100 kg x 5 reps
- Epley
- 116.67 kg
- Brzycki
- 112.5 kg
- Training range 80%
- 93.33 kg
One Rep Max Calculator
Use this free one rep max calculator to estimate 1RM from a clean rep set with Epley and Brzycki formulas for strength training.
Estimate, not diagnosisFormula notesExample inputsTab-only history
Formula steps
- Use the lifted weight and reps completed.
- Epley estimate = weight x (1 + reps / 30).
- Brzycki gives a second estimate for comparison.
Examples
Recent answers
Recent one-rep max estimates will appear here.
One-rep max formulas are training estimates. Lift safely and use a spotter when needed.
Inputs and recent answers stay in this browser tab and are not sent to a server.
How to use the One Rep Max Calculator
- Enter the requested measurements, dates, lab values, or workout details.
- Check that the units and formula assumptions match what the tool is asking for.
- Press the calculate button to see the answer, supporting metrics, and formula steps.
- Read the estimate with the health disclaimer in mind, then copy the result if you need it for notes.
What people use it for
Estimate a one-rep max without testing a true max.
Compare Epley and Brzycki estimates.
Plan training percentages from a recent rep set.
Track strength changes over time.
Quick examples
Bench example
100 kg x 5Epley about 116.67 kg; Brzycki about 112.5 kg
Squat example
140 kg x 3Epley about 154 kg; Brzycki about 148.24 kg
Volume set
60 kg x 8Epley about 76 kg; Brzycki about 74.48 kg
Deadlift double
180 kg x 2Epley about 192 kg; Brzycki about 185.14 kg
Need the guide or a nearby tool?
Need a slower walkthrough, a related calculator, or the full library? These links keep you close to the task you started.
- How to use the One Rep Max CalculatorSee slower examples, input meanings, formula notes, result limits, and mistakes to avoid.
- Health & FitnessBrowse related calculators and utilities in the same category.
- Calculator and utility guidesFind more guides that use real tool inputs and example numbers.
- All free toolsSearch every live tool, converter, calculator, AI helper, and browser utility.
Frequently asked questions
Plain-language answers about when to use the estimate, what the formula means, what it cannot decide for you, and how privacy works.
When should I use the One Rep Max Calculator?
Use it for simple educational checks, trend tracking, or planning tasks like these: Estimate a one-rep max without testing a true max. Compare Epley and Brzycki estimates. It can help you understand a number, but it cannot explain your whole health situation.
What do the main One Rep Max Calculator inputs mean?
Enter the weight you lifted in kilograms and the number of clean reps you completed. Use a set with full range of motion and consistent form. Do not use failed reps, forced reps, partial reps, or a set above 30 reps as a clean input.
What is the One Rep Max Calculator doing with my inputs?
In plain language: Epley estimate = weight x (1 + reps / 30). Brzycki estimate = weight x 36 / (37 - reps), with the lifted weight used directly for a single rep. The page also shows 80% of the Epley estimate as training-load context. Read the result together with the notes on the page, because health and fitness numbers often need personal context.
How should I read the One Rep Max Calculator result?
Read the Epley estimate as the main training estimate and the Brzycki line as a comparison. If the formulas disagree, treat the gap as uncertainty. Use the number for planning percentages, not as proof that a heavy single is safe today.
Which one-rep max formula should I trust?
Use Epley as the main estimate on this page and Brzycki as a comparison. If they are close, the estimate is more stable. If they are far apart, treat the range as uncertainty instead of chasing one exact number.
Why does the calculator limit reps to 30 or fewer?
Very high-rep sets measure endurance, pacing, and fatigue as much as max strength. The calculator stops at 30 reps so the answer stays in a practical strength-estimate range.
Should I use a failed rep or assisted rep?
No. Use only reps you completed with your own effort and clean form. Failed reps, forced reps, bouncing, shortened range of motion, or uneven technique can inflate the estimate.
What does the 80% training range mean?
It is 80% of the Epley estimate, shown as a planning reference. It is not a required workout weight, beginner program, injury advice, or a guarantee that the load is safe for you.
Why are Epley and Brzycki different?
They are different equations built from the same weight-and-reps idea. The difference reminds you that predicted 1RM is an estimate, especially when reps get higher.
When should I avoid using a one-rep max estimate?
Avoid relying on it by itself if you are injured, new to lifting, returning after time off, lifting without safe equipment, or working under a coach, clinician, or rehab plan with different limits.
Can I use this as medical advice?
This is training math, not a safety guarantee or coaching plan. Do not attempt heavy max lifts without appropriate technique, equipment, warm-up, spotter or safety setup, and supervision when needed. Use the calculator as a learning tool, then ask a qualified professional about decisions that affect care, pregnancy, medication, nutrition, or safety.
What should I double-check before trusting the result?
Check that the weight is in kilograms, the reps were completed with clean form, and the set was not a failure-heavy or assisted set. One accidental unit swap, partial rep, or high-rep endurance set can make the estimate look more precise than it really is.
Does the site save my health inputs?
No. The calculator runs in your browser tab. Recent answers stay only on the page while you use it, and they are not sent to a server.