Bra Size Calculator
Estimate an EU bra starting size from bust and underbust measurements in cm or inches. Explore sister sizes and read the measuring guide.
A starting point for trying on.
Neighbouring sister sizes
Similar cup volume within this chart. Shape and actual fit may differ.
How this EU Bra Size Calculator estimates a starting size
Use your underbust and bust measurements to find a size to try in the stated EU chart. A size label narrows the next comparison, but the garment still needs a fit check. This guide explains the measurement positions and the chart behind the result, including where the estimate stops.
Take two measurements with the tape level
Use a flexible tape with readable markings. For the underbust measurement, place it directly below the bust and hold it snugly around your body. Keep the tape horizontal rather than letting it rise at the back. Breathe normally while you settle the tape and read the measurement.
For the bust measurement, move the tape around the fullest part and let it rest against the body without compressing the bust. A mirror can help you check the position at the back. If you follow a particular manufacturer’s measuring instructions, use that method consistently. Repeating a reading is useful when the tape slips or the value seems unusual.
Read the band number and cup letter together
This calculator rounds the underbust measurement to the nearest 5 cm band step. Exact halfway values round up. The supported EU band labels run from 60 to 110. The cup letter is selected from the difference between the measured bust and measured underbust. These are the rules of this particular two-measurement chart.
For example, an underbust measurement of 80 cm and bust measurement of 95 cm give a 15 cm difference. That falls in the B interval below, producing EU 80B. The letter belongs with the band number: the cup volume described by a B label changes when the band changes. Comparing letters alone leaves out part of the size.
The EU cup chart used for this estimate
Cup intervals start at a 10 cm difference for AA and increase in 2 cm steps. Each interval includes its lower boundary and excludes its upper boundary. A difference of exactly 16 cm starts C, while a difference just below 16 cm stays in B. Values outside the supported range produce a coverage message instead of an invented size.
The cup-difference reference below uses AU labels in its New Zealand guide. Genory follows the Europe column in the linked international chart, where AU DD corresponds to EU E. Subsequent EU steps continue F, G and H. These references explain the chosen convention; they do not make the output a universal size across brands.
| Measured bust minus underbust | EU cup in this chart |
|---|---|
| 10 to less than 12 cm | AA |
| 12 to less than 14 cm | A |
| 14 to less than 16 cm | B |
| 16 to less than 18 cm | C |
| 18 to less than 20 cm | D |
| 20 to less than 22 cm | E |
| 22 to less than 24 cm | F |
| 24 to less than 26 cm | G |
| 26 to less than 28 cm | H |
What to do when measurements sit near a boundary
A small change in tape position can move a result across a table boundary. With an 80 cm underbust, bust readings of 95.9 cm and 96.1 cm fall on opposite sides of the B/C boundary here. Repeat the measurement with the tape at the same height, then consider both nearby sizes when checking the actual fit.
The band has boundaries too. An underbust reading of 82.5 cm rounds to band 85 under this method. The calculator flags readings near a boundary because a single label can otherwise suggest more certainty than the measurement supports. That notice does not identify a problem with your body.
Use sister sizes when the band needs adjustment
For EU 80B, the neighbouring sister sizes in this chart are 75C and 85A. Moving down one band step moves up one cup step; moving up a band step moves down one cup step. The aim is a similar cup volume within that grading system while changing the band.
Treat those labels as candidates to compare. A sister size can be useful when the cups seem suitable but the band feels too firm or too loose. If the band feels right and the cup does not, compare the neighbouring cup on the same band as well. Cup shape and the construction of a specific style can still differ between the options.
Check the garment after reading the result
Look at the band and cups separately when trying on. Note whether the band stays where you expect as you move and how the cup edges rest against the body. Adjust the straps as intended for that product before deciding whether the whole bra feels comfortable.
Describe the observation you want to change, such as a loose band or space at the top of a cup. That is more useful for the next comparison than assuming a calculated label must suit every style. Check the manufacturer’s own chart and fitting advice. A professional fitting is another option when several nearby sizes remain difficult to distinguish.
Units, supported coverage and measurement privacy
The cm/in switch converts the measurements using 2.54 cm per inch. Output remains an EU size in either input unit. It does not become a UK or US size when you select inches. For another sizing system, use the appropriate retailer’s conversion chart rather than converting the band label as though it were a length.
This tool covers EU bands 60 to 110 and cups AA to H. That is a limit of the bundled chart, not a limit on available bodies or products. Your entries stay in the calculator’s browser state. They are not saved to a preset, added to the page URL or sent as measurement requests. Reloading starts the tool from its example again.
Common questions
Why does another bra size calculator give a different answer?
Calculators can use different measurements, rounding rules or fitting approaches. Check which sizing system and chart each one uses. The method on this page is a conventional two-measurement EU estimate; another result can be a different starting point rather than an arithmetic error.
Does selecting inches give me a US bra size?
No. Inches change only the input unit. The displayed band and cup remain in the stated EU chart, including its EU cup sequence. The result panel names that system.
Are sister sizes an exact replacement?
They aim for similar cup volume within a size-grading system while changing the band. They can still differ in shape and feel. Try the relevant style and judge the fit rather than treating the labels as interchangeable products.
What does “outside this chart” mean?
Your measurements may be beyond the range covered here. First check the unit and tape reading, then use a manufacturer’s chart with broader coverage if needed. The message does not establish that your measurements are invalid.
Can I use the calculator without saving personal measurements?
Yes. No account is needed and the tool does not save the entered measurements. You can make your own note of a result if you want to compare it later, together with the sizing system and method used.