Free 1RM Calculator

What Is a Free 1RM Calculator?

A 1RM (one-rep max) calculator estimates the heaviest weight you can lift for one repetition of a given exercise. Instead of actually attempting a dangerous maximal lift, you perform a set of 3-10 reps and the calculator extrapolates your max using the Epley formula: 1RM = Weight x (1 + Reps / 30). This is the safest way to determine your strength ceiling for bench press, squat, deadlift, or any barbell movement.

How to Use the Free 1RM Calculator

1. Perform a working set: Do a set of 3-10 reps with a challenging but manageable weight. Use strict form — no bouncing, no partial reps. The accuracy improves with sets of 3-5 reps.
2. Enter the weight lifted: Type the exact weight you used for the set in pounds or kilograms.
3. Enter the reps completed: Type the number of full, clean repetitions you completed before failure or form breakdown.
4. Read your estimated 1RM and percentage chart: The calculator returns your estimated max and a percentage breakdown (50%-100%) for programming sets at specific intensities.

Who Is This For?

• Strength athletes following percentage-based programs (like 5/3/1 or Starting Strength) who need accurate training weights for each session.
• Personal trainers writing programs for clients who need to set appropriate weights without making clients attempt dangerous maximal lifts.
• Recreational lifters tracking strength progress over time who want a consistent, safe way to benchmark performance without maxing out.

Key Benefits

• 100% private — your lifting numbers stay on your device.
• Uses the Epley formula — the industry-standard 1RM estimation method.
• Free, no account — check your max anytime without logging into an app.
• Includes percentage chart — instantly see weights for 50%, 60%, 70%, 80%, 90%, and 95% of your max.

Common Use Cases

Programming training weights: Your program calls for 5 sets of 3 at 85% of your 1RM. Enter your last set of 5 at 225 lbs, get your estimated max of 263 lbs, then see that 85% is approximately 224 lbs.

Tracking strength over time: Last month you did 185 x 8 (estimated max: 231 lbs). This month you did 195 x 7 (estimated max: 241 lbs). Your strength increased by about 10 lbs without ever testing a true max.

Setting competition goals: You want to hit a 315 lb deadlift in competition. If you can pull 275 for 5 reps, your estimated max is 319 — you are likely ready.

1RM Formulas Explained

Most 1RM calculators use a single formula. This tool uses the Epley formula as the primary estimate:

Epley: 1RM = Weight × (1 + Reps ÷ 30)

A commonly compared alternative is the Brzycki formula:

Brzycki: 1RM = Weight × (36 ÷ (37 − Reps))

Both formulas produce similar results in the 3–8 rep range. Brzycki tends to be slightly more conservative and is preferred by some powerlifting coaches. Epley slightly overestimates at higher rep ranges (10+ reps). For most lifters doing sets of 3–6, either formula gives a reliable training max.

Exercise-Specific Notes

Bench Press: Most accurate for 1RM estimation. Use 3–5 rep sets for best accuracy.

Squat: Accurate with strict form. Avoid estimating from high-rep sets (8+) as fatigue skews results.

Deadlift: Use sets of 3–5 only. Grip and lower back fatigue affect accuracy at higher reps.

Overhead Press: Works well. Rep maxes tend to be lower relative to 1RM, so Epley is reliable here.

Frequently Asked Questions