In weightlifting, powerlifting, and general strength training, your one-rep max (1RM) is the maximum weight you can lift for a single repetition of a given exercise. Knowing this number is essential for structuring training programs and tracking changes in your muscular strength over time.
Determining your 1RM allows you to customize your training intensity. Most structured strength programs (such as 5/3/1 or block periodization) prescribe workouts using percentages of your 1RM rather than arbitrary weights.
For example, a program might call for 3 sets of 5 repetitions at 80% of your 1RM. To monitor your daily energy and food intake to support these strenuous workouts, check out our daily calorie energy planner. To assess your body fat levels for better relative strength, try our body fat percentage calculator.
Attempting to lift your absolute maximum weight can place significant stress on your muscles, joints, and connective tissues, increasing the risk of injury if your form falters.
Estimating your 1RM using a weight you can lift for multiple repetitions (typically 3 to 10 reps) is a much safer alternative. This calculator uses reliable mathematical formulas (such as the Epley and Brzycki equations) to approximate your max limit based on submaximal performance. To check your baseline resting energy burn, visit our basal metabolic rate planner.
The two most common formulas used to predict 1RM are: - Epley Formula: 1RM = Weight × (1 + (Reps / 30)) - Brzycki Formula: 1RM = Weight / (1.0278 - (0.0278 × Reps))
Both formulas provide very similar results, particularly when the number of repetitions is kept under 10. If reps exceed 10, the accuracy of the prediction begins to decrease. To calculate your target lean body tissue to analyze relative lifting power, see our lean body mass estimator.
Suppose you successfully squat 100 kg (220 lbs) for 5 repetitions.
Using the Epley formula: - 1RM = 100 × (1 + (5 / 30)) - 1RM = 100 × 1.1667 = 116.7 kg.
This indicates your estimated single-repetition squat maximum is roughly 116.7 kg. You can use this figure to establish your workout percentages (e.g. 70% of 1RM would be 81.7 kg). If you want to check if your overall weight aligns with healthy clinical guidelines, use our Body Mass Index classifier or check our healthy weight range finder.
Once you have your 1RM, you can target different muscular adaptations by adjusting the intensity: - Power (1-3 reps): 85% to 95% of 1RM. - Strength (3-6 reps): 80% to 85% of 1RM. - Hypertrophy/Muscle Growth (6-12 reps): 65% to 80% of 1RM. - Endurance (12+ reps): Under 65% of 1RM.
To calculate your total protein and carb needs to support recovery from intense lifting, try our protein calculator and browse our carbohydrate calculator.
Heavy resistance training depletes muscle glycogen and creates micro-tears in muscle fibers. Adequate nutrition and rest are necessary for these tissues to rebuild stronger.
To manage your overall daily macronutrient proportions, check out our macronutrient ratios helper. To estimate calories burned during lifting, see our activity calorie expenditure finder, or try our total daily energy expenditure solver to calculate your active metabolism. For basic calculations, use our everyday daily math helper.