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One Rep Max Calculator

Estimate your one-rep max (the maximum weight you can lift once) from the weight and reps you performed, using multiple formulas. Includes a %1RM weight and rep guide table. Runs entirely in your browser.

Last updated: 2026/10/16 Calculator Feedback & bug reports
Lift Data
Please enter a value between 0.1 and 1000
Please enter a value between 1 and 36
Estimated 1RM (Average)
-- kg
Average of multiple formulas.
Estimate by Formula
Epley
-- kg
Brzycki
-- kg
Lander
-- kg
Recommended Weight & Reps by %1RM
%1RM Weight Reps Training Goal
Results are estimates based on formulas and are not medical advice or training instruction. Attempting a true max lift carries injury risk. When lifting heavy, warm up thoroughly and train with a spotter or qualified coach.

How to Use

1

Enter the weight lifted

Enter the weight you actually lifted. Choose kg or lb. For better accuracy, enter a weight you could barely complete.

2

Enter the reps

Enter how many reps you performed with that weight. Fewer reps (about 1-10) give a more accurate estimate.

3

Check your estimated 1RM

As you type, the Epley, Brzycki, and Lander estimates and their average are calculated instantly.

4

Use the %1RM table

Use the table of recommended weights and reps for each %1RM (50-95%) to set loads for your goal (strength, hypertrophy, or endurance).

What is a One Rep Max (1RM)?

A one-rep max (1RM) is the maximum weight you can lift once with proper form. It is widely used as the reference point for setting training intensity. Because attempting a true max lift carries injury risk, this tool estimates your 1RM from reps at a lighter weight using established formulas. All calculations run in your browser; your data is never sent to any server.

Features

  • Multiple Formula EstimationEstimates with three formulas (Epley, Brzycki, Lander) and shows the average for a balanced result.
  • %1RM Guide TableLists recommended weight, reps, and training goal for each %1RM from 50 to 95%, so load setting is instant.
  • Privacy ProtectedAll calculations happen in your browser. Your lift data is never sent to servers.
  • Free, No RegistrationNo sign-up, no install. Works instantly on smartphones and PCs.

Use Cases

  • Estimating 1RM for bench press, squat, and deadlift
  • Choosing optimal weights for strength or hypertrophy
  • Setting program loads as a %1RM
  • Checking a target before attempting a max lift
  • Tracking strength progress over time

FAQ

Which 1RM formulas are used?
Common ones include Epley (1RM = weight x (1 + reps/30)), Brzycki (1RM = weight x 36 / (37 - reps)), and Lander. This tool estimates with all three and shows the average.
How many reps give the most accurate estimate?
Generally, fewer reps (about 1-10) give a more accurate estimate. Above ~10 reps the error tends to grow, so testing at around 5-8 reps is recommended.
What does %1RM mean?
It is the percentage of your 1RM. For example, 80% 1RM means 80% of your max. Strength work uses high intensity (85%+), hypertrophy uses moderate (67-85%), and endurance uses lighter loads (below 67%).
Will the estimate match my real 1RM?
Because it is a formula-based estimate, it will differ from your actual 1RM. Results vary by exercise, experience, and condition. Use it as a guide for setting training intensity.
Is my data safe?
Yes. All calculations run in your browser, and your weight and rep data are never sent to or stored on any server. Note that results are estimates, not medical or professional advice. Always prioritize safety when attempting a max lift.

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Related Guides

What Is 1RM (One-Rep Max)? Formulas, %1RM Chart, and Goal-Based Loading Learn what 1RM (one-rep max) is from the ground up: estimation formulas such as Epley and Brzycki, a %1RM chart showing the relationship between reps and weight, goal-based loading for strength, hypertrophy, and endurance, and how to measure it safely.