Find a practical starting bra size from your underbust and bust measurements. Calculate your US band and cup size, check sister sizes, understand cup-volume changes and learn how to confirm the fit before buying.
US Bra Size Calculator
Enter two measurements to calculate a US bra size.
Measure your underbust snugly around the ribcage and your bust around the fullest part. The calculator uses the band measurement and the difference between band and bust to estimate your US cup size.
Measure Your Underbust
Wrap a soft tape around your ribcage directly under your breasts. Keep the tape level and comfortably snug.
Measure Your Bust
Wrap the tape around the fullest part of your bust. Keep it level and snug without compressing breast tissue.
Closest Sister Sizes
Sister sizes keep approximately the same cup volume while changing the band size in the opposite direction.
Fit Check
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How to Measure Your Bra Size Correctly
Getting a useful bra-size estimate starts with accurate measurements. Use a soft measuring tape and, preferably, a non-padded or lightly padded bra. Keep the tape level around your body and avoid pulling it so tightly that it compresses your body.
1. Measure the Underbust
Place the tape directly beneath the breasts around the ribcage. Keep the tape level and comfortably snug.
2. Measure the Bust
Measure around the fullest part of the bust without flattening the breast tissue.
3. Check the Fit
Use the calculated size as a starting point, then confirm the band, cups, center gore and straps when trying on a bra.
What Should You Wear While Measuring?
A non-padded or lightly padded bra is a good choice because thick padding can change the bust measurement. Measure while standing naturally and breathe normally. Wacoal and Victoria's Secret both recommend avoiding measurement methods that compress the bust or use overly tight tape.
How the Bra Size Calculation Works
A bra size combines a band number with a cup letter. The band represents the ribcage measurement, while the cup letter represents the difference between the bust measurement and the band size used by the sizing system.
US Band Size
US Cup Difference
The calculator then maps the difference to a conventional US cup sequence. Different brands use different size charts, so the result should be treated as a starting size rather than a universal measurement.
| Bust-to-Band Difference | US Starting Cup |
|---|---|
| Less than 1 inch | AA |
| 1 inch | A |
| 2 inches | B |
| 3 inches | C |
| 4 inches | D |
| 5 inches | DD or E |
| 6 inches | DDD or F |
| 7 inches | G |
| 8 inches | H |
| 9 inches | I |
| 10 inches | J |
| 11 inches | K |
| 12 inches | L |
US Bra Size Chart
Use this chart as a quick reference after calculating your starting size. Brand-specific charts should take priority when you are shopping for a particular bra.
| Band | A | B | C | D | DD or E | DDD or F | G | H |
|---|---|---|---|---|---|---|---|---|
| 30 | 30A | 30B | 30C | 30D | 30DD | 30DDD | 30G | 30H |
| 32 | 32A | 32B | 32C | 32D | 32DD | 32DDD | 32G | 32H |
| 34 | 34A | 34B | 34C | 34D | 34DD | 34DDD | 34G | 34H |
| 36 | 36A | 36B | 36C | 36D | 36DD | 36DDD | 36G | 36H |
| 38 | 38A | 38B | 38C | 38D | 38DD | 38DDD | 38G | 38H |
| 40 | 40A | 40B | 40C | 40D | 40DD | 40DDD | 40G | 40H |
| 42 | 42A | 42B | 42C | 42D | 42DD | 42DDD | 42G | 42H |
| 44 | 44A | 44B | 44C | 44D | 44DD | 44DDD | 44G | 44H |
What Are Sister Sizes?
Sister sizes are sizes with approximately the same cup volume but different band sizes. When the band changes, the cup letter changes in the opposite direction.
| Your Size | Sister Size Down | Sister Size Up |
|---|---|---|
| 32C | 30D | 34B |
| 34C | 32D | 36B |
| 36C | 34D | 38B |
| 38D | 36DD | 40C |
| 40D | 38DD | 42C |
| 42D | 40DD | 44C |
Victoria's Secret Bra Size Calculator: What to Know
Searches for a "Victoria's Secret bra size calculator" often mean the shopper wants a starting size for Victoria's Secret bras. This calculator is independent and is not a Victoria's Secret sizing tool.
Victoria's Secret recommends measuring around the band area and around the fullest part of the bust, then trying the calculated size on. The company also explains that cup capacity is relative to the band size. 2
| Search Intent | What This Calculator Provides |
|---|---|
| Victoria's Secret bra size calculator | A general US starting size that can be compared with the brand's current size and fit information. |
| US bra size calculator | US band and cup estimate from underbust and bust measurements. |
| Bra cup size calculator | Cup estimate based on the difference between bust and band size. |
| Band size calculator | Starting US band size from the underbust measurement. |
| Sister size calculator | Closest smaller-band and larger-band sister sizes. |
How to Know if Your Bra Fits
Measurements give you a starting size. The actual fit tells you whether the size and bra shape work together.
| Fit Check | What You Want | Possible Problem |
|---|---|---|
| Band | Snug, level and supportive | Riding up can indicate a loose band. |
| Cups | Breast tissue contained without spilling | Spillage or cutting can indicate cups are too small. |
| Center Gore | Comfortable and appropriate for the bra design | Pressure or poor contact can indicate a shape mismatch. |
| Straps | Secure without carrying all the support | Constant slipping or digging can indicate adjustment or fit issues. |
| Underwire | Encircles breast tissue without digging | Pinching can indicate an unsuitable wire size or shape. |
| Overall Comfort | Supportive without painful pressure | A different size or bra style may work better. |
Tips for Getting a More Accurate Bra Size
Why Your Calculated Size May Not Fit
Two bras with the same labeled size can feel different because bra design affects fit. Cup depth, cup width, wire shape, center-gore height, stretch, strap placement and coverage all influence how a bra feels.
This is why a measurement-based calculator should be used to establish a starting point. A physical try-on remains useful when available.
Frequently Asked Questions
Related ComfortSkillz Calculators
References
Victoria's Secret and PINK, Free Bra Fitting and How to Measure Your Bra Size.
Wacoal, Bra Fit Calculator and Home Measurement Instructions.
ThirdLove, Bra Size Calculator and Bra Size Chart.
ThirdLove, Bra Sister Sizes and Equivalent Bra Size Guide.
