1RM Calculator
Calculate your 1RM.
Calculate your 1RM.
Whether you're a beginner or an experienced lifter, knowing your one-rep max (1RM), the maximum amount of weight you can lift for a single repetition, is key to tracking progress and setting training goals. A strength calculator helps you estimate this number safely, without needing to max out in the gym every time.
This article will walk you through what a strength calculator does, how to use it, the formulas behind it, and how to apply the results to optimize your workouts.
A strength calculator estimates your 1-rep max (1RM) based on the number of reps and weight you've already lifted. Instead of attempting a potentially risky max-effort lift, you can use this tool to estimate your maximum lifting capacity across common exercises like the bench press, squat, and deadlift.
This calculation is especially useful for:
Understanding your 1RM helps you design a training plan that suits your goals. Here's why it matters:
A strength calculator uses known reps and weights to estimate your 1RM. Different formulas exist, but the most commonly used ones include:
Each formula provides slightly different results depending on your rep range, so using more than one can help you find a consistent estimate.
You did 100 kg for five reps on the bench press. Using the Epley Formula:
1RM = 100 × (1 + 5 ÷ 30) = 100 × (1 + 0.167) = 100 × 1.167 = ~116.7 kg
So, your estimated 1-rep max is about 117 kg.
Once you know your 1RM, you can apply it to create personalized workout percentages:
| Training Focus | % of 1RM | Reps per Set | Goal |
|---|---|---|---|
| Power | 90–100% | 1–3 | Max strength |
| Strength | 80–90% | 3–6 | Build strength |
| Hypertrophy | 65–80% | 6–12 | Muscle growth |
| Endurance | 50–65% | 12+ | Muscle endurance |
Use these percentages to guide your weight selection based on your training goals.
To get the most accurate results from your strength calculator:
If you're using compound lifts like squats, deadlifts, or presses, ensure you're fully warmed up and using consistent technique.
As you get stronger, your 1RM will increase, so you should periodically update your estimate.
You can also test different lifts individually to spot imbalances or plateaus in your training.
A strength calculator is a practical tool to estimate your 1RM and help guide your lifting journey, without the risks of maxing out. Whether your goal is to build strength, gain muscle, or improve endurance, understanding your lifting potential allows you to train smarter and progress faster.
Instead of guessing what weights to use, let a strength calculator help you train purposefully.