1RM & Barbell Plate Calculator

What is a 1RM Calculator?

1RM (One Repetition Maximum) is the maximum weight you can lift for one repetition. Direct testing carries injury risk, so we use the Epley formula for safe estimation: 1RM = Weight × (1 + Reps/30). The formula is most accurate in the 6–10 rep range. This tool returns your input weight unchanged when reps = 1, shows an accuracy warning at 12+ reps, and blocks input above 15 reps to prevent unrealistic estimates (e.g., 30 reps → 2× weight). Plate loading is visualized with IWF standard colors, and when greedy plate combinations cannot exactly match the target weight, the difference is explicitly shown so users are not misled.

Common Use Cases

How to Use

1. 1
   Enter weight and reps

   Input the weight (kg) and reps from your recent set (1–15 recommended). 12+ reps lose accuracy.
2. 2
   Check calculated 1RM

   View your estimated 1RM via the Epley formula. A single-rep entry returns your input weight as-is.
3. 3
   Select barbell weight

   Choose whether you're using a 20kg Olympic bar or 15kg women's bar.
4. 4
   Enter target & view plates

   Input your desired total weight to see IWF-standard colored plates. If the greedy combo cannot match exactly, the difference from your target is shown.

Frequently Asked Questions