How is Lander different from Brzycki?

Only in the constants. Both are of the form 100 × weight ÷ (a − b × reps). Lander uses 101.3 and 2.67123; Brzycki's equivalent constants are 102.78 and 2.78. The outputs differ by around a percent at most in the usable range.

Why does it break at high reps?

As reps rise, the term 2.67123 × reps approaches 101.3, the denominator approaches zero, and the estimate explodes — then goes negative once reps exceed about 38. It is only valid well below that; treat it as a 1-to-10-rep formula.

Which should I use day to day?

If you already think in Brzycki, keep using it. Lander is worth knowing because some strength texts and spreadsheets default to it, and seeing both confirms your estimate is not an artefact of one equation.

Good for the deadlift?

It works, but the deadlift usually permits fewer reps per percentage than the bench, so keep the input set at 5 reps or fewer for the deadlift specifically.

Should I round the result?

Yes — round to the nearest 2.5 kg (or 5 lb), the smallest plate jump most gyms allow. A 1RM estimate to the tenth of a kilo is false precision.

Lander 1RM Calculator — One Rep Max Estimate

Training loads from your estimated 1RM
% of 1RM	Load	Typical reps
100%	—	1
95%	—	2
90%	—	3–4
85%	—	5–6
80%	—	7–8
75%	—	9–10
70%	—	11–12

The Lander formula

1RM = 100w ÷ (101.3 − 2.67123 · reps), where w is the weight lifted and reps the number completed. Best suited to ≤ 10 reps.

Worked example

Bench 100 kg for 10 reps. Lander: (100 × 100) ÷ (101.3 − 2.67123 × 10) = 10000 ÷ 74.59 = 134.1 kg. For 100 kg × 5: 10000 ÷ (101.3 − 13.36) = 113.7 kg.

How it compares

Lander and Brzycki agree within about 1% across 1 to 10 reps — pick whichever you find easier to remember. Both are pure low-rep tools: Lander's denominator hits zero near 38 reps, so this calculator blocks rep counts that push it negative. Above 10 reps, move to Wathan or Mayhew.

Which formula for which rep range

Formula	Best for
Brzycki	≤ 10 reps
Lombardi	any rep count, conservative
O'Conner	low reps; understates at high reps
Wathan	wide range, good at 10+ reps
Lander	≤ 10 reps
Mayhew	bench press, 10+ reps
Epley	1–10 reps

Rule of thumb: Brzycki, Lander and O'Conner for sets of 10 reps or fewer; Wathan and Mayhew when the set ran longer; Lombardi as a conservative all-rounder. The safest input is a hard set of 3 to 6 reps, where every formula nearly agrees.

The other 1RM formulas

Epley formula — the default, and the parent calculator.
Brzycki — 1RM = weight × 36 ÷ (37 − reps). The other standard; the most accurate of the set at low reps.
Lombardi — 1RM = weight × reps^0.10. A power curve rather than a straight line — stays sane at high reps.
O'Conner — 1RM = weight × (1 + 0.025 × reps). The gentlest estimate — 2.5% added per rep.
Wathan — 1RM = 100w ÷ (48.8 + 53.8 × e^(−0.075 × reps)). An exponential fit that holds up well at higher reps.
Mayhew — 1RM = 100w ÷ (52.2 + 41.9 × e^(−0.055 × reps)). Derived from bench-press data; a solid pick for higher reps.

Using the number

Once you have a 1RM, programmes prescribe work as a percentage of it — use the table above the fold to plan a session. Feed your bodyweight and goal into the calorie calculator and macro calculator to support the training, and see progressive overload for adding weight over time.

Source: Lander, 1985; see Wikipedia, "One-repetition maximum".

Last reviewed: September 2026. Figures and formulas are checked against their published sources; see the site's data notes.

Lander One Rep Max Calculator

The Lander formula

Worked example

How it compares

Which formula for which rep range

The other 1RM formulas

Using the number

Related calculators

Related guides

Frequently asked questions