Bra Size Calculator
Find your estimated bra size by providing your underbust and bust measurements.
Measurements (Inches)
Calculator guide
Bra Size Calculator
Estimate a starting band and cup size from the measurements entered on the page. Sizing systems differ by brand and country, so the result is a fitting suggestion rather than a universal or guaranteed size.
How to use the calculator
- 1Measure around the rib cage and fullest part of the bust as the page instructs, keeping the tape level.
- 2Select the units and sizing region if the tool offers those options, then submit the measurements.
- 3Try the suggested size as a starting point and check comfort, support, and the brand's own fit guide.
Important details to understand
1.Start with the right inputs
Check every number, date, unit, and selected mode before calculating. A correct formula can still give a misleading answer when an input is missing, entered in the wrong unit, or based on a different time period.
2.Know what the calculation includes
The method below describes what this tool uses. Real situations can involve extra rules, costs, calendar conventions, or personal details that are not part of the form, so compare the assumptions with your actual question.
3.Read the unit and rounding
Look at the label as well as the displayed number. Rounding can change the last digits, and results in different units or time periods are not directly comparable until you convert them consistently.
4.Treat the result as a useful check
Use the output to understand a calculation, explore a scenario, or make an initial estimate. When a result affects a formal deadline, a health decision, a contract, or a large payment, confirm it with the relevant source or qualified professional.
How the calculation works
The page compares the entered underbust and bust measurements, then maps their difference and band measurement to a size using its built-in sizing rules. Rounding, band conventions, and cup progressions vary across sizing systems.
A worked example
Two brands may label a similar fit differently because their patterns and size charts are not identical.
When this calculator is useful
Get a first size to try when shopping or compare a measurement with a retailer's sizing chart.
Planning ahead
Try a few realistic input values to see how a change in an amount, measurement, date, or rate affects the answer.
Learning the method
Follow the explanation and example to understand which inputs matter and how they are combined.
Checking your own work
Compare the result with a hand calculation, a worksheet, or a trusted source when you need an independent sense check.
Explaining a result
Keep the original inputs and units with the output so another person can understand what was calculated.
Tips for a more reliable answer
- Enter the values from the same source and keep units consistent throughout the calculation.
- Check that you selected the mode or option that matches the question you are trying to answer.
- Use the worked example to confirm you understand the inputs and the kind of result the tool returns.
- Save the inputs with the result so you can review or repeat the calculation later.
Limitations and assumptions
This estimate cannot account for breast shape, style, fabric, personal comfort, or brand variation. A numerical result does not imply a required body shape. Use fitting advice if you have pain or persistent discomfort.
Every result depends on the information entered and the method described above. The calculator cannot confirm that the inputs are complete or that its assumptions match a particular provider, policy, location, body, or real-world situation.
Frequently asked questions
Is the suggested size the same for every brand?
No. Brands and regions use different charts and garment cuts.
How tight should the measuring tape be?
Follow the on-page guidance and keep it level without compressing the body.
Does the calculator guarantee fit?
No. Treat the result as a starting point and try the garment if possible.
Why might my result differ from another calculator?
Tools can use different assumptions, units, date conventions, included costs, or rounding rules. Compare the inputs and method descriptions before deciding that one result is wrong.
What should I check if the answer looks wrong?
Review the selected mode, each entered value, the units, and any optional fields. Then compare a simple example with the method described in this guide.
Can I rely on the result for an official or high-impact decision?
Use the result as an estimate or explanation and check the limitations listed for this tool. Confirm important decisions with the relevant official source or a qualified professional.