Estimate your maximum lift by entering the weight and reps you can perform.
in kg
Estimated One Rep Max
114.6 kg
Average of Epley & Brzycki
Epley: 116.7 kg | Brzycki: 112.5 kg
Training Loads by Percentage
100% of 1RM (1 rep)114.6 kg
95% of 1RM (2–3 reps)108.9 kg
90% of 1RM (3–5 reps)103.1 kg
85% of 1RM (6–8 reps)97.4 kg
80% of 1RM (8–10 reps)91.7 kg
70% of 1RM (10–15 reps)80.2 kg
60% of 1RM (15–20 reps)68.8 kg
Based on Epley and Brzycki formulas. Estimates are most accurate for reps 2–10; single-rep or 12-rep estimates may vary.
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What is the One Rep Max Calculator?
Your one rep max (1RM) is the heaviest weight you can lift for one repetition with proper form. It's a key measure of absolute strength used in strength training, powerlifting, and sports performance. Since testing your true 1RM is taxing and injury-prone, coaches and athletes estimate it from a submaximal lift (a weight and rep count you can actually perform) using mathematical formulas. This calculator automates that estimation.
How it works
The calculator takes two inputs: the weight you lifted and the number of reps you performed (1–12). It then applies two widely-used estimation formulas—Epley and Brzycki—each of which adjusts the weight based on rep count to extrapolate a single-rep maximum. Because the two formulas yield slightly different estimates, the tool averages them for a balanced result. It also generates a training-load table showing what weight to use at different intensity percentages (100%, 95%, 90%, etc.) and the rep range best suited to each.
The Epley formula weights the rep count as a percentage of 30, making it slightly more conservative at higher reps. The Brzycki formula uses a ratio of 36 to (37 minus reps), which tends to produce lower estimates, especially above 10 reps. Neither is perfectly accurate for all individuals—strength curve and biomechanics vary—so averaging them gives a more robust estimate. Both formulas become less reliable outside the 2–10 rep range.
Examples
Input
Result
Notes
Weight lifted: 100 kg, Reps: 5
1RM ≈ 114–116 kg
Epley gives ~116 kg, Brzycki gives ~114 kg. This is a reliable estimate in the 5-rep zone. Training at 95% (109 kg) suits 2–3-rep work; 70% (80 kg) suits 10–15 reps.
Weight lifted: 70 kg, Reps: 8
1RM ≈ 88–90 kg
Both formulas agree closely at 8 reps. The average estimate of ~89 kg suggests a 85%-load training weight of ~76 kg for 6–8 rep sets.
Weight lifted: 150 kg, Reps: 3
1RM ≈ 171–174 kg
At lower reps, formulas converge. Estimates are high-confidence. 80% (135 kg) is appropriate for 8–10 rep work; 60% (102 kg) for hypertrophy (15–20 reps).
How to use the One Rep Max Calculator
Enter the weight you can lift for multiple repetitions (in kg or lbs).
Enter the number of reps you performed with that weight (range 1–12).
The calculator instantly applies Epley and Brzycki formulas and averages them.
Read your estimated one rep max in the result box.
Review the training-load table to see recommended weights for different rep ranges and intensity percentages.
Use the 1RM estimate and load table to programme safe, progressive training sessions aligned with your current strength.
Benefits
Avoid injury by estimating 1RM without testing it directly; safer than maxing out in the gym.
Two formulas (Epley & Brzycki) combined give a balanced, reliable estimate rather than relying on a single method.
Instant training-load table simplifies workout programming; immediately see what weight suits your rep target.
Helps coaches and athletes track strength progress over time without constant max attempts.
Free, private, no account or login required; calculation runs in your browser.
Accurate for reps in the 2–10 range; less reliable for singles or 12+ rep estimates.
Tips & common mistakes
Common mistakes
Using a weight you lifted once, not reps you performed cleanly—estimates work best from a weight you can safely repeat.
Assuming the 1RM estimate is your absolute max without testing; it's a statistical estimate, not a guarantee.
Ignoring differences between formulas; Brzycki tends lower at high reps, Epley higher, so averaging is prudent.
Entering reps outside 1–12; the formulas are validated mainly for this range and become unreliable beyond it.
Tips
For most accurate estimates, use a 5–8 rep submaximal test; single reps and 12+ reps are less reliable.
Re-test every 4–8 weeks to track progress and update your training loads as you get stronger.
Use the 1RM to set intensity guidelines (e.g., 80% for strength, 70% for hypertrophy) but adjust based on feel and form.
If two formulas differ widely (e.g., over 15 kg), repeat your submaximal test to confirm before planning heavy sessions.
Remember that form, fatigue, and individual variation affect real maxes; the estimate is a starting point, not gospel.
Frequently asked questions
Why are the Epley and Brzycki estimates different?
Both formulas use different mathematical models to extrapolate from submaximal reps to a single rep. Epley tends to be slightly higher, especially above 10 reps; Brzycki is more conservative. Averaging them balances the approaches and accounts for individual variation in strength curve.
Which rep range gives the most accurate estimate?
Estimates are most reliable for 2–10 reps. At 1 rep, you're already very close to your true max (so estimation is almost unnecessary). At 11–12 reps, both formulas become less accurate because the strength curve flattens and individual variation increases.
Can I use this for machine weights or just barbells?
Yes. The calculator works for any resistance: barbells, dumbbells, machines, or even bodyweight. The key is entering the weight you lifted and the clean reps you completed, regardless of equipment.
My estimated 1RM seems too high (or low). Why?
Estimates depend on form, fatigue, and individual strength curves. If you haven't eaten or slept well, or if you're naturally strong at high reps (or weak at them), the estimate may be off. Re-test on a better day, or adjust your training loads based on how the workout *feels*.
What if I want to estimate from more than 12 reps?
Formulas become unreliable above 12 reps. For very high rep ranges (15+), strength and muscular endurance don't extrapolate cleanly to a single-rep max. Consider testing at 5–8 reps instead, or use a different strength metric (e.g., max reps at 70%).
Is my data safe? Do you store my results?
No. This calculator runs entirely in your browser and does not send, store, or log any data. Your inputs are deleted when you close the page.