How to calculate your 1RM?

Calculating your 1RM (your max rep) is one of the simplest hacks to stop training "by feel".

Because once you know your 1RM, you can:

• choose your weights precisely by percentage (for strength, hypertrophy, endurance)

• track your progress correctly

• and most importantly, lift smarter on the movements that matter (squat, bench press, etc.)

In this article, you'll learn a reliable method to estimate your 1RM!

Let’s go 🔥

What's 1RM?

Your 1RM (one-repetition maximum) is the heaviest weight you can lift just once, with good technique and a full range of motion.

The problem?
Many people "calculate" their 1RM using a random formula... based on a set that is not at all representative... and end up with a useless (or even dangerous) number.

Why is it useful?

• it's an objective foundation for calculating your training weights in % of your 1RM

• you can track your progress

• you can plan your cycles better (strength → volume → intensification)

Method 1: Estimating Your 1RM from a Single Set

 

The Simple Method

1. Choose a compound movement (bench press, squat, deadlift, etc.).
   
   

2. Then do one reference set:

   • 3 to 10 reps

   • close to failure (while maintaining good technique)
     
     

3. Calculate using a suitable formula (right after).
   

Formulas to use

You don't need to use many. In practice, 2 are enough:

• Epley: 1RM = weight × (1 + reps/30)

• Brzycki: 1RM = load × 36 / (37 − reps)
  

Which formula should you choose based on your reps?

Full example

You do 8 reps at 80 kg on the bench press, with clean form.

• Epley: 1RM = 80 × (1 + 8/30) = 80 × (1 + 0.2667) = 80 × 1.2667 ≈ 101.3 kg

• Brzycki: 1RM = 80 × 36/(37−8) = 80 × 36/29 = 80 × 1.2414 ≈ 99.3 kg

➡️ So, your "useful" 1RM is ≈ 100 kg (rounded).

And you can plan your loads by percentage.

Method 2: Test your real 1RM

Simple protocol

• General + specific warm-up

• Then several short sets, increasing the weight

• 2-3 serious attempts max (otherwise you'll get tired and underperform)

If you're testing your bench press, don't do it alone without safety catches or a spotter.

At home: having high-quality equipment is essential. A stable setup that can be upgraded to "rack" mode allows you to load heavier with more confidence.

Our freestanding pull-up bar + barbell supports is specifically designed to turn your setup into a more complete home gym (for bench, squats, etc.). 

%1RM: what weights should you use?

Tip: for many people, "classic" muscle growth often happens around 70-80% of their 1RM.

The 8 mistakes that can mess up your 1RM (and how to avoid them)

1. Set not representative (too easy/too far from failure) → aim for a tough, clean set.

2. Changing your technique (bouncing on bench, shortened squat) → stick to the same range of motion, same tempo.

3. Too many reps (15-20+) → use a range, not a single number.

4. Exercise too "isolating" → formulas are more reliable on compound movements.

5. Fatigue / lack of sleep → your "daily" 1RM ≠ your actual strength level.

6. Rushed warm-up → lower performance and high risk.

7. Week-to-week comparison under different conditions → compares similar sets.

8. Wanting a perfect figure → aims for a useful estimate for programming.

FAQ:

Which formula is the most reliable for calculating your 1RM?
For most people, Epley (1-5 reps) and Brzycki (6-10 reps) cover 95% of what you need.

How many reps can I use to estimate my 1RM?
Beyond 10-12 reps, the formulas start to vary a lot more. It's best to stay between 3 and 10 reps.

Why does my 1RM change from day to day?
Sleep, stress, nutrition, warm-up, motivation, and especially: your technique quality. Always compare similar conditions (same exercise, same range of motion...)

How often should you recalculate your 1RM?
It's a good idea to do it at the end of a training block (e.g., every 6 to 12 weeks).

How can I use my 1RM to build muscle?
Aim for your main sets to be around 70-80% of your 1RM, build up your volume, progress with more reps or weight, and keep your form strict. 

I hope you liked this article! 

Feel free to comment and share it if you did! 

See you soon. 

Eric Flag