40D bra size
40D names band 40 and cup D, with the cup marking a 4 in difference between your bust and band, rounded to whole inches.
US 40D · UK 40D
- Difference4 in10.2 cm
- Underbust, underbust method39 to 41 in99.06 to 104.14 cm
- Bust for this cup43.5 to 44.5 in110.49 to 113.03 cm
Each range includes its first figure and stops just short of its last.
Which measurements give a 40D
The label is a band and a cup, not a body measurement. Each of the three published rules turns the same label into different measurements.
| Method | Underbust (in) | Underbust (cm) | Bust (in) |
|---|---|---|---|
| Underbust method | 39 to 41 in | 99.06 to 104.14 cm | 43.5 to 44.5 in |
| Add-4 method | 34.5 to 36.5 in | 87.63 to 92.71 cm | 43.5 to 44.5 in |
| EU method, band 90 | 34.45 to 36.42 in | 87.5 to 92.5 cm | Cup read in cm |
Each range includes its first figure and stops just short of its last.
40D in six sizing systems
| System | Band | Cup | Size |
|---|---|---|---|
| US | 40 | D | 40D |
| UK | 40 | D | 40D |
| EU | 90 | D | 90D |
| FR/BE | 105 | D | 105D |
| AU/NZ | 18 | D | 18D |
| JP | 90 | E | 90E |
Bands and letters are label equivalents, not body measurements. JP letters vary by brand.
Sister sizes of 40D
A sister size moves the band one step and the cup one letter the other way.
- 2 bands down36DDD
- 1 band down38DD
- 1 band up42C
- 2 bands up44B
For 40D, a bust from 43.5 to 44.5 in falls in the range for cup D under both the underbust method and the add-4 method. The range’s upper endpoint is excluded.
Published charts disagree on the underbust that leads to band 40: the underbust method uses 39 to 41 in, while the add-4 method uses 34.5 to 36.5 in. These ranges do not overlap, so no underbust maps to 40 through both methods. The EU method gives the same body range band 90 from 87.5 to 92.5 cm.
The methods start from different measurements: the underbust method takes underbust directly, the add-4 method rounds it before adding according to its rule, and the EU method uses centimetres with bands spaced every 5 cm. The 40D label therefore depends on which method is used.
Questions
What does 40D mean?
40D is a band of 40 with a cup that stands for a difference of 4 in (10.2 cm) between bust and band in US sizing.
What measurements give a 40D?
By the underbust method, an underbust of 39 to 41 in (99.06 to 104.14 cm) gives band 40, and a bust of 43.5 to 44.5 in gives this cup. By the add-4 method, band 40 comes from an underbust of 34.5 to 36.5 in. Each range includes its first figure and stops just short of its last.
What are the sister sizes of 40D?
The sister sizes of 40D are 36DDD, 38DD, 42C and 44B. Each step up in band takes the cup one letter down, and each step down takes it one letter up.