Bras N Things to Marks & Spencer bra size
The short answer
Bras N Things 12D is Marks & Spencer 34D by the two brands' own charts.
Cups are counted along each brand's own letter order, and the band is carried across unchanged.
| Bras N Things | Bras N Things builds it for | Marks & Spencer, by chart | Same label | Marks & Spencer builds it for | Marks & Spencer also prints |
|---|---|---|---|---|---|
| 12A | not published | 34A | not published | not published | not published |
| 12B | not published | 34B | not published | not published | not published |
| 12C | not published | 34C | not published | not published | not published |
| 12D | not published | 34D | not published | not published | not published |
| 12DD | not published | 34DD | not published | not published | not published |
| 12E | not published | 34E | not published | not published | not published |
| 12F | not published | 34F | not published | not published | not published |
| 12G | not published | not made | not published | not published | not published |
What wearers say
Charts describe a garment. People who own both brands describe a fit, and their answer ranks above this table once five of them stand behind it. Pick your size in the converter to see whether there are enough yet.
Sources
- Bras N Things size guide, read on 2026-09-18.
- Marks & Spencer size guide, read on 2026-09-18.