Four steps. Seven calculators.
Estimate the max from a real set. Translate the max into training percentages. Load the bar. Read the lift-specific caveats before you trust the number. Sources and where published guidance ends sit below each tool.
Estimate the max
Start with a clean submax set you actually did. The general 1RM calculator runs four prediction formulas, averages them, and tells you how much to trust the projection.
Translate the max into training
Once you have a 1RM, the next question is what to put on the bar tomorrow. The percentage calculator turns one number into a training schedule for strength, power, hypertrophy, and peaking.
Load the bar
The last step before a working set is the part everyone fumbles: which plates per side. The plate calculator just answers that question.
Lift-specific caveats
The math doesn't care which lift you did — but the lift cares a lot about technique, equipment, and what the number actually represents. These four calculators reuse the 1RM engine and surface the per-lift gotcha alongside the number.
Squat 1RM calculator
Use this whenYou squatted a heavy set and want a back-squat 1RM estimate with depth, bar position, and belt context.
What it returnsSquat 1RM plus a reliability band and the high-bar vs low-bar, belted vs raw, and parallel vs ATG callouts.
What can mislead youDepth and bar position can swing the number 10–15% at the same 1RM-test effort. A high-bar, parallel-cut squat is not the same lift as a low-bar, just-broke-parallel squat.
Deadlift 1RM calculator
Use this whenYou pulled a heavy set and want a deadlift 1RM estimate, with conventional/sumo and grip caveats.
What it returnsDeadlift 1RM plus a reliability band and the conventional vs sumo, dead-stop vs touch-and-go, and grip-strategy callouts.
What can mislead youTouch-and-go reps and a hook/strapped grip can both inflate the projection beyond what a dead-stop, double-overhand single would actually carry. The estimate is for the rep style you used.
Incline bench 1RM calculator
Use this whenYou want a 1RM estimate for incline press specifically — and a sanity check against your flat bench.
What it returnsIncline 1RM, reliability band, and the typical incline-to-flat ratio range so you can spot lifts that are out of family.
What can mislead youBench angle matters: 30°, 45°, and 60° produce different ratios to flat. The incline:flat band is a population observation, not a conversion factor for your bench.
Dumbbell bench 1RM calculator
Use this whenYour bench day is dumbbell-only and you want to know your dumbbell 1RM, not a guessed barbell equivalent.
What it returnsPer-dumbbell 1RM as the primary output, total external load alongside, and the barbell-equivalent range behind a toggle.
What can mislead youThere is no consensus DB-to-barbell conversion factor. The 1.05–1.25× barbell range is wide on purpose — stability, range of motion, and increment availability all shift the number.
Engines live in lib/strength/and are 100% test-covered. Published formulas — Epley, Brzycki, Lombardi, O'Conner, NSCA percentage bands, ACSM 2026 thresholds — are reproduced from their primary sources and verified against worked examples. Bands and ranges that no peer-reviewed source pins down (1RM reliability ±2/5/10%, the 1.05–1.25× dumbbell-to-barbell range, ExRx-aligned strength-standard multipliers, time-to-next-band speeds) are labelled StrengthMath methodology in-tool. The methodology page details where SM framing fills gaps the literature leaves — and what these calculators do not model (injury, technique, range of motion, equipment, fatigue, coaching).