One Rep Max Calculator

Features

Your one-rep max (1RM) is the heaviest weight you can lift for a single rep — the most common measure of strength. Enter the weight and reps you actually completed, choose Epley or Brzycki, and get an estimated 1RM instantly. Then map that 1RM to training goals (endurance, hypertrophy, strength, peak power) and see exactly which barbell plates to load on each side. Everything runs locally in your browser; nothing is uploaded.

When You Need This

Common pain points this tool solves

1. You want to know your 1RM without risking a heavy single
2. You finished a 5×5 or 8-12 rep set and want the estimated 1RM equivalent
3. You are following a strength program and need to load 85% or 90% of your max quickly
4. You switched gyms or plate sizes (kg vs lb) and need to rebuild your loads

How to Use

Step-by-step instructions

1. Choose your unit (kg or lb) and enter the weight you lifted.
2. Enter how many reps you completed (1-10 reps gives the most accurate estimate; up to 30 is supported).
3. Pick a formula: Epley is a common all-round choice; Brzycki suits moderate-to-high reps.
4. Read your estimated 1RM, then tap any intensity percentage to send that target weight to the plate calculator.
5. Load the suggested plates on each side; if the exact weight cannot be loaded, the closest achievable load with the difference is shown.

Why Choose Korelyy

What makes us better

1. Two mainstream formulas (Epley / Brzycki) with one-tap comparison
2. Intensity table: 65%-95% mapped to training goals and rep ranges
3. Automatic barbell plate loading for metric and imperial plates
4. 100% local processing — no account, no upload, no tracking
5. Your last inputs are saved locally for the next session

Monetize With This Tool

Turn this tool into a side income stream

1. Use this tool to speed up your freelance work and take on more paying clients
2. Create polished content faster for your blog, YouTube channel, or social media and grow your audience
3. Offer this tool's capabilities as a service on Fiverr, Upwork, or to your local business clients

Frequently Asked Questions

1. What is a one-rep max (1RM)?

   1RM stands for one rep max: the heaviest weight you can lift for one clean rep of an exercise. It is the most widely used measure of strength.

2. What is the difference between Epley and Brzycki?

   Epley: 1RM = weight × (1 + reps/30). Brzycki: 1RM = weight × 36 / (37 − reps). Both estimate from the weight and reps you completed; lower reps give closer results and estimates become less accurate above 10 reps.

3. Why estimate instead of testing a real max?

   Max-effort singles carry injury risk and need full recovery and a spotter. Estimating from a 3-10 rep set is safe and usually within about 5%, which is enough for periodized training.

4. What if the plates cannot load the exact weight?

   When the target is not a multiple of the smallest plate, the tool shows the closest loadable weight and the difference. When in doubt, choose the slightly lighter option to avoid overloading.

5. Is my data uploaded anywhere?

   No. All inputs and calculations stay in your browser locally and are never sent to any server.