Bra Size Calculator
For the most accurate results, measure without a bra or shirt on.
Note: Results are in U.S. cup sizes.
Frequently Asked Questions
The size you suggested is very different from my usual size. My current bra isn't that bad. Is there a mistake?
We encourage you to give our size calculator's recommendation a try, even if it's different from what you're used to. Our calculator is 80% accurate within one size.
If you're struggling with slipping straps, spillage, or the bra band isn't staying down, it's likely time for a new size—and we're confident it will make all the difference.
Many of our customers have gone from 38C to 36DDD, 46DD to 42K, or 34D to 30G. When your bra fits well, your breasts are comfortably lifted, separated, and contained without being squished.
Give our calculator recommendation a try, risk-free. Returns are on us!
If you're struggling with slipping straps, spillage, or the bra band isn't staying down, it's likely time for a new size—and we're confident it will make all the difference.
Many of our customers have gone from 38C to 36DDD, 46DD to 42K, or 34D to 30G. When your bra fits well, your breasts are comfortably lifted, separated, and contained without being squished.
Give our calculator recommendation a try, risk-free. Returns are on us!
Which sizing method does your calculator use?
Our calculator uses "plus 0" and "plus 2", depending on your preference for a firm or relaxed fit.
If you prefer a firm and supportive fit, prioritizing shoulder relief and separation, you will get your "plus 0" size. It will be a smaller band size, and a larger cup size.
If you prefer a loose and relaxed fit, prioritizing ribcage comfort and keeping the natural breast shape, you will get your "plus 2" size. It will be a larger band size, and a smaller cup size.
If you prefer a firm and supportive fit, prioritizing shoulder relief and separation, you will get your "plus 0" size. It will be a smaller band size, and a larger cup size.
If you prefer a loose and relaxed fit, prioritizing ribcage comfort and keeping the natural breast shape, you will get your "plus 2" size. It will be a larger band size, and a smaller cup size.
How tight should I measure my underband?
Measure tighter if: your bra band tends to ride up in the back and gets pushed down in front (the “seesaw effect”), the straps are too far apart and cut into your armpit, or you prefer a firm fit.
Measure looser if: you have ribcage sensitivities, you have a more muscular body type, you only want nipple coverage with minimal support, or you prefer a relaxed fit.
Measure looser if: you have ribcage sensitivities, you have a more muscular body type, you only want nipple coverage with minimal support, or you prefer a relaxed fit.
How do you know if your bra fits?
We recommend checking the following for the right fit:
1. The bra band should stay put without being uncomfortably tight. It should be parallel to the floor, not riding up in the back.
2. Shoulder straps shouldn’t dig in, slip off, or cut into your armpits.
3. Your breasts should be contained in the cups without overflow or gaps.
4. The underwire should contour your breasts without poking anywhere.
5. Generally, the center gore should lie flat against your chest. However, if your breasts are touching when supported (there is no room for the center gore between your breasts), you are wearing a wireless bra with no center gore, or you have an inverted sternum, the center gore doesn’t need to lie flat against your chest.
Remember to do the "scoop and swoop" (reaching into the bra cups and scooping all the breast tissue into them). Do this every time you put a bra on.
1. The bra band should stay put without being uncomfortably tight. It should be parallel to the floor, not riding up in the back.
2. Shoulder straps shouldn’t dig in, slip off, or cut into your armpits.
3. Your breasts should be contained in the cups without overflow or gaps.
4. The underwire should contour your breasts without poking anywhere.
5. Generally, the center gore should lie flat against your chest. However, if your breasts are touching when supported (there is no room for the center gore between your breasts), you are wearing a wireless bra with no center gore, or you have an inverted sternum, the center gore doesn’t need to lie flat against your chest.
Remember to do the "scoop and swoop" (reaching into the bra cups and scooping all the breast tissue into them). Do this every time you put a bra on.
What sizing system do you use?
Understance uses U.S. sizing. If you are more familiar with U.K. sizing, here’s a side-by-side comparison of cup sizes:
| U.S. CUP SIZE | U.K. CUP SIZE |
|---|---|
| A | A |
| B | B |
| C | C |
| D | D |
| DD (E) | DD |
| DDD (F) | E |
| G | F |
| H | FF |
| I | G |
| J | GG |
| K | H |
| L | HH |
| M | J |
| N | JJ |
