Butterfly Sticky Bra

Measure your underbust: tape directly under the bust, level all the way round, snug enough for two fingers underneath and no more. Read it breathing out, then round to the nearest even number. That number is your size — there is no cup letter to choose, because the cup is cut to suit the band.

Between two sizes? Take the smaller band in a wired or structured bra, since it loosens with wear. Take the larger in anything wire-free — with no wire holding the shape, a tight band rolls.

Once it is on: fasten a new bra on the loosest hook, and check the band sits level across your back rather than riding up. If your straps are carrying the weight, the band is too loose whatever the label says.