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?
First, make sure you measured correctly. Measure topless (a bra or even a shirt can mess with the measurements). Pull the tape snug for underbust. Lean forward and let your breasts hang fully when measuring leaning bust. If you are not sure about RELAXED FIT or FIRM FIT, start with FIRM FIT if you want any level of lift.
If the calculator is still giving you a size that puts you in disbelief, we encourage you to give it a try. You could order your current size along with the new size – returns are free. If your shoulder straps fall off, you get spillage, the bra band isn't staying down… we have an inkling that the new size will make a difference. Visible spillage (anything more than a smidge) means at least 2 cup sizes too small. If the bra band is riding up, it's at least 1 band size too big.
The most popular sizes at Understance are 36DDD and 34G. Many of our customers switched from 38C to 36DDD, 46DD to 42K, 34D to 30G… When a bra fits well, your breasts are not smooshed by the cups. They are contained, separated, and lifted.
All size calculators are approximations, but our calculator is off by one size or less 80%+ of the time. If you've visited a store that carries a full size range, tried on several neighboring sizes, and found your best size, stick with that size. However, if you bought your current bra at a big box store that only carries A-DD, then definitely give the new size a try – and see if it unlocks a new world of comfort.
If the calculator is still giving you a size that puts you in disbelief, we encourage you to give it a try. You could order your current size along with the new size – returns are free. If your shoulder straps fall off, you get spillage, the bra band isn't staying down… we have an inkling that the new size will make a difference. Visible spillage (anything more than a smidge) means at least 2 cup sizes too small. If the bra band is riding up, it's at least 1 band size too big.
The most popular sizes at Understance are 36DDD and 34G. Many of our customers switched from 38C to 36DDD, 46DD to 42K, 34D to 30G… When a bra fits well, your breasts are not smooshed by the cups. They are contained, separated, and lifted.
All size calculators are approximations, but our calculator is off by one size or less 80%+ of the time. If you've visited a store that carries a full size range, tried on several neighboring sizes, and found your best size, stick with that size. However, if you bought your current bra at a big box store that only carries A-DD, then definitely give the new size a try – and see if it unlocks a new world of comfort.
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.
Our size calculator measures your underband differently. Loose underband and tight underband can differ by 4’’ or more. Instead of taking an average of the two, we ask that you measure your underband as tightly as you'd like your bra to fit. If you are familiar with size calculators that take loose, snug, and tight measurements, our measurement will be closest to "snug."
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.
Our size calculator measures your underband differently. Loose underband and tight underband can differ by 4’’ or more. Instead of taking an average of the two, we ask that you measure your underband as tightly as you'd like your bra to fit. If you are familiar with size calculators that take loose, snug, and tight measurements, our measurement will be closest to "snug."
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 |
