34DD Bra Size: Measurements, Sister Sizes and Your Size

Key Takeaways

• A 34DD fits an underbust of about 34 inches (86 cm) and a bust of about 39 inches (99 cm).
• The 34 is the band around your ribcage. The DD means your bust is about five inches bigger than that band.
• A 34D and a 34DD share the same band. The 34DD has one inch more room in the cup.
• The sister sizes of 34DD are 32DDD (UK 32E) and 36D. They hold the same cup volume on a different band.
• In EU sizing a 34DD is usually written as 75E.
• On Krvvy's size chart a 34DD is an XL.
• A 34DD and a 36C have the same bust measurement. The band is what tells them apart.

What is a 34DD bra size?

A 34DD is a bra for a ribcage of about 34 inches with a bust about five inches bigger, at around 39 inches. The number tells you the band. The letters tell you the cup, which is worked out from the gap between your two measurements.

Each cup letter adds about an inch to that gap. A 34A has a one-inch gap, a 34B two inches, a 34C three, a 34D four and a 34DD five. If you want the full picture of how those letters work, our guide to DD cup size covers every DD from 30 to 40.

34DD measurements in inches and cm

Measured in inches, a 34DD expects an underbust between 33 and 34 inches and a bust around 39 inches. In centimetres that is an underbust of roughly 84 to 86 cm and a bust of roughly 98 to 100 cm.

The underbust range starts at 33 because of how bands are rounded. Bands come in even numbers, so a snug underbust of 33 inches rounds up to a 34 band. If your underbust is 35 inches, you are closer to a 36 band, and a five-inch gap would then make you a 36DD instead.

The bust figure has a little give in it. Anything from about 38.5 to 39.5 inches over a 34 band still reads as a DD. Above 39.5 inches you move towards a 34DDD. Below 38.5 you move towards a 34D.

To measure, wear an unpadded bra or no bra. Pull the tape snug and level around your ribcage just under your breasts for the underbust, then measure loosely around the fullest part of your bust. Our step-by-step measuring guide shows where each tape should sit.

Is 34DD a big bra size?

A 34DD sits in the middle of the size range. The DD sounds large, but the band is a fairly common one, and the bust measurement of about 39 inches is the same as a 36C.

That comparison is useful. Many women think of a 36C as an everyday, middle-of-the-road size. A 34DD holds a similar amount of breast tissue on a band two inches tighter. The difference is in how the bra is built around your ribcage rather than in the size of your bust.

Whether a 34DD looks big or small on you also depends on your height, your frame and the shape of your breasts. The letters describe a measurement. They are not a description of your body.

34D vs 34DD: what is the difference?

A 34D and a 34DD have the same band. The only change is the cup, and it is a single step. A 34D expects a bust of about 38 inches. A 34DD expects about 39 inches.

In practice the 34DD cup is slightly deeper and wider. If you wear a 34D and feel the top edge of the cup pressing in, or notice breast tissue at the sides near your underarm, a 34DD may suit you better. If you wear a 34DD and see a gap at the top of the cup, a 34D may be the better fit, although cup shape can cause gaps too.

The 34DD is the bigger of the two. People often search for "which is bigger, 34D or 34DD" because the double letter reads like a smaller jump than it is. It is exactly one cup.

34DD vs 34DDD

The next cup up from a 34DD is a 34DDD in US sizing, or a 34E in UK sizing. It expects a bust of about 40 inches on the same 34 band, a six-inch gap.

This is where brands start to disagree. Some US brands use DDD and F for the same cup, while UK brands use E. If you are moving up from a 34DD, check the brand's own chart rather than assuming the next letter matches what you expect.

34DD sister sizes

Sister sizes hold the same cup volume on a different band. To find them, go down one band size and up one cup, or up one band size and down one cup.

For a 34DD, the sisters are 32DDD (written 32E in UK sizing) and 36D. A 32DDD has a tighter band and a deeper cup. A 36D has a looser band and an earlier cup letter, though the cup holds the same volume.

You might use a sister size when the cups fit but the band does not. If a 34DD band digs into your back, a 36D gives the same cups more room around the ribcage. If a 34DD band rides up, a 32DDD holds you more firmly. Sister sizing is best kept for small adjustments. Moving the band two inches looser means it carries less of the weight, which most women notice by the end of the day.

34DD in other sizing systems

A 34DD reads the same in UK and US sizing, since both systems agree up to DD. In EU sizing the band is measured in centimetres and there is no DD, so the cup after D is called E. A 34DD is usually written as 75E. French sizing adds 15 to the EU band, giving 90E.

Indian brands mostly use the same band numbers as the UK and US. Above D, cup labels vary from brand to brand. Enamor, Zivame, Clovia and PrettySecrets each publish their own charts, and it is worth reading each one before buying a 34DD from a new label.

What size is a 34DD at Krvvy?

Krvvy bras are sold in letter sizes, from M to 4X in most styles. On our bra size chart, the XL covers an underbust of 32.2 to 34 inches and a bust of 39 to 40.5 inches. A 34DD falls inside both ranges, so XL is your Krvvy size.

If your underbust is right at 34 inches or a little over, you sit close to the edge of the XL range. In that case, put both your measurements into Find My Size and check the product's own size chart before ordering, since stretch styles and moulded cups fit slightly differently.

What to look for in a bra as a 34DD

A firm, level band does most of the work. At 34DD the cups carry more weight than a C or D on the same band, so a band that stays put through the day matters more than any other feature. You should be able to slide two fingers under it, no more.

Look for cups deep enough to hold all of your breast tissue, side wings wide enough to stay flat and straps that sit without digging in. For long days, a bra built for fuller cups gives the most even hold. The Trueform Support Bra was designed for C to F cups and suits a 34DD for everyday wear.

For softer, all-day comfort, the Feel-Good Everyday Bra is seamless and sits smoothly under clothes. Under fitted shirts and T-shirts, the Flawless Fit T-Shirt Bra uses moulded cups and a soft underwire, which holds its shape and keeps lines from showing.

How to tell if your 34DD fits

Put the bra on using the loosest hook, since bands loosen with wear and you will move to tighter hooks over time. Lean forward and settle your breasts into the cups, then stand up straight and check a few things.

The band should sit level all the way round, not higher at the back. The centre panel between the cups should touch your chest. The top of each cup should lie flat with no cutting in and no gap. The wire or the bottom edge of the cup should sit behind your breast tissue at the sides, not on it.

If the band rides up, try a 32DDD. If the cups spill, try a 34DDD. If the band digs and the cups fit, try a 36D. Our guide to the signs you are wearing the wrong bra size explains each of these in more detail.

Frequently Asked Questions

What does 34DD mean in inches?

A 34DD fits an underbust of about 33 to 34 inches and a bust of about 39 inches. In centimetres that is roughly 84 to 86 cm under the bust and 98 to 100 cm at the fullest point. The five-inch gap between the two measurements is what makes it a DD.

What are the sister sizes of 34DD?

The sister sizes of 34DD are 32DDD, which UK brands call 32E, and 36D. Both hold the same cup volume as a 34DD on a different band. Use them when the cups fit well but the band feels too tight or too loose.

Which is bigger, 34D or 34DD?

A 34DD is bigger by one cup. Both have the same band, but a 34DD cup holds about one more inch at the bust. A 34D expects a bust of around 38 inches and a 34DD expects around 39 inches.

Is 34DD the same as 36C?

No, although they share the same bust measurement of about 39 inches. A 36C has a band two inches looser and a cup one step smaller. If a 36C band rides up your back while the cups feel full, a 34DD may fit you better.

What size is 34DD in Krvvy bras?

A 34DD is an XL in Krvvy bras. The XL range on Krvvy's chart covers an underbust of 32.2 to 34 inches and a bust of 39 to 40.5 inches. If you are at the edge of either range, use Find My Size before you order.

What is 34DD in EU sizing?

A 34DD is usually 75E in EU sizing. EU bands are measured in centimetres, and EU sizing has no DD, so the cup after D is called E. Always check the brand's own chart, since conversions vary slightly.