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 – 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.

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