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One-Rep Max Calculator

Estimate your 1RM from any lift and see your full percentage table.

  • 🧮 Calculator
  • ✓ Free
  • ✓ No sign-up
  • ✓ Private — runs in your browser
  • ✓ Any device
🏆 Best 1RM:

Tip: estimates are most accurate at 1–10 reps. High reps reduce accuracy.

Why you’ll love One-Rep Max Calculator

Instant & freeNo signup, no paywall, no limits — One-Rep Max Calculator works the moment the page loads.
Completely privateEverything runs in your browser. Nothing you enter is ever uploaded or stored on a server.
Works on any deviceFully responsive and touch-friendly — use it on your phone, tablet or desktop.
Accurate & clearBuilt on the real formulas, with a breakdown you can actually trust.

How to use it

  1. 01

    Open it

    No download and no login — the tool is ready right at the top of this page.

  2. 02

    Use it

    Enter your details or start interacting. Everything updates live as you go.

  3. 03

    Get your result

    Copy, download or share your result in a single tap. That’s it.

About One-Rep Max Calculator

A one-rep max calculator estimates the maximum weight you can lift for a single repetition (1RM) based on the weight and reps you can currently perform. It uses established strength training formulas to predict your 1RM from any lift—whether it's a barbell squat, bench press, deadlift, or dumbbell exercise. This free browser tool requires no signup and makes strength testing faster and safer.

Once you enter your lift, the calculator displays your estimated 1RM and generates a complete percentage table showing what weight you should use for different rep ranges. This percentage-based breakdown is useful for programming workouts, scaling exercises, and tracking progress over time. The tool runs entirely in your browser—your data never leaves your device.

Whether you're new to strength training and want to estimate your starting weight, or a seasoned lifter planning a training cycle, this 1RM strength calculator removes the guesswork. It helps you train at the right intensity without testing your actual one-rep max, which is time-consuming and carries higher injury risk.

Popular uses

  • ✦ Plan a periodized strength training program without testing your actual one-rep max.
  • ✦ Scale gym exercises to the right weight for your target rep range—5 reps for strength, 8-12 for muscle gain.
  • ✦ Track strength progress over weeks by re-testing a familiar lift and watching your 1RM estimate climb.
  • ✦ Quick pre-workout reference to know what weight to load for a specific rep target.
  • ✦ Help beginners estimate a safe starting weight without years of training experience.

Frequently asked questions

How accurate is a one-rep max calculator?
One-rep max calculators use proven strength training formulas (like Epley or Brzycki) that work well for most lifters in the intermediate range. The estimate is usually within 5-10% of your actual 1RM. Accuracy improves with consistent training history; beginners or elite lifters may see wider variation.
What weight and reps should I use?
Use a weight you can perform for 2-10 clean reps with good form. Avoid testing when fatigued. The calculator is most reliable when you stay in this rep range—testing with 1 rep or 15+ reps reduces accuracy. Pick a recent actual lift you know, not your best guess.
Why does the percentage table matter?
The percentage table shows the weight you should lift for different rep ranges based on your estimated 1RM. For example, 85% of your 1RM is typically right for 3-5 reps. Programs use these percentages to safely scale exercises and maintain correct intensity for your training goals.
Can I use this for any exercise?
Yes, the 1RM calculator works for any lift—barbells, dumbbells, machines, or bodyweight. The math is the same regardless of exercise. For pure bodyweight exercises, estimate your bodyweight as the load.
Is One-Rep Max Calculator free to use?
One-Rep Max Calculator is 100% free — no signup, no watermarks and no usage limits. It’s one of 200+ free tools we build and give away.
How accurate is this calculator?
It uses the standard formulas and shows its working, so you can verify every number. For big decisions, treat the result as a reliable estimate.

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