Sizing guide
Find your size. Measure once, follow the chart, and shop with more confidence. If something doesn't fit when you receive it, the first exchange is on us.
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Measure yourself
Start measuring ↓Walk through underbust, bust, waist, and hips. Takes about 3 minutes with a soft tape measure (or a piece of string and a regular ruler).
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See the size chart
Where to find chart ↓Already know your measurements? Skip straight to the size chart for bras, bodysuits, shapewear, and underwear.
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Take the size quiz
Start quiz →Five questions, sixty seconds. Best when you don't have a tape measure handy or you want a recommendation that accounts for fit preferences too.
Measure yourself in 4 steps
Use a soft tape measure. Snug but not tight — the tape should sit against your skin without compressing it. Wear an unpadded bra or no bra at all for the most accurate read.
Step 1 — Find your underbust
Step 2 — Mesure your bust
Step 3 — Define your waist
Step 4 — Find your hips
Wrap the tape directly under your bust, where the band of a bra would sit. The tape should sit horizontally — flat across your back, not riding up.
Breathe out, and read the measurement. Round to the nearest even number.That number is your band size.
Example: an underbust of 33" rounds to a 34 band.
Wrap the tape around the fullest part of your bust. Stay relaxed — don't lift, smooth, or compress.
Read the measurement, then subtract your band number from Step 1.
Each inch of difference is one cup size:
1 inch = A · 2 = B · 3 = C · 4 = D · 5 = DD · 6 = DDD · 7 = G
Example: 38" bust − 34" band = 4 inches = D cup. Your size is 34D.
If you're not sure between cups, you can size up the cup — it's a more comfortable margin than a cup that runs small.
Find the narrowest part of your torso — usually about an inch above your belly button.
Wrap the tape around it horizontally. Don't suck in — measure your natural waist, not a held-in one.
This number is your waist measurement. You'll need it for bodysuits, shapewear, and high-waist underwear.
Stand with your feet together. Wrap the tape around the fullest part of your hips and rear — usually 7 to 9 inches below your waist.
Read it horizontally. The tape should sit flat all the way around.
This number is your hip measurement, used for bodysuits, briefs, thongs, and shaping pieces.
You now have four numbers: underbust, bust, waist, hips. Take them to the size chart below.If you're between two sizes in any of them, see the "between sizes" guidance below the chart — we usually recommend sizing up for a softer fit.
Size charts
Bras (band + cup)
BAND SIZE — based on your underbust
Underbust (inches) → Band size
28–29" 30
30–31" 32
32–33" 34
34–35" 36
36–37" 38
38–39" 40
40–41" 42
42–43" 44
CUP SIZE — bust minus band
Difference (inches) → Cup
1" A
2" B
3" C
4" D
5" DD
6" DDD
7" G
Available combinations on ILARIA:
30D, 30DD, 30DDD, 30G
32D, 32DD, 32DDD, 32G
Bodysuits & shapewear
Size Bust (in) Waist (in) Hips (in)
XS 32–33 24–25 34–35
S 33–34 25–26 35–36
M 35–36 27–28 37–38
L 37–39 29–31 39–41
XL 40–42 32–34 42–44
2XL 43–45 35–37 45–47
If you're between sizes, we usually recommend the larger size for a softer fit.
Underwear & briefs
Size Waist (in) Hips (in)
XS 24–25 34–35
S 25–26 35–36
M 27–28 37–38
L 29–31 39–41
For high-waist styles, also check your waist measurement against the band rise on the product page.
International sizing
U.S. bras and EU bras measure differently. Use this rough conversion for reference, then double-check on the size chart of any brand you compare ILARIA to.
U.S. band → EU band: 30 → 65 · 32 → 70 · 34 → 75 · 36 → 80 · 38 → 85 · 40 → 90 · 42 → 95 · 44 → 100
U.S. cup → UK cup: A=A · B=B · C=C · D=D · DD=DD · DDD=E · G=FF
For alpha sizing (XS–2XL), most regions use the same letters but the inch/cm ranges vary. Stick to inches when comparing to ILARIA.
Between sizes? Here's what we recommend
Most ILARIA customers size up when they're between sizes — wireless bras feel softer at a slightly looser band, and shapewear stays comfortable longer when it isn't fighting you.
Three exceptions to the "size up" rule:
• Firm shapewear meant for events — keep your usual size to preserve the sculpted feel.
• If your underbust falls exactly on an even number (e.g. exactly 32"), go with that band — don't round up.
• If you've been wearing the wrong bra for a while and your current bras feel "fine," remeasure rather than going by what you wear today. Most women are wearing one band size too big and one cup size too small.
If it still doesn't feel right when you receive it — first exchange is free.
Sister sizes — for "close but not quite" fits
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Bra cup size isn't an absolute volume — it's a relationship to the band. A 34D and a 32DD hold almost the same amount of breast tissue. They're called "sister sizes" because they share cup volume but have different band sizes.If the cup of a bra feels right but the band is off, try a sister size before switching to a fully different combination.
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The rule:
• Go DOWN one band size → go UP one cup letter (keeps cup volume).
• Go UP one band size → go DOWN one cup letter.
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34D feels right in the cup but the band is too tight → try 36C.
34D feels right in the cup but the band rides up → try 32DD.
36DD fits the cup but the band is loose → try 34DDD.
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When NOT to use sister sizing:
• Cup gaps or spills but the band is fine → just adjust the cup, no band change.
• Both band and cup feel wrong → re-measure, or take the quiz.
If you've bought from us and the fit is off, the first exchange is free. Email us what didn't work and we'll recommend the right sister size for your next try.
Still not sure? Take the quiz