How to Use This 1RM Calculator

1. Select your preferred Units (Pounds or Kilograms)
2. Enter the Weight Lifted for a specific exercise (e.g., bench press, squat, deadlift)
3. Enter the Reps Performed (1-10 reps — most accurate range)
4. Select Rounding Preference — Standard (nearest 5 lb/2.5 kg) or Exact
5. View your Estimated 1RM and Warm-Up Set Guide (50%, 70%, 90% of 1RM)

How 1RM is Calculated (Brzycki Formula)

1RM = Weight Lifted × 36 ÷ (37 − Reps Performed)

The Brzycki formula is one of the most accurate for estimating one-rep max from submaximal lifts. Best results with 1-10 reps.

Real Example

Inputs:

• Units: Pounds (lb)
• Weight Lifted: 225 lb
• Reps Performed: 5 reps
• Rounding: Standard (nearest 5 lb)

Calculation: 225 × 36 ÷ (37 − 5) = 225 × 36 ÷ 32 = 253.125 lb

Results:

• Estimated 1RM: 255 lb (rounded to nearest 5 lb)
• Warm-Up Sets:
  – Set 1 (50%): 125 lb × 5-8 reps | Rest 1-2 min
  – Set 2 (70%): 175 lb × 3-5 reps | Rest 2-3 min
  – Set 3 (90%): 230 lb × 1-2 reps | Rest 3-4 min

Why Use This 1RM Calculator?

• ✅ Scientifically Validated — Uses Brzycki formula, proven in strength research
• ✅ Warm-Up Plan Included — Instant warm-up sets at 50%, 70%, and 90% of your 1RM
• ✅ Safe Estimation — No need to attempt a risky maximal lift
• ✅ Units & Rounding Options — Pounds/Kilograms, standard or exact rounding
• ✅ Works for Any Exercise — Bench press, squat, deadlift, overhead press, pull-ups, etc.
• ✅ Free & Unlimited — No signup required
• ✅ Mobile Friendly — Responsive design for phones, tablets, and desktops

Frequently Asked Questions

How accurate is the Brzycki 1RM formula?

The Brzycki formula is most accurate for 1-10 reps (typically within 5-10% of actual 1RM). For 10+ reps, accuracy decreases. For best results, test with a weight you can lift for 3-8 reps.

Can I use this calculator for any exercise?

Yes — works for bench press, squat, deadlift, overhead press, pull-ups, dips, rows, and any barbell/dumbbell exercise. Always use proper form and a spotter.

What’s the difference between standard and exact rounding?

Standard rounding: Rounds to nearest 5 lb (or 2.5 kg) — practical for gym plates.
Exact rounding: Shows the raw calculated number without rounding.

Why is this better than testing my actual 1RM?

Testing actual 1RM requires maximal effort and carries injury risk, especially for beginners. This calculator gives a safe, accurate estimate using submaximal weights you can lift for multiple reps.

How often should I test my 1RM?

Re-test every 4-8 weeks to track strength progress. Use the same formula consistently. A 5-10% increase in estimated 1RM indicates meaningful strength gain.

Related Fitness Calculators

• Calorie Burn Calculator — Estimate calories burned during exercise
• BMR Calculator — Basal metabolic rate
• Macro Nutrient Calculator — Plan protein, carbs, and fats
• BMI Calculator — Body Mass Index

Disclaimer: This 1RM calculator provides estimates for informational purposes only. Actual strength varies based on fatigue, technique, and individual factors. Always use a spotter and proper form when lifting heavy. Consult a fitness professional before starting any new training program.