Quick bra size calculator: two measurements
Enter snug underbust and standing bust in the bra size calculator. For help with how to measure bra size, open the illustrated guide. This quick bra calculator estimates a starting label from two readings.
FREE · INCHES OR CM · NO SIGN-UP
Bra Size Calculator
Find a starting band and cup size.
Use this bra size calculator to turn underbust and bust measurements into a size to try. Enter inches or centimeters, compare international labels, and find sister sizes when you need a different band.
✓ No sign-up✓ Measurements stay on your device✓ 5 sizing systems
BRA SIZE & CUP SIZE CALCULATORHow we calculate ↗
Feedback or ideas? Email usHelp us improve this calculator.
02 / BAND & CUP SIZE
Your bra size result
Your band and cup size will appear here, with calculation notes and options for size conversion, sister sizes and checking a bra’s fit.
Starting sizeSister sizesFit advice
02 / YOUR STARTING SIZE
Quick estimateA size to try, not a promise of fit. Your comfort comes first.
YOUR NEXT STEP
Which bra size should you try first?
A suggested order, not a prediction that the first option will fit best. Check the specific brand’s size chart and return conditions before ordering.
Compare a tighter or looser bandSee adjacent sister sizes
SAME CUP VOLUME, DIFFERENT BAND
Your sister sizes.
Use an adjacent sister size when the cups fit but the band needs adjusting. The fit and support will still change.
Find this size in another countryUS, UK, EU, FR and AU labels
A LABEL FOR EVERY LOCATION
Your size around the world.
Approximate label equivalents, not a universal brand fit. EU/FR labels here follow cup-step conversion, not a separate 2 cm measurement formula. Always check the retailer’s chart.
Check a bra you have tried onGet advice from what you notice
03 / MAKE IT FEEL RIGHT
How does this size fit?
Check the bra in the selected size. Start with one issue, then add any others below. For a different label, use “I know my size”.
Size feels close, but the shape feels wrong? →TRY IT ON, THEN CHECK
Anything else you notice?
Add other problems with this same bra. We consider them together.
First, settle the bra before judging its fit
Gently settle tissue into the cups and adjust straps. Recheck before changing sizes. Do not force a movement that feels uncomfortable.
For a wired bra, check wire placement; a wireless center need not sit flat. Do not keep wearing a bra that hurts. If repeated trials do not help, use a personal fitting service.
Fitting reference: Bravissimo ↗How did we get this result?
How to use the bra size calculator
Choose a bra size calculator mode, enter your details and select “Find my starting size”. The bra calculator returns a band and cup label, such as 34D. Use your bra size calculator result to choose sizes to try, then check their actual fit.
Six-measurement bra size calculator
Enter loose, snug and tight underbust, plus standing, leaning and lying bust. The bra size calculator offers standard and weighted methods. This bra fitting calculator uses those readings to suggest one or two cup labels.
Bra size calculator for a known label
Choose “I know my size” in the bra size calculator. Select the label’s sizing system, band and cup, then “Convert & check my size”. This bra calculator converts labels without asking you to measure again.
Keep your bra size calculator result: copy, download or print it. The bra fitting calculator also includes a Try-on journal. Save a bra’s brand, style, label and fit observations on this device, then reuse a comfortable bra as a reference.
Bra size calculator in inches or cm
Select the unit on your tape. The bra size calculator in cm uses 2.54 centimeters per inch. Switching to the bra size calculator in inches converts entered values. Decimals such as 34.5 are accepted; you do not need to round first.
Bra size calculator example: 34D
34-inch underbust + 38-inch bust → 34D in US or UK sizing. The same readings are 86.36 cm and 96.52 cm. This example uses Quick estimate; the six-measurement method can produce a different result. Compare these labels in the bra size chart.
MEASURING GUIDE
How to measure bra size at home
To measure bra size at home, use a soft tape and a mirror. The bra size calculator needs full circumferences, not flat widths. This guide explains how to measure bra size with level tape. Avoid padding; take six-measurement readings without a bra.
01 / UNDERBUST
1. Underbust for the bra size calculator
Wrap the tape directly below your breasts and around your back. Breathe normally and keep it comfortably snug. Enter this reading into the bra size calculator without adding inches. Accurate tape placement matters when you measure bra size.
02 / BUST
2. Bust for the bra size calculator
Wrap the tape around the fullest part of your bust, keeping it level and gently touching. Do not compress tissue. Before entering the bra size calculator reading, check in a mirror that the tape has not slipped.
03 / THE LITTLE DETAILS
3. Enter your bra size calculator readings
Choose inches or cm for every field in the bra size calculator. A quarter inch is 0.25; half an inch is 0.5. For illustrated instructions on how to measure bra size, select “Guide me through measuring”.
Can I use the bra size calculator without a tape?
Nonstretch string and a ruler are a less precise substitute for a measuring tape. The bra size calculator does not estimate from height, weight, clothing size or photos. To measure bra size, you still need circumference readings.
How does the six-measurement bra size calculator differ?
This bra size calculator mode uses three underbust tensions and three bust positions. The bra fitting calculator illustrates each reading. If leaning or lying is uncomfortable or inaccessible, choose Quick estimate. Neither method guarantees a fit.
COMPARE MEASURING METHODS
Why does a bra size calculator give a different result?
One bra calculator may use different tape positions, rounding or cup sequences from another. Before reusing readings in this bra size calculator, compare the measuring guides below. The comparison explains how to measure bra size; it does not calculate a custom result for each brand.
BELOW THE BUST
Enter the actual snug measurement around your ribcage, directly below your breasts. Do not add inches first. Our quick method rounds to an even band; six-measurement mode also uses loose and tight measurements.
Read this measuring method ↗INTERNATIONAL SIZE CONVERSION
Bra size chart: US, UK, EU, FR and AU
Use the bra size chart to compare band and cup labels. For a full UK to US conversion, enter your existing label in the bra size calculator. You can download either bra size chart as CSV for reference.
| UK | US / CA | EU / FR | AU / NZ |
|---|---|---|---|
| D | D | D | D |
| DD | DD | E | DD |
| E | DDD | F | E |
| F | G | G | F |
The bra size chart covers US/Canada, UK, EU, France/Spain/Belgium and Australia/New Zealand. US lettering varies by brand. The bra size calculator uses EU cup-step equivalents, not a separate two-centimeter formula. Check the retailer’s bra size chart before ordering.
WHEN THE CUPS FIT BUT THE BAND DOES NOT
Sister sizes in the bra size calculator
A sister size bra calculator pairs a different band with approximately the same cup volume. In your bra size calculator result, open “Compare a tighter or looser band” for adjacent options within the supported range.
32DDTighter band↔34DStarting size↔36CLooser band
For UK 34D, the bra size calculator shows 32DD for a tighter band and 36C for a looser band. A larger letter does not mean more volume when the band changes. Use the bra size chart to check labels; support and shape may still differ.
AFTER YOU TRY IT ON
Use the bra size calculator after trying a bra
Why are my bra cups gaping?
A loose whole cup and a gap only at the top can have different causes. In the bra size calculator, select the gaping observation. The bra fitting calculator gives size and shape suggestions before you automatically choose a smaller cup.
What if the cups spill and gape?
Select both observations in the bra size calculator. The combined checklist considers a possible shape mismatch, rather than separately recommending a larger and smaller cup.
What if one breast is larger?
Check that the larger side is contained comfortably. The bra size calculator’s fit advice suggests adjusting the smaller side’s strap or considering an optional insert without compressing the larger side.
Open “I’ve tried it on — check the fit” in the bra size calculator for band, cup, strap and movement observations. This bra fitting calculator cannot diagnose discomfort or guarantee a product match. Separate sports, nursing, postsurgery and brand-specific S/M/L sizing are not provided.
FORMULAS & LIMITS
How the bra size calculator works
The bra size calculator estimates labels from circumferences using the formulas below. Read the calculation notes beside your result. The bra size chart explains common label equivalents; it does not test a particular bra’s shape or stretch.
Quick bra size calculator formula
Band and cup size calculator formula
The bra size calculator converts centimeters using 2.54 cm per inch. It rounds snug underbust to an even band, with odd-number ties rounding up, then subtracts that band from standing bust. One inch represents one cup step; differences below one inch map to AA.
The bra size calculator does not add four inches. Fractional cup steps produce two neighboring candidates. Supported base bands run from UK/US 26 to 60, with cups AA through UK MM. Unsupported measurements return an explanation.
Six-measurement bra size calculator methods
Standard and weighted bust estimates
The bra size calculator follows an independent implementation of the community manual sizing guide. Standard mode uses leaning bust, or averages standing, leaning, and lying measurements when leaning exceeds standing by more than 2.5 inches. Weighted mode uses (2 × standing + leaning + 2 × lying) ÷ 5.
Adjusting the cup estimate
The bra size calculator subtracts loose underbust, then adjusts cup steps by half the rounded difference between loose underbust and band: upward when loose is larger, downward when smaller. Tight underbust informs comfort notes. This is not a clinically validated fitting method.
Bra size calculator label conversion
UK, US, EU, FR, and AU equivalents
Choose “I know my size” in the bra size calculator to convert an existing label without entering measurements. This bra size converter matches band labels and cup steps. For example, UK 34E corresponds approximately to US 34DDD, EU 75F, FR 90F, and AU 12E.
The bra size calculator uses the US sequence DD, DDD, G, H. Brand half cups, Japanese sizing, and Italian sizing are not calculated. Conversion changes a label, not your body measurements or the construction of a bra.
Bra size calculator privacy and saved records
What stays on your device?
The bra size calculator runs locally without an account or photo upload. Body measurements are not transmitted or stored by this site. Refreshing clears the form. The optional journal saves labels, brands, styles, observations, and notes only with your consent.
Copy, download, or print your bra size fit card when you want a record of your measurements and advice. Journal records can be updated, reused, deleted, or exported as JSON. They stay in this browser; there is no cloud synchronization.
BRAND SIZE GUIDES
Compare your result with the brand’s bra size chart
After using the bra size calculator, check the brand’s own bra size chart and measuring instructions. These links do not provide stock checks, price comparisons or individual product matching.
COMMON SIZING QUESTIONS
Bra size calculator FAQ
Is this the A Bra That Fits calculator?
No. The A Bra That Fits calculator is a separate community tool; this bra size calculator is not affiliated with that project. Our six-measurement method independently implements its community manual sizing guide. An A Bra That Fits calculator result may differ from ours.
How does the bra size chart compare DD and E?
In this bra size chart, UK DD matches US DD and EU E; UK E matches US DDD and EU F. Select the right system in the bra size calculator. Cup letters need a band size and sizing system to be meaningful.
Why does the bra size calculator show two cup sizes?
The bra size calculator estimate falls between cup steps. Both labels are candidates to try, not a proprietary half-cup size. In the bra fitting calculator’s fit checker, select the cup of the bra you actually tried.
Can the bra size calculator work without measurements?
With an existing label, choose “I know my size” in the bra size calculator to compare equivalents and fit issues. Without readings or a known label, the bra calculator cannot find your size. The illustrated guide explains how to measure bra size.
How accurate is an online bra size calculator?
A bra size calculator estimates a starting label; it cannot measure shape, wire width or fabric stretch. Compare the brand’s bra size chart, try the bra, then use the bra fitting calculator to review support, cup containment and comfort while moving.
When should I measure bra size again?
Measure bra size again when your usual bras fit differently or your body changes. Check for a stretched band before changing sizes. Follow the how to measure bra size guide, then enter fresh readings in the bra size calculator.
Bra size calculator for small or large cups
The bra size calculator supports UK/US bands 26–60 and cups AA–UK MM, with corresponding labels in the bra size chart. This range does not mean every measurement combination is accepted or every retailer makes each size.
Is the bra size calculator free?
All current bra size calculator features are free, with no account required. Readings remain in the page and clear on reload. The bra fitting calculator’s optional journal saves only the try-on details you choose; there is no cloud synchronization.