You don’t need a tailor’s tape to find a bra size. Anything that wraps around the body without stretching, plus something to read it against, gives the same two numbers.
What you need
- Something to wrap: a ribbon (best, because it lies flat), a piece of string, a shoelace or a phone charger cable. Nothing elastic.
- Something to mark it: a pen, a safety pin or a small piece of tape.
- Something to read it against: a ruler, a yardstick, or our printable measuring tape.
Step 1: the band
- Stand straight, arms relaxed, wearing a thin unpadded bra or no bra.
- Wrap the ribbon snugly around your ribcage, just under the bust.
- Check in a mirror that it is level all the way round, including at the back.
- Breathe out normally and mark where the end meets the ribbon.
- Lay it flat along the ruler and read the length up to the mark.
If the ribbon is longer than the ruler, measure it in sections: mark the ruler’s length, move the ruler along, and add the pieces together.
Step 2: the bust
- Wrap the ribbon loosely around the fullest part of the bust. It should touch without pressing in.
- Keep it level, and mark where it meets.
- Read it against the ruler the same way.
Measure twice and use the average. A ribbon slips more easily than a tape, so two readings are worth the extra minute.
Step 3: turn the numbers into a size
Enter both numbers into the bra size calculator, in inches or centimeters. It rounds the band, works out the cup and gives your size in every country’s system, with sister sizes.
To do it by hand: the snug underbust, rounded to an even number, is the band. The difference between bust and band in inches is the cup: 1 inch is an A, 2 a B, 3 a C, 4 a D, 5 a DD. The measuring guide covers odd numbers and rounding.
No ruler at home?
- Print one. The printable measuring tape prints true to size on US Letter or A4. Check the test square before you trust it.
- Use paper as a ruler. A US Letter sheet is 11 inches long; an A4 sheet is 29.7 cm. Mark the ribbon in sheet lengths and add them up. It’s rougher, but close enough for a starting size.
Common mistakes
- A stretchy ribbon or hair tie. It reads short. Use something that doesn’t stretch.
- Measuring over a padded bra. Padding adds to the bust measurement and gives too big a cup.
- Letting the band measurement drop at the back. A tilted loop reads long and gives too big a band.
- Pulling the bust measurement tight. It should rest on the body, not squeeze it.
If your breasts are soft or sit lower, add a leaning measurement too. See how to measure without a bra.
Sources & method: sizing rules follow the standard band-and-cup system used by UK, US, AU and EU brands, checked against fitting guides from specialist retailers and fitting communities. How we work.