One Rep Max Calculator
Enter the weight you lifted and how many reps you completed to estimate your 1RM, then compare to strength standards.
Estimated 1 Rep Max
Training Percentages
| Reps | % of 1RM | Weight | Zone |
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Rep Range Guide
How to Estimate Your One Rep Max
Your one rep max (1RM) is the cornerstone of percentage-based strength programming. Nearly every evidence-based training programme - from 5/3/1 to Texas Method to Bulgarian Method - prescribes loads as a percentage of your 1RM. Without knowing this number, you are guessing at intensity rather than training it precisely.
The safest way to find your 1RM is to work up to a challenging set of 3–6 reps and enter that weight and rep count here. The Epley and Brzycki formulas will estimate your maximum from that sub-maximal effort. Both formulas are accurate for sets of 2–10 reps performed close to technical failure; accuracy decreases for sets above 10 reps because individual fatigue profiles vary too much. Use the average of both formulas, or take the lower number for conservative programming.
This calculator covers all 64 exercises in the LiftCodex database. After calculating your 1RM, you can compare it to strength standards for your bodyweight and gender. The exercise-specific standards account for the fact that different movement patterns produce different relative strengths - the average person squats significantly more than they bench press, and bench presses more than they overhead press, even at similar training ages.
Frequently Asked Questions
What is a one rep max (1RM)?
Your one rep max is the maximum weight you can lift for exactly one complete repetition with good form. It is the gold standard measure of absolute strength and is used to set training loads as percentages of 1RM.
How do I estimate my 1RM without actually maxing out?
Perform a set with a weight you can lift 2–10 times close to failure, then enter the weight and rep count into this calculator. It uses the Epley and Brzycki formulas to estimate your true maximum from that sub-maximal effort.
Which formula should I use - Epley or Brzycki?
Both are well-validated. Epley (weight × (1 + reps/30)) is slightly more common and generous at higher rep counts. Brzycki (weight × 36/(37−reps)) is more conservative. For programming purposes, use the average or pick the lower number for safety.
How often should I test my 1RM?
True 1RM testing is taxing and carries injury risk. Most lifters test every 8–16 weeks at the end of a training cycle. Using a calculator from a hard set of 3–5 is a safer and more frequent alternative.
What are training zones and how do I use them?
Training zones group rep ranges by adaptation: Max Strength (1–3 reps, 90–100% 1RM), Strength (4–6 reps, 85–90%), Hypertrophy (8–12 reps, 67–80%), and Endurance (15+ reps, below 65%). Structure your program around the zone that matches your goal.
Why does my strength level only show when I enter bodyweight?
Strength levels are measured relative to bodyweight - a 100 kg squat means something very different for a 60 kg lifter versus a 120 kg lifter. Providing your bodyweight lets the calculator normalise your lift and place you in the correct bracket.