Free · Everyday · Clothing & Sizes

Bra Size Calculator

Estimate a starting band and cup size from snug underbust and full-bust measurements.

  • Checked formula
  • Private in your browser
  • No signup
Calculator inputs

Enter your values

Result

Your calculation

Starting size estimate
32D
US/UK starting point
Sister size down
30DD/E
Sister size up
34C

Sizing differs by brand and bra shape. A fitting and comfort check are more reliable than any formula.

How to use this calculator

  1. Enter the values and choose the units that match your situation.
  2. Calculate to see the primary answer and useful conversions.
  3. Review the assumptions before using the result for a project or decision.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.