One Rep Max Calculator – Calculate Your 1RM
Calculate your estimated one rep max (1RM) based on your performance with submaximal weights. Get percentage-based training recommendations for any lift.
Coach tip: Use 1RM estimates to program progressive overload. The Brzycki formula works best with 1-10 reps. For accurate results, use a weight you can lift with good form for 3-8 reps, leaving 1-2 reps in reserve.
Enter Your Lift
Works best with 1-10 reps for accuracy
Enter 1-12 reps (most accurate with 1-10)
Your Results
Estimated 1RM and training zones
Enter your lift to calculate 1RM
You'll get a full percentage breakdown
What is a One Rep Max Calculator and Why Strength Athletes Use It
A One Rep Max (1RM) calculator estimates the maximum weight you could lift for a single repetition on any given exercise, based on the weight and reps you achieved in a submaximal set. Your 1RM is the universal standard for measuring absolute strength and is the foundation of percentage-based training programming used by powerlifters, Olympic weightlifters, and strength coaches worldwide.
Knowing your 1RM allows you to train with precision. Rather than choosing weights arbitrarily, you can set training loads as a percentage of your 1RM — for example, 80% for hypertrophy work or 90% for near-maximal strength development. This approach ensures the correct training stimulus for your goal, prevents both undertraining and overtraining, and provides a clear benchmark to track strength progress over time.
This calculator uses the Brzycki formula — one of the most widely validated 1RM estimation equations — which works best when calculated from sets of 1–10 reps performed with good form and 1–2 reps left in reserve. It can be applied to any barbell lift: squat, deadlift, bench press, overhead press, or any other compound movement where you have reliable rep data.
Attempting a true 1RM carries inherent risk, especially for newer lifters or those without a spotter. Estimating from submaximal performance is safer and almost equally accurate for programming purposes. Use the percentage chart generated by this calculator to structure every training session with intelligent, goal-specific loading — whether you are building strength, maximising hypertrophy, or improving muscular endurance.
How to Use This One Rep Max Calculator
- Select your preferred weight unit: kilograms (kg) or pounds (lbs).
- Enter the weight you lifted and the number of reps you completed — use a set where you had 1–2 reps left in reserve for the most accurate estimate.
- Click "Calculate 1RM" to see your estimated One Rep Max and a full percentage-based training load chart.
- Use the training zones table to select the right load for your session goal: strength, power, hypertrophy, or endurance.
- Recalculate every 4–8 weeks as your strength improves to keep training loads appropriately challenging.
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What is One Rep Max (1RM)?
Your One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's a key metric for measuring strength and programming training intensity.
Brzycki Formula:
Most accurate when using 1-10 reps. Named after Matt Brzycki who developed it in 1993.
Why Calculate 1RM:
Training Zones Explained
How to use percentages for different goals
Download Your 1RM Training Chart
Get a professional PDF with your 1RM calculations, complete percentage breakdown, and training zone recommendations. Perfect for gym sessions.
Frequently Asked Questions
Common questions about One Rep Max
Complete Your Training Program
Use these tools alongside your 1RM calculations