1RM from 100 kg for 5 reps

Q: If I lift 100 kg for 5 reps, what is my 1RM?

100 kg for 5 reps gives an estimated 1RM of 116.7 kg with Epley. Brzycki gives slightly less. The two barely differ at 5 reps, so the figure is fairly reliable.

Q: Do I need to test my real 1RM?

100 kg for 5 reps gives an estimated 1RM of 116.7 kg with Epley. Not for programming. Training off percentages of this estimate and repeating the 5-rep set every few weeks is enough.

By Jesús Narváez Tamés · Published on October 28, 2026

Worked example with Epley and Brzycki: what you would lift for one rep if you move 100 kg five times, and which loads to use at 90, 80 and 70%.

116.7kg

Brzycki: 112.5 kg

Weight lifted: 100 kg
Reps: 5
Formula: Epley
90% of 1RM: 105.0 kg
80% of 1RM: 93.3 kg
70% of 1RM: 81.7 kg

Five reps at 100 kg is a very common set on any main lift, and the next question is always the same: what would that be for one? The figure above comes from Epley, the calculator's default formula, with Brzycki underneath for comparison.

The estimate holds if those five reps were genuinely close to failure. If you had two or three left in the tank, your real 1RM is higher. Use it to set the loads for your working sets, not as a max to test every week.

How this was calculated

Epley: 1RM = weight × (1 + reps / 30). It is an estimate, reliable up to about 10 reps taken close to failure. Brzycki (weight × 36 / (37 − reps)) is shown for contrast: if the two drift apart, the set had more reps than the formula handles well.

Nearby values

The same calculation changing only the weight. The highlighted row is this example.

Weight	Result
90 kg	105.0 kg	Brzycki: 101.3 kg
95 kg	110.8 kg	Brzycki: 106.9 kg
100 kg	116.7 kg	Brzycki: 112.5 kg
105 kg	122.5 kg	Brzycki: 118.1 kg
110 kg	128.3 kg	Brzycki: 123.8 kg

Adjust it to your numbers

The calculator starts from this example. If you change a field, that value is saved only on this device.

Units

Weight lifted (lb)

Reps performed

Formula

Estimated 1RM

257.2lb

Percentage table

1 reps
100 %
257.2 lb
2 reps
95 %
241.1 lb
3 reps
92 %
233.8 lb
4 reps
89 %
226.9 lb
5 reps
86 %
220.5 lb
6 reps
83 %
214.3 lb
8 reps
78 %
203.1 lb
10 reps
75 %
192.9 lb
12 reps
70 %
183.7 lb

Max (1-2 reps) (≥90%) Strength (3-5 reps) (80-89%) Hypertrophy (6-12 reps) (70-79%) Volume (60-69%) Endurance (<60%)

Open the calculator without this example

Disclaimer: this calculator provides educational information and estimates based on standard formulas. It is not a substitute for personalised advice from a doctor, nutritionist or trainer. Consult a professional before making significant changes to your diet or training.

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Frequently asked questions

If I lift 100 kg for 5 reps, what is my 1RM?+

100 kg for 5 reps gives an estimated 1RM of 116.7 kg with Epley. Brzycki gives slightly less. The two barely differ at 5 reps, so the figure is fairly reliable.

Do I need to test my real 1RM?+

100 kg for 5 reps gives an estimated 1RM of 116.7 kg with Epley. Not for programming. Training off percentages of this estimate and repeating the 5-rep set every few weeks is enough.

Worked examples

A specific profile, with the number already done. Open it if it looks like you, then adjust.