Keep the tape firm and level, right under the bust, over a thin or unpadded bra.
Enter your underbust measurement to continue.
Why the band comes first
A bra's band, not its straps, is designed to carry roughly 80% of the garment's support. Get the band right and the cups mostly take care of themselves; get it wrong and no cup size will feel comfortable for long.
No padding, no "add four inches" — just your rounded underbust number. If that number lands on an odd figure, we round up to the nearest even size, since that's what's actually sold on shelves.
Getting it right
Signs your band size is off
Band rides up your back
If the back of the band climbs upward during the day, even on the tightest hook, size down.
Red marks or digging
Visible marks after a few hours, or a band you can't loosen further, means it's time to size up.
Level and on the loosest hook
A correct band sits parallel to the floor and fastens comfortably on the loosest of its hooks when new.
Move in a hook, don't resize
As elastic naturally relaxes, tighten the hook before assuming you need an entirely different band.
Questions
Band size FAQs
Yes, using the modern direct-measurement method — round your underbust to the nearest whole number and that becomes your band, with no extra inches added.
The band carries the majority of a bra's support. A correct band keeps the cups sitting where they should; a wrong band undermines even a well-fitted cup.
Most retail bands are sold in even numbers, so we round to the nearest even figure to match what's actually on shelves.
No — band and cup are independent. Any band size can pair with any cup letter depending on your own measurements.
It can, though usually more slowly than cup size — weight change, posture, and even rib structure shifts can move the band number over months or years.
Also useful