How to measure a bra
Every point, drawn on the garment so there is no guessing where the tape goes.
Quick answer
Lay the bra flat and measure four points in fit order: underbust band, cup height, cup width and strap height. The band is taken across one flat layer and doubles to the body underbust, the anchor most listings skip. The cup is a shaped panel, not a doubled number. Hover or tap each step on the diagram.
Anyone buying a bra checks the band first, because it carries the weight and decides whether the whole thing sits level. After that comes the cup, and the strap that fine-tunes the lift. Most guides stop at band and cup. This page draws all four points on the actual garment, including the cup as a real shaped panel rather than a flat width you can double.
- A
Underbust
The band, taken straight across the bottom edge of the bra on one flat layer, directly under where the cups sit. Tap this step to see the exact line. The band carries most of the support, so it leads the fit.Double it for the full underbust (band) circumference.
- B
Cup Height
Run the tape along the cup from the band seam up to the top edge, following the curve of the molded panel rather than pressing it flat. Tap the step to see where the line starts and ends. This sets how much vertical volume the cup holds.Recorded as-is along the cup panel. Do not double.
- C
Cup
The cup width, taken across the widest part of the shaped panel from inner edge to side seam. Because a cup is a 3D piece, this is a panel measurement and not a flat number you can double into a body size. The diagram shows the exact span.Recorded as-is across the cup panel. Do not double; cup size comes from bust minus band.
- D
Strap Height
A single linear run along the shoulder strap, measured slack from the cup top to the back band. Tap the step for the exact path. Adjustable straps shift the lift, so this is the number a buyer checks against their own torso.Recorded as-is along the strap. Do not double.
Measure flat and never stretched, which matters double for a bra because the band and straps are elastic and will lie to you under tension. Smooth the band on one layer, let the cup hold its molded shape, and lay the strap slack. Of these four, only the underbust band is an across measurement that doubles to a body number. Cup height, cup width and strap height are read as-is, and cup size itself comes from the bust-minus-band difference, not from doubling any flat reading.
Bra size reference
| Size | Underbust | Cup Height | Cup | Strap Height |
|---|---|---|---|---|
| 32B | 13 | 6 | 5.5 | 13 |
| 34B | 14 | 6.25 | 5.75 | 13.5 |
| 36C | 15 | 6.75 | 6.25 | 14 |
| 38C | 16 | 7 | 6.5 | 14.5 |
| 40D | 17 | 7.5 | 7 | 15 |
Frequently asked
What bra size am I from these measurements?
Two body numbers set it: your underbust (the band) and your fullest bust. The band gives the number, like 34 or 36, and the difference between bust and band gives the cup letter, roughly one inch of difference per cup. So a 36 inch bust over a 32 inch band is about a four-inch difference, near a D cup on a 32 band. For the full sizing math and a US, UK and EU breakdown, use our bra size calculator or the bra size conversion chart.
Do I double the band measurement on a bra?
Yes for the band only. The underbust is taken across one flat layer, so the body circumference is roughly double the flat number. Cup height, cup width and strap height are not doubled; they are read along or across the piece as-is. Listing the flat band lets a buyer check it against a bra they already own.
Why can't I just double the cup measurement to get a cup size?
Because a cup is a molded, three-dimensional panel, not a folded flat tube. Doubling a flat cup width gives you a meaningless number. Cup size is defined by the gap between the bust circumference and the band circumference, not by any single flat reading of the garment, which is why the cup steps here are panel measurements you record as-is.
How do I measure a bra band that has stretched out?
Measure it relaxed on one flat layer without pulling, then note that a worn elastic band reads larger than new. For resale, measure what the band actually is now and say so in the listing. Buyers care more about the honest current band than the original tag size, since elastic loses tension with washing and wear.
Should I list bra measurements in inches or centimeters?
List both if you sell across markets, since band and bust sizing differs between US, UK and EU systems and a buyer thinks in the unit they grew up with. Stay consistent and label every number. Sizely shows both units on every chart so no buyer has to convert the band or cup in their head.
Where exactly is the underbust measured on the bra?
Straight across the very bottom edge of the band, right where it would sit under the bust on the body, with the bra flat and the elastic relaxed. Measuring higher catches the cup wires and reads too wide. Hover or tap the underbust step on the diagram to see the exact line.
Related size charts & tools
Bra size conversion chart
Bra size calculator
Women's international size chartSources: Sizely garment engine, spec #157 (Bra), four named measurement points. EN 13402 body-dimension sizing for bust and underbust (representative ranges only). Last verified June 2026.
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