Bra Size Calculator
Finding the right bra size makes a real difference in comfort and support. Our calculator helps you determine your accurate bra size using two simple measurements you can take at home.
Bra Size Calculator
How to Measure
- Band Size: Measure around your ribcage directly under your bust. Keep the tape snug but comfortable.
- Bust Size: Measure around the fullest part of your bust, keeping the tape parallel to the ground.
- Use a soft measuring tape and measure while wearing a non-padded bra for best results.
Bra Size Calculator – Find Your Perfect Fit
Finding the right bra size makes a real difference in comfort and support. Our calculator helps you determine your accurate bra size using two simple measurements you can take at home.
Why Bra Size Matters
Most women wear the wrong bra size without realizing it. An ill-fitting bra can cause shoulder pain, back discomfort, poor posture, and visible lines under clothing. When your bra fits correctly, you’ll notice better support, improved comfort throughout the day, and a more flattering silhouette under your clothes.
How to Measure for a Bra
You’ll need a soft measuring tape and a mirror. Wear a non-padded bra or go braless for the most accurate results.
Band Measurement (Underbust): Stand straight and wrap the measuring tape around your ribcage, directly under your bust. The tape should sit snug against your skin without digging in. Keep it parallel to the floor and take note of this measurement. This determines your band size.
Bust Measurement (Overbust): Keep standing straight and measure around the fullest part of your bust. Don’t pull the tape too tight—it should rest comfortably against your body. Again, keep the tape level all the way around. This measurement helps calculate your cup size.
Take each measurement 2-3 times to ensure accuracy. If you get slightly different numbers, use the average.
Cup Sizes
Cup size is determined by the difference between your bust and band measurements:
| Difference (inches) | Cup Size |
|---|---|
| Less than 1″ | AA |
| 1″ | A |
| 2″ | B |
| 3″ | C |
| 4″ | D |
| 5″ | DD/E |
| 6″ | DDD/F |
| 7″ | G |
| 8″ | H |
| 9″ | I |
| 10″ | J |
Understanding Your Results
Band Size
The band provides 80% of your bra’s support. It should fit firmly on the loosest hook when new, allowing you to tighten it as the elastic stretches over time. You should be able to fit two fingers under the band comfortably.
Cup Size
Cup size isn’t absolute—it’s relative to your band size. A 34D has the same cup volume as a 36C or 32DD. These are called “sister sizes.”
Sister Sizes Chart
If your calculated size doesn’t feel right, sister sizes offer alternatives with the same cup volume:
| Your Size | Sister Size (Smaller Band) | Sister Size (Larger Band) |
|---|---|---|
| 32C | 30D | 34B |
| 34C | 32D | 36B |
| 36C | 34D | 38B |
| 34D | 32DD | 36C |
| 36D | 34DD | 38C |
| 38D | 36DD | 40C |
| 34DD | 32DDD/E | 36D |
| 36DD | 34DDD/E | 38D |
| 38DD | 36DDD/E | 40D |
How to use sister sizes: If your band feels too loose, go down a band size and up a cup size. If the band feels too tight, go up a band size and down a cup size.
International Size Conversion Chart
Bra sizing varies by country. Use this chart when shopping internationally:
| US Size | UK Size | EU Size | FR Size | AU Size | JP Size |
|---|---|---|---|---|---|
| 30A | 30A | 65A | 80A | 8A | 65A |
| 32A | 32A | 70A | 85A | 10A | 70A |
| 34A | 34A | 75A | 90A | 12A | 75A |
| 36A | 36A | 80A | 95A | 14A | 80A |
| 32B | 32B | 70B | 85B | 10B | 70B |
| 34B | 34B | 75B | 90B | 12B | 75B |
| 36B | 36B | 80B | 95B | 14B | 80B |
| 32C | 32C | 70C | 85C | 10C | 70C |
| 34C | 34C | 75C | 90C | 12C | 75C |
| 36C | 36C | 80C | 95C | 14C | 80C |
| 32D | 32D | 70D | 85D | 10D | 70D |
| 34D | 34D | 75D | 90D | 12D | 75D |
| 36D | 36D | 80D | 95D | 14D | 80D |
| 32DD | 32DD | 70E | 85E | 10DD | 70E |
| 34DD | 34DD | 75E | 90E | 12DD | 75E |
| 36DD | 36DD | 80E | 95E | 14DD | 80E |
| 34DDD | 34E | 75F | 90F | 12E | 75F |
| 36DDD | 36E | 80F | 95F | 14E | 80F |
Key differences:
- US/AU sizing is the same
- UK sizing differs mainly in larger cup sizes (DD, E, F progression)
- EU/FR adds 10 to band numbers (34 becomes 75)
- Japanese uses centimeter-based bands
When to Remeasure
Your bra size changes over time. Remeasure every 6-12 months, or whenever you experience:
- Weight changes of 10+ pounds
- Pregnancy or breastfeeding
- Hormonal changes
- Changes in fitness routine
- Bras feeling uncomfortable when they used to fit well
Signs Your Bra Doesn’t Fit
Use this checklist to identify fit problems:
| Problem | Too Small | Too Large | Wrong Style |
|---|---|---|---|
| Band | Red marks, can’t breathe comfortably, painful | Rides up back, rotates around body | – |
| Cups | Spillage over top/sides, underwire on breast tissue | Gaps and wrinkling, cups collapse | Doesn’t suit breast shape |
| Straps | Digging into shoulders painfully | Constantly sliding down | Too wide or narrow set |
| Gore (center piece) | Doesn’t lay flat against chest | Floats away from body | Wrong wire width |
Bra Fit Guide
| Area to Check | Proper Fit | What It Means If Not Right |
|---|---|---|
| Band | Sits level around body, parallel to floor | If it rides up: band too loose |
| Band tightness | Snug on loosest hook, 2 fingers fit underneath | If too tight on loosest hook: band too small |
| Cup coverage | All breast tissue contained, no spillage | Spillage: cup too small; Gaps: cup too large |
| Underwire | Sits flat against ribcage under breasts | On breast tissue: wrong size or shape |
| Gore (center) | Lays flat against sternum | Floating: cups too small or wrong style |
| Straps | Stay in place, don’t dig in | Falling: band too loose; Digging: band doing no work |
Tips for the Best Fit
Try Before You Buy: Sizes vary between brands and styles. What works in one brand might not work in another.
Start on the Loosest Hook: This lets you tighten the band as it stretches, extending the life of your bra.
Scoop and Swoop: After putting on your bra, lean forward and scoop all breast tissue into the cups from the sides and bottom. This ensures everything sits where it should.
Check the Band: It should sit level all the way around your body, parallel to the floor. If it rides up, you need a smaller band.
Test the Straps: You should be able to slide two fingers underneath comfortably. They should stay put without digging in.
Move Around: Reach up, bend over, twist side to side. Your bra should stay in place through normal movement.
Bra Style Fitting Differences
Different styles fit differently, even in the same size:
| Bra Style | Typical Fit Notes | When to Adjust Size |
|---|---|---|
| T-shirt Bra | True to size, full coverage | May need to size down cup if heavily padded |
| Push-up | Runs small in cup due to padding | Often need to go up one cup size |
| Balconette | Less coverage on top | Good for full-on-bottom shapes |
| Plunge | Deep center gore | May gap at top if full-on-top |
| Sports Bra | Compression fit, runs small | Size up for comfort, especially high-impact |
| Bralette | Stretchy, forgiving fit | Often sized S/M/L; size up if between |
| Wireless | More flexible fit | May need smaller band for support |
| Strapless | Should fit tighter than regular | Go down one band size |
Common Fitting Problems and Solutions
| Problem | Possible Causes | Solutions to Try |
|---|---|---|
| Gap at top of cups | Cup too large, wrong style for shape | Try smaller cup or different cut (balconette vs full cup) |
| Spillage at sides | Cup too small, wires too narrow | Go up a cup size, try wider wire style |
| Band rides up back | Band too large | Go down a band size, up a cup (sister size) |
| Straps dig into shoulders | Band too loose, straps carrying weight | Tighten band or size down, adjust straps |
| Underwire pokes sides | Wrong wire width | Try different brand with wider/narrower wires |
| Center gore doesn’t touch chest | Cups too small or wires too narrow | Go up cup size or try wider wire |
| Everything feels wrong | Outside common size range | Seek specialty retailers for extended sizes |
Bra Lifespan and Replacement Guide
| Sign | What It Means | Action Needed |
|---|---|---|
| Band stretches out on tightest hooks | Elastic worn out | Replace bra |
| Cups lost shape, flatten out | Fabric breakdown | Replace bra |
| Underwires poking through fabric | Wear and tear | Replace immediately |
| Straps won’t tighten enough | Elastic stretched | Replace bra |
| Visible wear after 6-12 months regular use | Normal lifespan reached | Replace bra |
Extend bra life: Hand wash in cool water, air dry flat, alternate bras (don’t wear same one daily), store properly (don’t fold cups).
Frequently Asked Questions
How often should I replace my bras?
Replace bras every 6-12 months with regular wear. Signs you need new bras include stretched-out bands, flattened cups, broken underwires, or straps that won’t adjust tight enough. Hand washing and air drying extends bra life significantly.
Why do I measure as a different size than what I currently wear?
Many women wear the wrong size without knowing it. Stores often “fit” customers into whatever sizes they stock. Your actual measurements might fall outside common retail sizes, leading to approximations that don’t fit properly.
Can I measure myself or do I need help?
You can measure yourself using a mirror to check that the tape sits level. However, having someone else measure you often yields more accurate results, especially for the band measurement.
What if my measurements fall between sizes?
Round to the nearest even number for band size. If you’re between cup sizes, try both and see which feels more comfortable. Body shape affects fit as much as measurements do.
Do different brands fit the same?
No. Sizing varies considerably between brands and even between styles within the same brand. What fits in one brand might run large or small in another. Always try before buying when possible.
Why does the calculator add 4-5 inches to my band measurement
This is the traditional fitting method used in the US. Some modern fitting guides skip this step and use your actual underbust measurement as the band size. Try both methods to see which works better for your body.
What’s the difference between DD, DDD, and E cups?
US sizing uses DD and DDD, while UK sizing uses DD and E. Some brands use different progressions (DD, DDD/E, F, G) while others go DD, E, F, G. Always check the specific brand’s size chart.
My calculator result seems too large/small. Is it wrong?
The calculator provides a starting point based on standard measurements. Your actual size depends on breast shape, body proportions, and personal preference. Use the result as a guide, then adjust based on how bras actually fit you.
Can I use this calculator during pregnancy or while breastfeeding?
Yes, but know that your size will change frequently during these times. Measure every few weeks as your body changes. Many women go up 1-2 band sizes and multiple cup sizes during pregnancy and nursing.
What if I can’t find my size in stores?
Many retailers only stock a limited size range (typically 32-38 bands, A-DD cups). Specialty lingerie stores and online retailers carry extended sizes. Brands like Panache, Freya, Elomi, and Curvy Kate offer sizes beyond typical retail ranges.
How tight should a new bra feel?
A new bra should feel snug but not uncomfortable on the loosest hook. If it feels perfect on the tightest hooks, it’s already too loose and will become unwearable as it stretches. Some tightness initially is normal and expected.
Why do my breasts look different sizes when measuring?
Most women have slight asymmetry. Fit to your larger side and use padding or inserts on the smaller side if needed. A difference of up to one cup size is completely normal.
Does weight loss or gain affect bra size?
Yes. Even small weight changes can affect bra size. Breast tissue contains fat, so weight fluctuations often change cup size. Band size may also change with overall body weight shifts.
Can exercise or muscle building change my bra size?
Building chest muscles (pecs) can add bulk to your ribcage, potentially increasing band size. Intensive training might also reduce breast tissue, affecting cup size. Athletes often need to remeasure more frequently.
What’s the largest/smallest bra size available?
Specialty brands make sizes far beyond typical retail offerings. Bands range from 26-56+ and cups from AA to N+ in some brands. If you measure outside common sizes, specialty retailers can help.