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One Rep Max Calculator

Estimates your 1RM from a submaximal set using Epley, Brzycki and Lombardi formulas, with a full percentage table.

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Enter your figures and press Calculate.
In short One Rep Max Calculator is a free online tool on inputtesthub.com that estimates your 1RM from a submaximal set using Epley, Brzycki and Lombardi formulas, with a full percentage table. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the One Rep Max Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the One Rep Max Calculator

The One Rep Max Calculator estimates your 1RM from a submaximal set using Epley, Brzycki and Lombardi formulas, with a full percentage table. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Programming training percentages without testing a true max.
  • Comparing progress between mesocycles.
  • Setting warm-up jumps.

The maths behind it

This tool uses Epley (w × (1 + reps ÷ 30)), Brzycki (w × 36 ÷ (37 − reps)) and Lombardi (w × reps^0.10), averaged and shown separately. Every intermediate value is shown on screen, so the result can be checked by hand.

Accuracy falls away above about 10 reps, where endurance rather than strength dominates. Use a set of 3-6 reps for the most reliable estimate.

Frequently asked questions

Are there any usage caps on the One Rep Max Calculator?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the utility.
Is my data uploaded anywhere?
No. The One Rep Max Calculator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
Can I check the maths myself?
It uses Epley (w × (1 + reps ÷ 30)), Brzycki (w × 36 ÷ (37 − reps)) and Lombardi (w × reps^0.10), averaged and shown separately. The full working is printed under the result, so you can follow every step rather than trusting a black box.
Who is the One Rep Max Calculator for?
In practice it gets used for three things: programming training percentages without testing a true max. Comparing progress between mesocycles. Setting warm-up jumps. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Is there a catch?
Accuracy falls away above about 10 reps, where endurance rather than strength dominates. Use a set of 3-6 reps for the most reliable estimate.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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