your warmup.

Everything is pure offline math. No API key, no login, no scraping, nothing that can go stale. The same input always returns the same numbers.

What it does

Send a list of calculations. Each one is an object with a type and its own fields. You can mix types in a single run, and one bad row returns an error instead of stopping the others. Output is one row per calculation, with a primary headline and the full numeric detail.

Six calculation types:

• one-rep-max estimates your 1RM from a weight lifted for a given number of reps. Returns Epley, Brzycki, Lombardi, O'Conner, Wathan, Lander and Mayhew side by side, their average, and a percentage-of-1RM load table from 1 to 12 reps.
• rep-max-table takes a known 1RM and projects the load for 1 to 12 reps, both by the standard training percentages and by the Epley model. Optional roundTo snaps to your smallest plate jump.
• strength-standards classifies a lift as beginner, novice, intermediate, advanced or elite using bodyweight ratios, and shows the weight needed for each level and the next one to chase. Built-in standards for bench, squat, deadlift and overhead press, or supply your own four ratios.
• wilks-dots scores a total (or a single lift) with Wilks, Wilks 2, DOTS and IPF GL points, so you can compare lifters across bodyweights. Works in kg or lb.
• plate-loading works out which plates to hang per side to hit a target weight, from the standard plate set or your own. Tells you the exact loaded weight and any leftover.
• warmup builds a ramp of warmup sets up to a working weight, with reps per set and optional plate rounding.

Input

{
  "calculations": [
    { "type": "one-rep-max", "weight": 100, "reps": 5, "unit": "kg" },
    { "type": "strength-standards", "lift": "squat", "sex": "female", "bodyweight": 65, "oneRepMax": 100, "unit": "kg" },
    { "type": "wilks-dots", "sex": "male", "bodyweight": 90, "total": 600, "unit": "kg" },
    { "type": "plate-loading", "targetWeight": 142.5, "unit": "kg" }
  ]
}

Fields by type:

• one-rep-max: weight, reps, unit
• rep-max-table: oneRepMax, unit, optional roundTo
• strength-standards: lift, sex, bodyweight, oneRepMax, unit, optional ratios (a list of four bodyweight multiples for novice, intermediate, advanced, elite)
• wilks-dots: sex, bodyweight, total, unit
• plate-loading: targetWeight, unit, optional barWeight, optional availablePlates (a list of plate sizes)
• warmup: workingWeight, unit, optional workingReps, optional barWeight, optional roundTo

unit is kg or lb. sex is male or female. Every type accepts an optional label that is echoed back on the row.

Leave the input empty and it runs six prefilled examples, one of each type.

Output

One row per calculation. Common fields are calculationType, label, primary, input, unit, ok and error. Type-specific fields fill in the rest, for example estimated1RM and the seven formula estimates for one-rep-max, level and ratio for strength-standards, wilks, dots and ipfGL for wilks-dots, and platesPerSide with achievableWeight for plate-loading. Nested tables like percentTable, repMaxTable and warmupSets carry the full detail.

The Overview table view shows the headline columns. Switch to the full JSON to see the nested tables.

Notes on the numbers

The 1RM formulas are estimates and agree best at 10 reps or fewer. Above that the row is flagged with lower accuracy. Strength standards are general bodyweight-ratio guidelines for adult raw lifters, not medical or competition thresholds, so treat them as a rough map rather than a verdict. Wilks and DOTS use the published coefficient sets and IPF GL uses the 2020 classic raw constants.

This is a training tool, not medical advice. Warm up properly and lift within your limits.