How to Measure Your Bra Size

Getting your bra size right starts with two things: a soft measuring tape and the right base layer.

1. Wear a non-padded bra – something lightly lined that shows off your natural shape without adding volume.

2. To find your band size, wrap the tape snugly around your ribcage, just under the bust. It should sit flat and firm, parallel to the floor. This number, in inches, is your band size. If it’s an odd number, round up to the nearest even.

3. To find your overbust, measure around the fullest part of your bust, keeping the tape relaxed but level.

4. To find your cup size, subtract your band size from the overbust measurement – each inch difference equals one cup (1 inch = A, 2 inches = B, and so on).

That’s how to measure bra cup size at home. Say goodbye to dressing room drama – and hello to a better fit in just a few easy steps.

A bra that fits well should feel like a second skin – barely there, but totally supportive. The band is the foundation: it should hug your ribcage firmly without pinching, sitting straight and level all around. If you can slip two fingers underneath with ease, the fit is spot on.

Straps should stay put without digging in – remember, they’re there for a little lift, not to do all the work. Cups should cradle your shape smoothly, no gaping or spilling, no awkward wrinkles or bulges. And the centre front? It should lie flat against your chest – if it’s floating, your cup is too small.

Still unsure? Book a bra fit service at M&S and let an expert take the guesswork out of it.