One-Rep Max Calculator

Enter a weight you lifted and how many reps you did to estimate the most you could lift once. See seven formulas side by side and a table of training weights at each percentage.

Weight lifted

Reps completed

reps

Whole number from 1 to 20. Most accurate for 10 or fewer.

Reps:

Estimated one-rep max (average of seven formulas)

115.5 kg

The formulas range from 112.5 kg to 119.0 kg for 100 kg × 5 reps.

Epley116.7 kg
Brzycki112.5 kg
Lombardi117.5 kg
Mayhew119.0 kg
O'Conner112.5 kg
Wathan116.6 kg
Lander113.7 kg

Training weights (percent of your 1RM)

Percent	Weight	Typical reps	Focus
100%	115.5 kg	1	Max effort
95%	109.7 kg	2	Strength
90%	103.9 kg	3 to 4	Strength
85%	98.2 kg	5 to 6	Strength
80%	92.4 kg	7 to 8	Strength and size
75%	86.6 kg	9 to 10	Size
70%	80.8 kg	11 to 12	Size
65%	75.1 kg	14 to 16	Endurance
60%	69.3 kg	18 to 20	Endurance

Estimates only: your real max depends on the lift, your technique and your day. Do not test a true one-rep max without a spotter or safety bars, a good warm-up and, if you are new, a coach.

What your one-rep max is

Your one-rep max (1RM) is the heaviest weight you can lift for one repetition of an exercise with good form. Coaches use it to set training weights, because most strength programmes prescribe sets and reps as a percentage of your 1RM. Testing it directly is tiring and risky, so it is usually estimated from a lighter set done for several reps.

The seven formulas

Formula	Estimate of 1RM
Epley	weight × (1 + reps ÷ 30)
Brzycki	weight × 36 ÷ (37 − reps)
Lombardi	weight × reps ^ 0.10
Mayhew	100 × weight ÷ (52.2 + 41.9 × e^(−0.055 × reps))
O'Conner	weight × (1 + 0.025 × reps)
Wathan	100 × weight ÷ (48.8 + 53.8 × e^(−0.075 × reps))
Lander	100 × weight ÷ (101.3 − 2.67123 × reps)

Training percentages

A rough guide to the weights and reps used at different parts of your 1RM. Individuals differ, so treat the reps as approximate.

Percent of 1RM	Typical reps	Focus
100%	1	Max effort
95%	2	Strength
90%	3 to 4	Strength
85%	5 to 6	Strength
80%	7 to 8	Strength and size
75%	9 to 10	Size
70%	11 to 12	Size
65%	14 to 16	Endurance
60%	18 to 20	Endurance

Getting an accurate estimate

Use a set of 3 to 8 reps taken close to failure with strict form. The formulas drift for sets above 10 reps.
Use the same exercise, equipment and range of motion each time.
Estimates are for one lift at a time: your squat, bench press and deadlift each have their own 1RM.
Your max changes daily with sleep, food, stress and fatigue.

Lifting safely

Warm up with lighter sets before heavy work.
Use a spotter or safety bars for squats and bench press.
Build up weight gradually, and consider working with a coach if you are new.
Stop if you feel sharp pain, and talk to a doctor about injuries or health conditions.

How to use the One-Rep Max Calculator tool

Choose kilograms or pounds.
Type the weight you lifted and the number of reps you completed with good form.
Read your estimated one-rep max, the range across the seven formulas and the bars comparing them.
Use the percentage table to pick weights for your sets.

Frequently asked questions

What is a one-rep max?

Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition of an exercise with good form. It is used to set training weights as a percentage of your max.

How is 1RM estimated without testing it?

Formulas such as Epley and Brzycki use the weight you lifted and the number of reps you got. For example, 100 kg for 5 reps gives about 117 kg with the Epley formula (100 × (1 + 5 ÷ 30)).

Which 1RM formula is best?

None is perfect. They agree closely for 2 to 10 reps and drift apart for higher reps, so this calculator shows seven and their average. The estimate is most accurate when you lift close to failure for 10 reps or fewer.

Is it safe to test my true one-rep max?

It carries more risk than lighter sets, because the weight is near your limit. Use a spotter or safety bars, warm up well, and consider using an estimate from a heavier set of 3 to 5 reps instead. New lifters should work with a coach.

How do I use the percentage table?

Strength work is often done at 80% to 95% of your 1RM for fewer reps, and size work at about 65% to 80% for moderate reps. The reps shown are typical, and individuals differ.