a totally stupid question about measuring for bras

[Phteven]

Zodee has live help so you can chat to them about sizing because it's never consistent across the brands. They also have free delivery on exchanges so if you do end up with the wrong size you can swap it.

ETA - from the Zodee site

Remove clothing before taking measurements but always keep a bra on whilst measuring. A non padded bra gives a more accurate measurement.

and for kicks and giggles

Men Buying For Ladies
The easiest way to determine the size for your ladyfriend is to have a look in her lingerie drawer at the sizes she is currently wearing. This may not always be possible and if the thought of being caught browsing through her lingerie drawer put you off there is another easier method which surprisingly works quite well. Think of her bust as a piece of fruit. The equivalent fruit size matches the cup size you should buy:
Fruit Cup Size
Lemon A Cup
Orange B Cup
Grapefruit C Cup
Melon D Cup