Understanding 40DD Bra Size
A 40DD bra size is considered a medium band size with an extra full cup size. This size is perfect for people with an average frame and extra full breast volume. Let's explore what makes this size unique and how to find the perfect fit.
Is 40DD considered big or small?
Fast facts about 40DD
- Snug 40 band with a 5-inch cup jump.
- Standing bust around 44.5–45.5 in keeps the cup filled.
- Share cup volume with 38E, 42D for band tweaks.
- Always scoop-and-swoop and check the gore for a flat anchor.
How 40DD is measured
Band fit
Aim for a snug 38.5–39.5 in underbust so the 40 band stays level without digging.
Cup depth
Standing bust in the 44.5–45.5 in range keeps roughly a 5-inch cup difference.
Support focus
Choose firm wings, fully adjustable straps, and swap sister sizes if the band shifts during wear.
40DD bust size in inches
| Measurement | Typical inches | How to capture it |
|---|---|---|
| Snug band (ribcage) | 38.5–39.5 in | Measure firmly under the bust on an exhale, then round to the band label. |
| Standing bust | 44.5–45.5 in | Keep the tape level across the fullest point while standing tall. |
| Band-to-bust difference | ≈5 in | Subtract your snug band from the standing bust to confirm cup depth. |
| Approx. cup depth | 6.5–7.5 in | Measure from the underwire root to the apex on a well-fitting bra. |
40DD bust size in centimeters
| Measurement | Typical cm | How to capture it |
|---|---|---|
| Snug band (ribcage) | 97.8–100.3 cm | Measure firmly beneath the bust, then map it to EU/FR/JP band labels. |
| Standing bust | 113–115.6 cm | Keep the tape level across the fullest point without compressing tissue. |
| Band-to-bust difference | ≈12.7 cm | Use the difference to double-check your metric cup depth. |
| Approx. cup depth | 16.5–19.1 cm | Trace from underbust to apex on a supportive bra to check projection. |
- Falls inside the 32-36 band range most people wear, giving a familiar fit baseline.
- Carries more volume than a standard D cup, so it can look prominent on petite bands.
- Monitor posture and band tension—small shifts change how the size looks.
- Try sister sizes 38E, 42D to fine-tune band tension.
Quick reference for 40DD
- 40DD ≈ band 40 label with a 5-inch cup step.
- Projected bust lands around 44.5–45.5 in.
- Use the calculator to convert this size across US/UK/EU/JP systems.
Ranges are approximations—double-check your own measurements for precision.
40DD across popular sizing systems
Match US 40DD to the most searched regional labels without leaving this guide.
Currently showing the United States (US) label — copy 40DD to match tags instantly.
United States (US)
40DD
United Kingdom (UK)
40DD
Europe (EU)
90E
France (FR)
105E
Japan (JP)
95E
Australia (AU)
18DD
Quick converter
Switch systems and copy the exact label for checkout forms or bra tags.
Need step-by-step help? Jump into the dedicated guides below for measurement nuances and shopping tips.
Perfect For
- Average frames
- Medium ribcages
- Extra full breast volume
- Premium support needs
Recommended Styles
T-Shirt Bras
Perfect for everyday wear under fitted clothing
- Seamless
- Molded cups
- Comfortable
Balconette Bras
Great for creating a natural lift and shape
- Wide-set straps
- Lower cut cups
- Enhancing
Plunge Bras
Ideal for low-cut tops and dresses
- Deep V-neck
- Minimal coverage
- Versatile
How 40DD tends to look
40DD pairs a 40-band with a 5-inch cup jump, so the silhouette changes with your frame and bra style.
- Keep 38E, 42D in mind—they share cup volume while tweaking the band.
- Shape, strap placement, and fabric choice all influence whether the size looks subtle or bold.
40DD compared with nearby sizes
Quick reference when you’re deciding whether to change the band, the cup, or both.
- 40D is one cup shallower—switch when 40DD wrinkles along the neckline.
- 40E adds depth while keeping the band snug if you spill out of 40DD.
- 38E / 42D keep the same cup volume but tweak band tightness for comfort.
Sister size playbook
- Try 38E when you need tighter or looser band support.
- Try 42D when you need tighter or looser band support.
Fit checks before you buy
When trying on 40DD bras, look for these key fit indicators:
- The band should fit snugly around your ribcage
- Cups should fully contain your breasts without spillage
- Straps should stay in place without digging in
- The center gore should lie flat against your chest
- Keep the band parallel to the floor on the middle hook.
- Scoop and swoop tissue into the cups before checking the gore.
- Adjust straps for lift, then reassess comfort after an hour of wear.
Remember that fit can vary between brands and styles. Always try on bras before purchasing to ensure the perfect fit.
Common 40DD questions
What size is 40DD in other systems?
40DD converts to 40DD in UK sizes, 90E in EU, 105E in FR, 95E in JP, and 18DD in AU.
What does 40DD mean?
40DD pairs a 40 band with a cup that is roughly 5 inches deeper than the band measurement.
Which sister sizes match 40DD?
40DD shares cup volume with 38E, 42D. Use them to tighten or relax the band.
How can I confirm this is my best fit?
Measure snug and standing bust, check for smooth cup edges, and ensure the band stays level after a few minutes of wear.
Check 40DD with our tools
Measure with the calculator, compare sister sizes, and review the perception guide for styling tips.