How do you calculate your one rep max?

Take a set to near failure in the 1–10 rep range, then apply Epley: weight × (1 + reps ÷ 30). 80 kg for 8 reps is 80 × 1.267 = 101 kg. Brzycki's formula, weight × 36 ÷ (37 − reps), gives 80 × 36 ÷ 29 = 99 kg. Enter the set above and both figures appear.

What percentage of 1RM should I lift for 5 reps, 8 reps or 10 reps?

By Epley, 5 reps at about 86%, 8 reps at 79% and 10 reps at 75% of your max — the table under the result lists 1 to 12 reps with the load in kg or lb. Programmes that quote 87%, 80% and 75% are using a rounded version of the same curve.

Which is more accurate, Epley or Brzycki?

They are close between 5 and 10 reps and both are averages with a few percent of error for an individual. Epley tends to estimate higher at low reps and Brzycki higher at high reps. Pick one, use the same one every time, and treat the number as a planning figure rather than a target to attempt cold.

Is it safe to test a one rep max?

Safer to estimate, which is what this page is for. If you do test, warm up thoroughly, use a spotter or safety pins, take small jumps from about 90% of the estimate, and stop at the first rep that breaks form. Beginners rarely need a tested max at all.

One Rep Max Calculator (Epley & Brzycki, with % of 1RM Table)

Estimated one-rep max from a set of 1–12 reps, by Epley or Brzycki, with training loads at each rep count.

Inputs

Weight lifted(kg)

1 kg500 kg

Reps completed

112

Formula

Units

Include CalculateEveryday mark

Estimated 1RM

116.7 kg

Training loads from a 116.7 kg max (Epley (1985))

Reps	% of 1RM	Load (kg)
1	97%	112.9
2	94%	109.4
3	91%	106.1
4	88%	102.9
5	86%	100.0
6	83%	97.2
8	79%	92.1
10	75%	87.5
12	71%	83.3

Working: 100 × (1 + 5 ÷ 30) = 100 × 1.167 = 116.7 kg
Set used: 100 kg × 5 reps (Epley (1985))
Brzycki (1993) gives: 112.5 kg
Your set as % of 1RM: 86%

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What each One Rep Max input means

Weight lifted: The weight you lifted for the set, in kg or lb, bar included.
Reps completed: Clean reps completed with that weight, 1 to 12. The estimates are most reliable at 10 or fewer.
Formula: Epley (1985) or Brzycki (1993). They agree at 10 reps; below that Epley reads a little higher.
Units: Metric (km, kg) or US units (miles, pounds). The weight lifted converts between kilograms and pounds when you switch.

One Rep Max formula

Epley: 1RM = weight × (1 + reps ÷ 30) · Brzycki: 1RM = weight × 36 ÷ (37 − reps) · Load for n reps = 1RM ÷ (1 + n ÷ 30) (Epley)

\text{1RM}_{\text{Epley}} = w\left(1 + \frac{r}{30}\right) \qquad \text{1RM}_{\text{Brzycki}} = \frac{36w}{37 - r}

A one-rep max is the most weight you could lift once. Testing it directly is risky and tiring, so coaches estimate it from a set of several reps taken to or near failure. Epley's formula adds one-thirtieth of the weight for every rep: 100 kg for 5 reps is 100 × (1 + 5 ÷ 30) = 116.7 kg. Brzycki's divides 36 by (37 − reps) instead and gives 112.5 for the same set; the two agree at about 10 reps and drift apart below and above, with Epley higher for low reps. Both are fitted to bench press and squat data on trained lifters and are only meant for 1 to 12 reps — a 20-rep set says little about a max. Run backwards, the same formula gives the load for any rep target, which is the table under the result: the percentages most programmes quote (5 reps at about 87%, 10 at 75%) come straight from it.

One Rep Max worked example

100 kg for 5 clean reps, by Epley: 1 + 5 ÷ 30 = 1.167, so the estimated max is 116.7 kg — the set was 86% of it. Brzycki puts the same set at 100 × 36 ÷ 32 = 112.5 kg. From the 116.7 kg Epley max, 3 reps would be 106.1 kg (91%), 8 reps 92.1 kg (79%) and 10 reps 87.5 kg (75%).

More One Rep Max examples

60 kg for 10 reps, by Brzycki: 60 × 36 ÷ 27 = 80.0 kg — and Epley gives the same, since the two formulas meet at 10 reps.

225 lb for a triple, by Epley: 225 × 1.1 = 247.5 lb. Brzycki says 238.2 lb, so the true single is likely somewhere around 240 lb.

Where the One Rep Max calculator can give the wrong answer

The estimate is only as good as the set. Reps stopped two short of failure, a bounced bench press or a shallow squat all push the number up; a set on tired legs pushes it down. Use a fresh, honest set of 3–6 reps for the tightest estimate.
Above about 10 reps the formulas diverge and both lose accuracy, because endurance starts to matter more than strength. Sets over 12 reps are refused for that reason.
The formulas were fitted on barbell bench press and squat. They run high on isolation lifts and machines and are not meant for Olympic lifts, where technique caps the reps.
An estimated max is not a tested one. Before loading a bar to the figure here, work up in small jumps with a spotter or safety bars; the estimate can be 5–10% out either way.
Kilograms and pounds behave the same because both formulas only multiply the weight — no conversion happens, the unit label just follows your choice.

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One Rep Max reference table

A set's weight as a share of the one-rep max, by reps
Reps	Epley	Brzycki
2	93.8%	97.2%
3	90.9%	94.4%
4	88.2%	91.7%
5	85.7%	88.9%
6	83.3%	86.1%
8	78.9%	80.6%
10	75%	75%
12	71.4%	69.4%

Source: Epley: 1 ÷ (1 + reps ÷ 30); Brzycki: (37 − reps) ÷ 36 — the two published formulas this page uses

One Rep Max FAQ

: Take a set to near failure in the 1–10 rep range, then apply Epley: weight × (1 + reps ÷ 30). 80 kg for 8 reps is 80 × 1.267 = 101 kg. Brzycki's formula, weight × 36 ÷ (37 − reps), gives 80 × 36 ÷ 29 = 99 kg. Enter the set above and both figures appear.
: By Epley, 5 reps at about 86%, 8 reps at 79% and 10 reps at 75% of your max — the table under the result lists 1 to 12 reps with the load in kg or lb. Programmes that quote 87%, 80% and 75% are using a rounded version of the same curve.
: They are close between 5 and 10 reps and both are averages with a few percent of error for an individual. Epley tends to estimate higher at low reps and Brzycki higher at high reps. Pick one, use the same one every time, and treat the number as a planning figure rather than a target to attempt cold.
: Safer to estimate, which is what this page is for. If you do test, warm up thoroughly, use a spotter or safety pins, take small jumps from about 90% of the estimate, and stop at the first rep that breaks form. Beginners rarely need a tested max at all.