One Rep Max Calculator (1RM Calculator)

They're estimates, not measurements — most accurate at 1–5 reps, less reliable past 10–12 reps where formulas diverge. Comparing several formulas side-by-side gives a realistic range instead of one possibly-misleading number.

No single formula wins for everyone. Epley and Brzycki are the most broadly validated; Brzycki suits bench press, Lander suits heavy deadlifts/squats, Lombardi suits 1–5 reps. This calculator shows all seven so you can see where they agree.

They use regression equations fitted to real lifting data: enter a weight and the reps you managed, and the formula extrapolates your single-rep maximum. Epley, for example, multiplies weight by (1 + reps/30).

Do a heavy set of 2–10 clean reps to near failure, enter the weight and reps above, and pick your lift for context. Brzycki/Epley for bench, Lander for deadlift/squat is the common guidance.

1RM = weight × (1 + reps/30). Example: 100 kg × 5 reps → 116.7 kg. Published 1985; also the equation behind Wendler's 5/3/1 estimation.

1RM = weight × 36/(37 − reps). Example: 100 kg × 8 reps → ≈124.1 kg. Published 1993; identical to Epley at exactly 10 reps.

Jim Wendler's 5/3/1 uses 1RM = weight × reps × 0.0333 + weight — algebraically the same as Epley. This tool's Epley result is your Wendler number.

Each was fitted to different lifters and rep ranges, so they extrapolate differently — especially above 8–10 reps. The spread itself is useful: tight cluster = high confidence.

The formulas have no gender term — they map weight×reps to an estimated max for any lifter. Women use the same equations; validate against your own training data over time.

Strength standards (bodyweight ratios like "1.5× bodyweight squat") vary by source and federation, so this calculator doesn't hard-code any single table as truth. A practical rule: divide your estimated 1RM by your bodyweight — that ratio is what most standard charts are built on. Compare it against the chart you trust, from a source that matches your sex, age and training style.

The standard formulas ignore age, so consider the conservative end of the range (Lander, O'Conner) if you're masters-aged, and youth lifters should only use estimates under qualified supervision, and prioritize technique and safety.

Progressive sets — about 40%×8, 55%×5, 70%×3, 80%×2, 90%×1 — with 2–4 minutes rest between heavy sets. The calculator generates this ladder from your estimated max.

Typical programming: 85–95% for maximal strength, 70–85% for hypertrophy, 60–70% for endurance. The %1RM table converts your max automatically.

Yes — switch to "1RM → reps" mode. Each formula inverts (Wathan and Mayhew can't invert at extreme ratios and show "—" there).

1–5 reps. Sets of 6–10 are still reasonable with Epley/Brzycki; above 10–12, accuracy drops and formulas disagree more.

Any exercise with a known weight and reps: dumbbell bench, dips (bodyweight + added), hip thrust, leg press, curls. Pure bodyweight moves without added load don't fit the formulas.

True max testing is taxing and risky without experience, warmup, a spotter and safeties — which is exactly why estimation from a 3–5 rep set exists. Estimates here are for training guidance, not medical or coaching advice.

Yes — everything runs locally in your browser. No server, no tracking, no account.

Start with the median across all seven, or the conservative Lander estimate. Beginners' true maxes are often technique-limited, so any formula tends to read slightly high — use 90–95% of the estimate for programming.

To find your 1RM without maxing out: warm up thoroughly, then do one heavy set of 3–5 reps, stopping 1–2 reps shy of failure. Enter that weight and rep count above — the seven formulas extrapolate your max from there. No grinder single needed.

It's the reverse direction: enter the hypothetical 1RM you're chasing (a theoretical goal) and see what weights and reps you should be hitting now. Use "1RM → reps" mode above with your target max — the per-formula rep predictions double as milestones.

Yes — take your heaviest successful set of the 5x5 (usually the last set of 5) and enter it. Five reps is squarely in every formula's accurate zone, so 5×5 data converts very reliably.

RPE-based charts exist, but this tool sticks to the seven rep-based formulas because their evidence base is stronger and each equation is directly verifiable. If you track RPE, convert it first: "8 reps @ RPE 9" ≈ an 8-rep set, which you can enter directly.