Estimate your one-rep max (1RM) from any weight and rep count, plus a full training percentage chart.
| % of 1RM | 90% | 80% | 70% | 60% | 50% |
|---|---|---|---|---|---|
| Weight | — | — | — | — | — |
This calculator uses the Epley formula, one of the most common ways to estimate a true one-rep max without actually testing a single maximal lift, which carries injury risk when done without proper preparation.
Most strength programs prescribe work at a percentage of your 1RM rather than an absolute weight, since it scales automatically as you get stronger. Lower percentages (50-70%) are typically used for warm-ups, technique work, or higher-rep volume sets, while 80-90%+ is used for strength-focused, lower-rep training.
Estimating 1RM from a submaximal set is generally safer than testing a true single-rep max, but any heavy lifting should still be done with a spotter or safety equipment where appropriate, and with a warm-up. If you're new to a lift, prioritize form over chasing a higher estimated number.
Enter the weight you lifted and the number of repetitions you completed with good form. Click Calculate, and the tool estimates your one-rep max along with a full percentage chart showing suggested weights for various training percentages. Use a set where you reached, or came close to, muscular failure for the most accurate estimate — a set with several reps left in reserve will tend to underestimate your actual capacity.
Testing an actual one-rep max means attempting a single lift at the absolute heaviest weight you can manage, which carries meaningfully higher injury risk than working within a submaximal rep range, particularly for lifters without a spotter, without ideal form, or without extensive experience under heavy loads. Estimating 1RM from a lighter, higher-rep set — typically in the 3 to 8 rep range for best accuracy — provides a useful approximation without the same level of risk, which is why most strength coaches recommend estimation over frequent max-effort testing for regular training purposes.
The Epley formula, developed by Boyd Epley, calculates estimated 1RM as: weight × (1 + reps ÷ 30). For example, lifting 200 lbs for 5 reps gives an estimated 1RM of 200 × (1 + 5/30) = 200 × 1.167 ≈ 233 lbs. This formula tends to work reasonably well for moderate rep ranges (roughly 2-10 reps), but becomes progressively less reliable at higher rep counts, since the relationship between reps and strength isn't perfectly linear — fatigue and endurance factors start to play a bigger role the longer a set goes, which the simple formula doesn't fully capture.
The Epley formula is widely used, but it's not the only one — the Brzycki formula, another common option, calculates 1RM as weight ÷ (1.0278 − 0.0278 × reps), and tends to produce slightly different estimates, particularly at higher rep counts. Different formulas were developed using different populations and rep ranges, which is part of why two calculators can occasionally give slightly different 1RM estimates for the same input. In practice, these differences are usually small enough not to matter for everyday training purposes, and consistency in which formula you use over time matters more than which specific one you pick.
Once you have an estimated 1RM, training programs typically prescribe work at specific percentages depending on the goal. Percentages in the 85-100% range build maximal strength but require low reps (1-3) and longer rest periods due to the high intensity. The 70-85% range is commonly used for hypertrophy (muscle growth) work, typically in the 6-12 rep range. Below 70% is generally used for technique refinement, warm-up sets, or higher-volume endurance-focused training. Because your true strength naturally improves or declines over time with training, periodically retesting or re-estimating your 1RM keeps percentage-based programming accurate rather than working off an outdated number.
Which rep range gives the most accurate 1RM estimate? Generally 3 to 8 reps taken close to failure provides the most reliable estimate — very low rep sets (1-2) are close to a true max already, while very high rep sets (12+) tend to be less accurate due to fatigue effects the formula doesn't fully account for.
Should beginners use 1RM percentages for programming? Beginners can use estimated 1RM for reference, but many coaches recommend prioritizing consistent technique development over strict percentage-based programming in the early stages of training.
How often should I retest or re-estimate my 1RM? Every 4-8 weeks is common for actively training lifters, since strength changes meaningfully over that timeframe with consistent training, keeping percentage-based programming aligned with your current capability.
Does this formula work the same for all lifts? It's most commonly applied to major compound lifts like squat, bench press, and deadlift. Estimation accuracy can vary more for smaller isolation movements, where technique and stabilizer muscle fatigue play a larger relative role.
Is the Epley formula the only method for estimating 1RM? No — other formulas like Brzycki and Lander exist and can produce slightly different estimates for the same weight and rep count, though they generally agree within a small margin for moderate rep ranges.
Can this calculator be used for bodyweight exercises like pull-ups? It's designed around external weight and reps, so it works best for barbell and dumbbell lifts rather than bodyweight movements where added resistance isn't straightforward to quantify.
Why do 1RM estimates matter for injury prevention? Training off an accurate percentage of your estimated max, rather than guessing at an appropriate weight, helps avoid both undertraining (too light to build strength) and overtraining with poor form at weights beyond current capability.
Does bodyweight affect 1RM estimation accuracy? The formula itself doesn't factor in bodyweight directly, though lifters with a higher strength-to-bodyweight ratio may find estimates from higher rep ranges slightly less precise than those closer to their actual max effort.
Can I use this calculator for training programs based on percentages, like 5/3/1? Yes — estimate your 1RM here, then apply whatever percentage scheme your program calls for based on that number.
Last reviewed by Mehmed on July 11, 2026.