UK bra sizes explained: cup order, sister sizes and how Tutti fits

By Beth Sables, Brand Manager
Updated: 13 October 2026

UK bra sizes combine a band number with a cup letter. The letters follow a set order and include double letters such as DD and FF. Cup letters aren’t a fixed volume: the same letter on a bigger band means a bigger cup. Both parts of your size matter.

Told you’re a 36C in one shop and a 34DD in another? No wonder ordering a new bra can feel like sitting an exam you didn’t revise for.

Let’s make those numbers and letters a little less mysterious, so you can spend more time choosing lovely lingerie and less time second-guessing the label.

Why are bra sizes different around the world?

No single sizing system is used by every lingerie brand worldwide. Different countries use different band numbers and cup lettering, so the same body can wear different size labels without changing shape at all.

Brands also develop their own patterns and fits. Fabric, cup construction and the style itself can affect how a bra feels, even when the label looks familiar. Our guide to why your size changes between brands explains more.

How do I work out my UK bra size?

Start with your under bust and over bust measurements, then use the brand’s sizing advice to find a starting size. Trying the bra on tells you whether that size and style work for your shape.

For help taking those measurements, follow our guide to how to measure your bra size at home.

One customer told us:

“So excited this set fit PERFECTLY. Just follow measurements.”

Five-star bralette review, 2026.

Measurements give you somewhere to start, but comfort gets the final say. Your band should feel secure, your cups should comfortably contain your bust, and you shouldn’t need to keep rearranging yourself throughout the day.

Your bra has a job to do. Constant supervision shouldn’t be part of it.

What order do UK cup sizes go in?

The cup sizes we stock, in order, are B, C, D, DD, E, F, FF, G and GG, with H, HH and J on some bands.

If you’re looking for UK bra sizes in order, this table shows the cup-letter sequence in Tutti’s range. Read down the table, keeping the band size the same.

The double letters belong in the sequence. Skipping DD or FF would mean skipping a cup-size option.

This is the range listed across Tutti’s size menu and filters, rather than a promise that every style comes in every size. Check the individual options when browsing our underwired bras.

Is a DD bigger than an E?

No. In UK sizing, E comes after DD, so on the same band an E is the next cup size up.

A 34E therefore has more cup capacity than a 34DD. Keep the band number in the comparison, because comparing letters alone won’t tell you which cup is bigger.

Some of our bralettes use grouped cup sizes, such as DD/E/F. That means one bralette size is designed to accommodate that cup range on the stated band. It doesn’t mean those individual bra sizes are identical.

As one customer explained:

“I’m a size 34F so ordered the 34DD/E/F and would say this is true to size.”

Five-star bralette review, 2024.

Other countries and brands can label the steps after D differently, which is why checking the sizing system matters.

Is a 36C bigger than a 34C, and what is a sister size?

Yes. A 36C has a larger band and more cup capacity than a 34C. The letter C doesn’t describe one fixed cup volume across every band.

Sister sizes are bra sizes with similar cup volume but different band sizes. They can help when the cup capacity feels right but the band fit needs adjusting.

Changing only the band number while keeping the same letter changes the cup capacity too. That’s why finding a sister size involves considering both parts of the label.

One customer shared:

“I sister sized to a 38FF/G and it’s great!”

Five-star lingerie set review, 2024.

A sister size is named in 7 of 3,721 customer reviews across all products, up to 5 October 2026

If your current bra almost fits, tell us what feels wrong before choosing another size. A loose band and a tight cup need different attention.

How do UK sizes compare with US and EU sizes?

UK and US bra sizes can look similar, but the cup lettering isn’t always interchangeable. EU labels can use different band numbers and a different cup sequence.

For UK cup size conversion, use our UK bra sizes chart and check the sizing information for the brand you’re buying.

If you’re converting American bra cup sizes to UK sizes, use both your band and cup. Don’t rely on a shortcut such as “go down two sizes”, because conversions and labelling can vary by brand.

The chart helps you interpret the label. The fit tells you whether the bra works for your body.

Is Tutti true to size, and should I size up or down?

There isn’t one size-up or size-down rule for every Tutti style. Start with your usual well-fitting UK size, then check the product’s fit advice and reviews.

Of 1,472 bra and bralette reviews, 72 say it's true to size, 37 say it runs small (or they sized up), and 31 say it runs big (or they sized down). These figures come from our customer reviews up to 5 October 2026.

One customer said:

“This bralette is true to size and as supportive as you’d expect from Tutti.”

Five-star bralette review, 2024.

Other feedback includes “the bands run way big” on some bralettes and “the cup sizing is quite small” on others. Those comments describe particular purchases, rather than the whole range.

Three Hallie reviewers advise sizing up. That’s worth considering alongside the product guidance, but it isn’t an automatic instruction for everyone. With our bestselling Gia, check the band and grouped cup options before choosing.

For a fuller bust, cup room and band security both matter. Curvy bodies deserve a comfortable fit, whatever combination of numbers and letters gets you there.

Can a fitting help me find my size?

Absolutely. Our 90-minute one-to-one fitting at our Earl Shilton HQ gives you time to try styles and talk through what feels right. The £20 deposit is refunded in full when you attend. 

Our bra fitting sessions are all about finding a bra that suits your body shape and feels comfortable. The size you measure isn’t always the best fit for you, so we focus on how the bra actually feels and sits on your body.

We don’t use a tape measure. Instead, we look at how the band and cups fit, then work with you to find the size and style that give you the support and comfort you deserve. Every body is different, but something we often see is a band riding up and cups that are too small. Customers have sometimes gone up a band size to make up for needing more room in the cups, without realising how this affects the overall fit.

We’ve been offering fittings at Tutti Rouge for over a year. During your 90-minute appointment, you can expect to try around nine different bra and bralette styles on average. Some customers even try on several bodysuits too, so there’s plenty of opportunity to explore what works for you.

The biggest change we notice? Confidence. When a customer finds a bra that fits properly and feels good, they often stand a little taller. That’s what our fittings are all about: helping you feel comfortable, supported and confident from the inside out. 

- Beth Sables, Brand Manager 

Bring your sizing questions, including the ones you think you should already know the answer to. That’s exactly what we’re here for.

Frequently asked questions

Are UK and US sizes the same?

Not always. The labels can look similar while the cup lettering differs. Check the brand’s conversion guide before ordering.

Does Tutti Rouge use UK sizing?

Yes, Tutti Rouge uses UK bra sizing. Our international size guide helps you find the corresponding size if you usually shop in another system.

Should I trust a conversion chart?

Use the chart provided by the brand you’re buying from as a starting point. Read the style’s fit advice too, because a conversion can’t account for every difference in shape or construction.

What should I do if I’m between sizes?

Ask for help with the specific style. Tell us your measurements, your current size, and whether the band, cups, or both feel wrong, rather than automatically sizing up.

Is a DD the same as an E?

No. In UK sizing, E is the next cup size after DD when the band stays the same. A grouped DD/E/F bralette size accommodates several cup sizes.

Ready to take the guesswork out of your next bra? Book a bra fitting (£20 deposit, refunded on the day).

Can’t make it to HQ? Email your under bust and over bust measurements to hi@starkersgroup.com and we can advise your guide size.