Bra Calculator

So many women are wearing the wrong size bra, and the high street gives very few options to get measured properly to fit modern bras. This calculator uses our algorithm to offer a starting size to then try bras. Using this, and our fit guides, you can try on bras knowing what should be happening to get your best fit.
Please enter your measurements below to calculate your Boob or Bust recommended Starting Size.
UK Dress size:
Tight : Inches
Snug : Inches
Standing : Inches
Leaning : Inches
Pregnant: No Yes
Breastfeeding: No Yes
Under 18: No Yes
Your Suggested Starting size is
Band Size :

Cup Size :

For a fit check or further information about your suggested starting size, please visit Boob or Bust on Facebook
With clothes and bra off, measure underneath your bust and measure it so tight that you think that the tape might snap. This is your Tight measurement.
With clothes and bra off, measure underneath your bust tightly but still be able to get two fingers under the back. This is your Snug measurement. If you look at two fingers together, that's no more than an inch.
Whilst standing up, measure around the fullest part of your bust (ensuring you don't squash nipples if included, though gently flattening them if very pronounced may be needed), whilst ensuring the tape is level all the way round. This is your Standing measurement.
Lean over so that your boobs are dangling at 90 degrees. Measure around the fullest part again. This is your Leaning measurement.
We adjust our sizing method if you are pregnant to ensure you have space as your body grows.
If your nursling is under 8 weeks, Please contact the Boob or Bust admin via our Facebook page
We adjust our sizing method if you are under 18 to account for a growing body
Disclaimer: The calculator and its coding are the property of Boob or Bust. They may only be reproduced with permission - please contact Boob or Bust via our Facebook page

How To Measure

With clothes and bra off, measure underneath your bust and measure it so tight you think the tape might snap. This is your tight measurement.

With clothes and bra off, measure underneath your bust tightly but still be able to get two fingers under the back. This is your Snug measurement. If you look at two fingers together, that’s no more than an inch.

Whilst standing up, measure around the fullest part of your bust (if this includes your nipples only squash them if they are very pronounced), whilst ensuring the tape is level all the way round. This is your Standing measurement.

Read over so that your boobs are dangling at 90 degrees. Measure around the fullest part again. This is your Leaning measurement.