Bra Sizes & Cup Size Chart (AA–HH) + Band & Bust Measuring Guide
Bra sizing should feel simple: measure your band and bust, match the chart, then shop the bra type that fits your body and your goal. This guide breaks down bra sizes, boob sizes, breast cup size comparisons, sister sizing, and the most common fit mistakes—so you can get a better fit on the first try.
Bra Sizes, Boob Sizes, and Breast Cup Size Comparison (What It Actually Means)
Your bra size is not “small/medium/large.” It’s a two-part measurement: band (numbers) + cup (letters). When both are correct, bras feel supportive, flattering, and comfortable—without digging, gaping, or sliding.
Every body is different, which means every bust is different—size, shape, density, projection, and spacing can change how a bra fits. Breasts also change across life stages (hormones, exercise, weight shifts, pregnancy, postpartum, and more). That’s why measuring periodically matters: your “old size” can quietly become the wrong size without you noticing.
The most common reason bra shopping feels frustrating is not “your body”—it’s incorrect sizing. Many people are in the wrong bra size because they learned outdated methods or buy based on “what they always wear” instead of current measurements. When the band and cup are right, you’ll notice:
- Better support: less shoulder strain and less bouncing.
- Better shape: tops fit smoother and lines look cleaner.
- More comfort: fewer wire marks, less spillage, less gaping.
- More confidence: your bra feels like it belongs on your body.
How to Measure Bra Sizes (Accurate in 3–5 Minutes)
Use a soft tape. Measure in inches. Keep the tape level and snug (not tight). For best accuracy, measure over a non-padded bra or bare skin.
Step 1 — Measure your underbust (band)
- Stand straight with relaxed shoulders.
- Place the tape directly under your bust, around your ribcage.
- Keep the tape parallel to the floor and snug (not painful).
- Write down the measurement (inches).
Step 2 — Measure your bust (fullest point)
- Wrap the tape around the fullest part of your bust (often at nipple level).
- Keep the tape level and comfortably snug.
- Write down the measurement (inches).
How to calculate your bra size
Start with band. Then estimate cup using the difference between your bust and underbust. This gets you very close—final fit can vary slightly by brand and by style (plunge, full coverage, unlined, etc.).
Band size (quick guide)
- If your underbust is an even number, that’s a strong starting band.
- If it’s an odd number, round to the nearest even number.
- If you prefer a snug feel, choose the lower even number; for a softer feel, choose the higher.
Cup size (difference method)
Cup is based on the difference between bust and underbust. Example: Underbust 34" and Bust 37" → difference 3" → roughly C cup. Use fit checks later to confirm.
| Difference | Cup size |
|---|---|
| 0–½" | AA |
| ½–1" | A |
| 1–2" | B |
| 2–3" | C |
| 3–4" | D |
| 4–5" | DD / E |
| 5–6" | DDD / F |
| 6–7" | G |
| 7–8" | H |
| 8–9" | HH |
Bra Cup Sizes From AA to HH (What Each Cup Represents)
Cup letters represent volume based on the difference between bust and underbust. AA–D are often similar across systems, while DD+ can vary by brand labeling. Use measurements + fit checks for best accuracy.
Bra cup sizing exists to match your breast volume with a cup shape that supports without cutting in or gaping. The goal is simple: the cup should fully contain your breast tissue (including sides) while the band stays stable around your ribcage.
If you’re constantly adjusting straps, pulling cups up, or feeling spillage, your size or your style likely needs a change. For example, if you gap in a full-coverage cup, a plunge or unlined style often fits better (same size, different shape).
US / UK / EU cup conversion (DD+ reference)
Note: brand standards vary. Use this as a reference, not a replacement for fit checks.
| USA | UK | EU |
|---|---|---|
| DD/E | DD | E |
| DDD/F | E | F |
| G | F | G |
| H | FF | H |
| I | G | I |
| J | GG | J |
| K | H | — |
| L | HH | — |
| M | J | — |
| N | JJ | — |
| O | K | — |
If a product page includes brand-specific sizing notes, follow that first.
Sister Sizes (The Fastest Way to Fix a “Close But Not Perfect” Fit)
Sister sizes keep cup volume similar while changing band size. This is the #1 trick for dialing in comfort quickly.
The rule
If you go up a band size, go down a cup. If you go down a band size, go up a cup.
| If you wear | Band too tight? | Band too loose? |
|---|---|---|
| 34D | Try 36C | Try 32DD |
| 36C | Try 38B | Try 34D |
| 34DD | Try 36D | Try 32DDD |
| 38DD | Try 40D | Try 36DDD |
When to use sister sizing
- Band rides up: go down a band (and up a cup).
- Band feels painful: go up a band (and down a cup) or try a different style.
- Cups fit, band doesn’t: sister size immediately.
- Different styles fit differently: plunge vs full coverage can change how the same size feels.
How to Know If Your Bra Fits (Fast Fit Checklist)
Use these signals to confirm your size and avoid the most common “almost right” mistakes.
Green flags (good fit)
- Band: level around your body, doesn’t ride up, snug on the loosest hook.
- Cups: smooth edges, no cutting in, no gaping, no wrinkling.
- Gore (center): lies flat (or close to flat) against your sternum for wired bras.
- Straps: supportive but not digging; you can fit two fingers underneath.
- Movement: you can lift arms and bend without cups shifting or spilling.
Red flags (quick fixes)
- Quad-boob/spillage: cup too small → go up a cup (or try fuller coverage).
- Gaping: cup too big or style mismatch → go down a cup or try plunge/unlined.
- Band rides up: band too big → go down a band (and up a cup).
- Straps dig: band too big or cup too small → fix band/cup first.
- Underwire pokes: wrong shape/size → adjust size or switch style.
Choose the bra style that matches your goal
Even with the right size, the wrong style can feel “off.” Use these shortcuts:
- Lift/cleavage: Push-Up
- Low neckline: Plunge
- Smooth under tops: T-Shirt
- Maximum support/coverage: Full-Figure / Full-Coverage
- Light feel / natural shape: Unlined
- No wire feel: Wireless
- High impact movement control: Sports
- Smoother profile: Minimizer
Cup-by-Cup Guide (AA, A, B, C, D, DD/E, DDD/F, G, H, HH)
Use this guide to understand what each cup typically needs: support level, best bra styles, and common fit mistakes. This is about better fit and better comfort—period.
AA / A Cup
AA and A cups typically benefit from shape + light support. If you want a smoother look under tops, a clean T-shirt bra works well. If you want a natural feel, unlined and wireless styles can be surprisingly flattering and comfortable.
B Cup
B cups often have flexibility across many styles. For daily wear, T-shirt bras give a clean silhouette. For low necklines, plunge bras are a great pick. For activity, sports bras help reduce bounce and improve comfort.
C Cup
C cups can feel “easy” in some bras and “off” in others—often due to shape (projection, fullness, spacing). If you get gaping at the top of cups, plunge or unlined styles frequently fit better. If you want smooth shaping under tops, start with a supportive T-shirt bra.
D Cup
D cup is where structure starts to matter more. A supportive band and stable cups make a big difference. If you want secure containment, full-coverage styles help. If you want a flattering neckline, plunge styles can lift without cutting in.
DD / E Cup
DD (sometimes labeled E) is extremely common—and also commonly mis-sized. If you’re spilling out of cups or straps are digging, you may need a smaller band and a larger cup (or a more supportive style). Full-coverage and full-figure bras often feel instantly better, and minimizers can create a smoother profile under fitted tops.
DDD / F Cup
DDD/F usually needs stable support: a firm band, supportive cup structure, and secure straps. Full-figure and minimizer styles reduce bounce and improve comfort, while unlined bras can feel lighter without sacrificing support when well-constructed.
G Cup
G cups typically need stronger features: wider bands, supportive wings, and cups that contain side tissue. If you feel weighed down, it’s often a band issue—sister size and choose full-figure or minimizer styles for immediate relief.
H / HH Cup
H/HH sizing exists because bodies exist. The right bra should feel stable and secure—without pain. Prioritize full-figure support and consider minimizers for a smoother profile under clothing. For activity, choose sports bras designed for containment.
Shop Bras by Need (Fast Picks That Usually Solve Fit Problems)
If you don’t want to overthink sizing, start with your goal. These categories help you pick the right bra faster.
Everyday & essential bras
Support & shaping
Sexy + specialty
Bra Size FAQ (Fast Answers)
The questions people ask right before they buy. These also help reduce returns.
What if I’m between two band sizes?
Start with the band that feels stable on the loosest hook without riding up. If you prefer a snug, supportive feel, choose the smaller band. If you want a softer feel, choose the larger band—then adjust the cup using sister sizing.
What if I’m between two cup sizes?
If you have spillage or cutting in at the top/sides, go up a cup. If you have gaping or wrinkling, go down a cup or switch styles (plunge and unlined often solve gaping).
Why do my straps dig into my shoulders?
Straps digging is usually a band/cup issue. If the band is too loose, straps carry too much weight. Try a smaller band (and a larger cup via sister sizing) or choose a more supportive style like full-figure/full-coverage bras.
What bra style is best for DD+?
Start with DD+ bras and full-figure/full-coverage bras for containment and lift. If you want a smoother profile under clothing, consider minimizer bras. For lightweight comfort, try an unlined bra built with good support.
Quick shop: DD+ Bras Full-Figure Minimizer
Should sports bras be tighter?
Sports bras should feel supportive and reduce bounce, but not restrict breathing. If you’re DD+, choose sports bras designed for containment and stable bands. If you feel pain, numbness, or can’t take a full breath, it’s too tight or the style isn’t right for your body.
Quick shop: Sports Bras
How often should I re-measure my bra size?
Re-measure every 6–12 months, and any time your body changes (weight shifts, pregnancy/postpartum, new workout routine, or if your current bras suddenly feel “off”).
Where do I start if I don’t know my bra size at all?
Measure underbust and bust, use the difference chart to estimate cup, then confirm with the fit checklist. If you want the easiest starting point, choose an everyday T-shirt bra or a full-coverage bra for DD+ comfort.
Quick shop: T-Shirt Bras Full-Coverage
Disclaimer: Sizing can vary by brand, fabric, and design. Use measurements as a starting point and confirm with fit checks. When a product page includes a specific brand sizing note, follow that first.
Ready to Shop the Right Fit?
Use your measurements as your foundation, then pick the bra style that matches your goal. Start here: