Where the tape goes
Directly beneath your breasts, on the ribcage, where the bottom edge of a bra band would sit. It should be touching the crease under the breast, not an inch or two lower on your waist side of it.
If your breasts rest on your ribcage, lift them with one hand or lean forward a little while you position the tape, so that it lies underneath the tissue on the ribs themselves.
Step by step
- Undress to the waist and stand side-on to a mirror.
- Wrap the tape around your ribcage under the bust and bring the ends together at the front.
- Check it is level. Look in the mirror. The tape should be parallel to the floor, and no lower at the back than at the front.
- Breathe out normally and relax your shoulders.
- Pull the tape snug. Flat to the skin, firm, not biting in.
- Read the number to the nearest quarter inch or half centimetre. Write it down unrounded.
- Do it again. If the two readings differ by more than half an inch, take a third and use the two that agree.
Snug, tight and loose: what the difference tells you
The snug measurement is the one that sets your band. Two more readings can help if you fall between sizes.
| Reading | How | Use |
|---|---|---|
| Loose | Tape resting on the skin, just short of slipping | The upper limit for your band |
| Snug | As firm as a comfortable bra band | Your band measurement |
| Tight | As tight as you can pull, breath fully out | Shows how much your ribcage compresses |
If your tight reading is two inches or more below your snug one, you have room for a band to settle in, and when you are between sizes the smaller band will usually work. If the two are within half an inch, the tape is on bone, and the larger band is the kinder choice. This is the idea behind the six-measurement method described in our ABraThatFits explainer.
Mistakes that add or remove inches
- The tape slopes down at the back. The most common error. A diagonal path is longer, so the reading comes out too big.
- Measuring too low. The ribcage usually widens or narrows below the bust line. Keep the tape up against the breast crease.
- Holding a deep breath. Adds an inch or more.
- Measuring over clothes or a bra band. Fabric and elastic both add to the number.
- A twisted or stretched tape. Check an old tape against a ruler.
- Adding inches afterwards. Use the number as measured.
Turning the number into a band
Round your snug reading to the nearest even number. A 29¾ is a 30, a 32¼ is a 32. If you land on an odd number, you are between two bands. The table and the tie-break advice are in what band size am I?
Next, take the other half of your size with how to measure your bust.
Frequently asked questions
Should I measure my underbust breathing in or out?
After a normal, relaxed out-breath. Measuring on a full in-breath adds up to an inch or more and gives a band that is too loose. Forcing all the air out gives a number too small to wear comfortably.
How tight should the tape be?
Snug: flat against the skin all the way round and firm enough that it would not slide down, without making a dent. It should feel about as firm as you would want a bra band to feel.
Can I measure my underbust with a bra on?
Bare skin is best. If you keep a bra on, lift the band out of the way so the tape lies on your ribcage and not over the elastic or the wires.
Not measured recently? It takes two minutes.
Open the bra size calculator →