Find your bra size without a tape measure

Two quick ways to estimate your size: from a bra you already own, or from your clothing size. Both are estimates, and measuring gives a far more reliable result.

Estimating from a bra you own

This is the more useful of the two. Your current bra is a real starting point, and how it fits shows which way to adjust:

A band that feels loose, or rides up your back, is usually too big. We go down a band and up a cup letter to keep the same cup volume.
A band that is tight even on the loosest hook is too small, so we go up a band.
Cups that overflow are too small. Cups that gape may be too big, or may simply be the wrong shape for you.

Every rule is published on our methodology page.

Estimating from your clothing size

Dress sizes map only loosely onto bra bands, so we show a wide spread of bands for each dress size. If you add the cup letter you usually wear, we suggest sizes across that spread that keep the same cup volume. Treat these as sizes to try, not as your size.

Measuring without a tape measure

You can measure with a piece of string, ribbon or a phone charging cable: wrap it where the tape would go, pinch the point where it meets, then lay it flat against a ruler or metre stick. Then enter the numbers in the calculator.

Frequently asked questions

It is a rough starting point. The estimate from a bra you own is more useful than the one from clothing size, because it starts from a real bra and adjusts using how it fits. Neither is as reliable as four tape measurements.

Dress sizes are cut for bust, waist and hips rather than ribcage, so people who wear the same dress size can wear quite different bands. We show a deliberately wide spread rather than pretending to be precise.

The loosest. Bands stretch as they are worn, so starting on the loosest hook lets you move tighter as the bra ages. If a new bra only feels firm on the tightest hook, the band is too big.

Yes. Wrap string, ribbon or a charging cable where the tape would go, pinch the point where it meets, then lay it flat against a ruler. It is less precise than a soft tape, but far closer than an estimate.

Explainer guides

How to measure

The four measurements, step by step, with diagrams.

Common measuring mistakes

The errors that most often give the wrong size..

More sizing tools

Bra Size Calculator

Four measurements, both band methods, sister sizes and a confidence score.

Nursing Bra Calculator

Find your bra size through pregnancy and breastfeeding.

Bra size converter

UK, US, EU, FR and AU sizes side by side.

Cup volume comparison

Which of two sizes holds more, and why.

Fit diagnosis

Tick your fit problems, get a specific size to try.

Size tracker

Track size changes over time, stored only on your device.

Sister size calculator

Every size with the same cup volume, and when to try each.

Plus Size Bra Calculator

Find the right size for larger bands and fuller cups.

Strapless Bra Size

Find the firmer band size a strapless bra needs for a secure fit.

Sports Bra Calculator

Find the right size and support type for your activity.