Your result
Click Calculate
Enter your values, then click Calculate result.How this calculator helps
This bra size calculator converts two measurements into a disclosed chart starting point. It rounds the underbust upward to an even-inch band, rounds the bust upward to a whole inch and uses the difference to select corresponding US and UK cup labels. The page shows both rounded measurements and the cup difference, so you can see how the answer was formed. Sister-size options illustrate moving one band step while changing the cup step in the opposite direction. This is a sizing worksheet to compare with the product’s own chart and a fitting, not a universal anatomy formula. It does not implement the six-measurement A Bra That Fits calculator.
How to use it
- 1
Take a level snug underbust and fullest-bust measurement.
- 2
Choose inches or centimetres and enter both measurements in that unit.
- 3
Click Calculate result and inspect the rounded band and bust values.
- 4
Compare US and UK labels with the exact product’s size chart.
- 5
Try the bra and assess comfort, band position and cup containment rather than relying only on the label.
Formula and methodology
Convert centimetres to inches by dividing by 2.54 if needed. Band B = 2 × ceil(underbust inches/2). Rounded bust C = ceil(bust inches). Difference D = C − B indexes the disclosed US/UK chart for 0–15 inches. Sister options move the band by two inches and the cup index by one opposite step.
The calculator applies the displayed arithmetic to the values entered on this device. It does not silently load a local tax rate, currency conversion or commercial assumption.
Worked calculation example
For an underbust of 33 inches and a bust of 39 inches, the band rounds to 34 and the bust stays 39. The difference is 5 inches. This chart labels that starting point 34DD/E in US notation and 34DD in UK notation. The smaller-band sister option is 32DDD/F US or 32E UK, while the larger-band option is 36D in both systems. Those labels describe alternatives to try, not a guarantee of the same fit in every design. Entering the equivalent 83.82 cm and 99.06 cm uses the same conversions and produces the same starting chart labels.
How to interpret your result
The result is a starting label under one clearly described chart convention. It does not describe your body’s volume or establish which style will be comfortable. If the chart result conflicts with the product’s own guide, treat that as a convention or fitting question rather than forcing the tape measurements to produce a preferred label.
For different inputs or formulas, use Supplied Clothing Chart Matcher; Adult Shoe Chart Converter; Length Conversion Calculator.
Related questions this calculator covers
- Bra measurement calculator in inches or centimetres
- Disclosed band rounding and US/UK cup labels
- Neighboring sister-size chart options
Scenario comparison
| Scenario | What it shows |
|---|---|
| 33-inch underbust, 39-inch bust | Rounded band 34 and difference 5 give 34DD/E US / 34DD UK. |
| Exact unit conversion | 83.82 cm and 99.06 cm produce the same rounded values and labels. |
| Outside chart | A negative rounded difference or unsupported band is rejected instead of inventing a label. |
Common mistakes to avoid
- Comparing cup letters without checking whether the brand uses US or UK labels.
- Mixing an inch underbust with a centimetre bust.
- Treating sister-size notation or a two-measurement estimate as a fit guarantee.
Convert centimetres by 2.54, apply the stated rounding and subtract the displayed values. Check the corresponding cup labels against the linked chart and the product guide. Recheck tape level and assess the actual garment after trying it on.
Authoritative reference and additional source reference. Bare Necessities publishes measurement guidance and cup notation; Bravissimo provides garment fit checks. The page’s explicit decimal-boundary rounding is disclosed SolvePilot arithmetic, not every brand’s sizing method.Use a size label as a trial, not a verdict
Record the two measurements, the selected unit and the chart convention before ordering. If a garment feels wrong, change one factor at a time during a fitting: first the band or cup position being tested, then the style or construction. Changing several labels and styles together makes it harder to learn what caused the difference. The calculator can organize the starting comparison but cannot inspect a garment on your body.
The same printed cup letter does not represent a fixed physical volume across band sizes. That is why a change in band can require a change in cup notation. Keep the combined band-and-cup label intact when comparing products. Avoid interpreting a cup result as a measurement of health, attractiveness or anatomy; it is a garment labeling convention for a fitting task.
Check sensitive measurement boundaries carefully
An underbust just above an even inch rounds to the next even band in this model. A bust just above a whole inch rounds upward as well. Those two operations can cause an abrupt label change even when the raw measurements changed only slightly. The calculation displays the rounded inputs rather than hiding the boundary. Repeat the measurements if the difference seems surprising.
When the rounded band exceeds the rounded bust, the page refuses to invent a negative cup step. That can happen around a boundary even with a bust slightly larger than the raw underbust. It is a limitation of this simple chart, not a conclusion about the person. Use the brand’s fitting guidance or a fitting service rather than stretching the chart beyond its supported range.
What can affect the result?
Chart convention
A chart result depends on the convention used. This page does not add four or five inches to the underbust and does not reproduce every retailer’s fitting method. Check the brand’s instructions before comparing labels.
Rounding boundaries
A small measurement change can cross an even-band or whole-inch bust boundary. The displayed rounded values make that change visible. Recheck tape placement and rounding before treating a one-cup change as a meaningful fit conclusion.
Cup notation
The same cup index can have different labels after D in US and UK notation. A letter printed on a label must be read with its sizing system. The chart comparison does not establish a universal European band conversion.
Style and sister options
A sister label changes band and cup steps together. Material stretch, wire geometry and construction can still change the fit. An option outside the bounded chart is marked unavailable instead of being extrapolated.
Privacy and browser processing
Values entered on this page are processed in the current browser session. SolvePilot does not require an account and does not receive the values entered into the calculator. Refreshing or closing the page clears the working values unless the browser itself restores a previous session. Avoid entering identifying or account information because the calculation needs summary values only.
Accuracy and verification
Accuracy depends first on input quality. Confirm definitions, scales, dates and source information before entering a value. Keep an independent record of any result used for planning because this page does not create an official statement or retain a calculation history.
Limits of this estimate
A two-measurement, explicitly rounded chart estimate for bands 28–58 and cup differences 0–15 inches. Not clinical measurement, breast volume, a complete international conversion table, a six-measurement algorithm or guaranteed fit. Confirm the particular brand and style; a professional fitting can resolve uncomfortable or inconsistent results.
Sources and review information
Frequently asked questions
How do I calculate a bra size with this chart?＋
Convert both measurements to inches, round underbust upward to an even band and bust upward to a whole inch, then read the difference in the disclosed cup chart.
Why are US and UK cup labels different?＋
Their naming sequences diverge after some early cup steps. The page reports both labels from the same disclosed difference index; check the sizing system on the product.
Can I measure in centimetres?＋
Yes. Both measurements are converted with exactly 2.54 centimetres per inch before the same rounding steps are applied.
Is this the A Bra That Fits calculator?＋
No. SolvePilot’s independent two-measurement chart is different from that named calculator’s six-measurement method. We do not imply affiliation or equivalent fit predictions.
What are sister sizes?＋
They are neighboring band-and-cup labels obtained by moving the band one step and the cup in the opposite direction. They are options to compare during fitting, not interchangeable guarantees.