How to work out your real bra size (measuring tape not required)
Posted by Claire Hewitt, on May 21, 2026.
Estimated reading time: 7 minute(s)
Tips and tricks from an expert on measuring your true bra size in time for summer
Can you really determine someone’s bra size by sight alone? Well, professionally trained lingerie experts can. Marks & Spencer made headlines earlier this month when it announced that it was ditching the use of measuring tapes during bra fittings. Following a successful trial, a new hands-off approach is being rolled out across hundreds of M&S stores.
But this method isn’t completely new: experts in the lingerie industry, such as retailer and Royce stockist Bravissimo, already take a ‘look first’ approach when sizing up customers. Taking clues from the look and feel of the bra a customer is already wearing can tell an expert a lot about someone’s real bra size than just the numbers on a tape measure. Some customers might also feel more comfortable not having a stranger (however respectful) getting up close and personal with the measuring tools.
So how do the experts do it? Royce’s head of design Gemma de Diego confirms that with experience and the right guidance you really can gauge a woman’s bra size by eye. She shares how she does it, so you’re equipped with expert tips for refitting at home ahead of your summer wardrobe refresh.
How old is the bra?
Gemma asks the wearer not only what size bra they’re currently wearing, but also how old the bra is. “Over time fabrics give so you may notice the band is a little loose,” she says. Many of us are guilty of wearing bras that are well past their prime. One survey revealed that, on average, British women are wearing bras that are four years old or more. Despite guidelines recommending you get refitted every 12 months, or after any major physical changes (such as surgery, weight loss or pregnancy), many women leave it much longer.
Have a good look at all the bras in your underwear drawer. Any that are several years old and showing signs of wear, such as frayed elastane or overstretched straps and underband, it’s time to recycle them. Drop off unwanted underwear at a bra bank at any Royce stockist: this not only reduces landfill waste, but also helps raise money for the charity Against Breast Cancer.
Check the underband
This is the biggest clue that your bra doesn’t fit you, says Gemma, who often (discreetly) spots this problem on strangers when she’s out and about: “I often see a person’s underband ride up, which then causes the boobs to droop down. Contrary to what many people may think, most of a bra’s support comes from the underband. If it’s not even and straight across your back, then it’s not supporting your breasts properly.”
Digging in = Band is too small
Rising up = Band is too big
Straight across = Perfect Fit
The band should clasp comfortably on the middle hook and eye fastening, this gives you the option to loosen through the day if needed or tighten as the fabric gives with wear. On the middle fastening, when trying the bra for the first time, the underband should feel snug but not tight.
Examine the cups
“I look at whether the cups are digging in on the underarm and neck edge, or if they’re loose and the boobs aren’t filling them,” says Gemma. When at home, pop on your regular bra and look at your boobs in a mirror from all angles. Notice if they bulge over the top or if you can feel flat spots when you prod them. This will tell you if your current cup size is too big, too small or just right.
Bulging = Cups are too small
Gaping = Cups are too big
Evenly covered = Perfect Fit
Try on alternative sizes
Depending on whether your cups and underband are too big or too small, experiment with bras a size up or down. Follow the ‘sister sizing’ method which explains the magic formula behind this fitting trick. The mantra is: if you go down a size in the underband, you need to go up a size in the cup to keep the same cup capacity, and vice versa.
Find a fitter or follow our expert fit guide
If you can, it’s always worth spending time with a professional bra fitter, and Royce stockists offer some of the best bra fitting services around. The next best thing is to follow our ultimate DIY bra fitting guide – which includes handy pictures – to find your perfect bra size in the comfort of your own home.
Royce’s best bras for summer outfits
Polka dots, sporty ensembles, ‘80s colour blocking…whether or not you’re following any of summer 2026’s big fashion trends, we’re betting your day-to-day wardrobe will be full of summer staples: think loose fits in breathable fabrics, versatile summer dresses, and light or bright seasonal shades.
A ‘feel good’ outfit starts with the very first layer, so here are Royce’s top picks, from the best non-wired cotton bras for keeping cool, to the best fuller-cup bras for summer dressing.
Posie
Match this summer’s sporty trend to perfection with this athleisure-style wirefree T-shirt bra. Posie comes in a range of six colours, including blush pink and mocha, so it cleverly blends into skin tones under pale, thin fabrics. Available for A to D cups.
Comfi-bra
One of our best front-fastening bras is also non-padded and made with 98% cotton to keep your cool in warm weather. The high-quality, breathable cotton feels super soft, and the added elastane gives a slight stretch, resulting in a superbly comfortable wirefree summer bra. Available for B/C to D/DD cups.
Impact Free
For fuller cups, staying cool and supported in warm weather starts with the right bra. Made from 100% cotton, Impact Free is breathable, comfortable, and designed to keep you feeling fresh on sunny days. The high neckline and wide underband provide exceptional support up to a K cup, making it the perfect choice for long walks, active days, and everyday comfort in the heat.
Cara
Looking for an exceptionally supportive bra for fuller cups this season? Cara is the one. Years in the making, this comfortable bra offers full cup coverage, supportive side slings and is non-padded with cotton lined cups to keep you cool in a heatwave. Available in summer-friendly white and blush, alongside versatile black, and sizes G to L cup.
Mia
Our ultimate lounge bra is also one of our most relaxed and supportive bras for fuller cups (F to JJ). Made from super soft organic cotton, Mia is not only wirefree but also free from any fastenings or components. Featuring non-padded cups, wide straps and underband, Mia can also be worn as a cool sleep bra on hot summer nights.
Grace
Grace combines everyday comfort with a beautifully feminine finish. Made with a high cotton content, this soft and breathable bra is perfect for warmer days, while the delicate embroidery adds an elegant touch. Designed to offer reliable support and all-day comfort for B – FF cup, Grace is a feel-good favourite you’ll love wearing every day.
