Why Your Bra Size Changes Between Brands (Charts Compared)
Your body has one measurement, but brands cut to different fit blocks, so the same printed size varies in cup depth, band elasticity and wire width. Victoria's Secret runs shallower and stretchier than Freya at identical labels. That is why your size seems to change between shops, and why a measured size beats a remembered one.
None of this is a conspiracy. It is what happens when there is no enforced international standard and each house drafts patterns for the customer it thinks it has.
What actually differs between brands
Three things, and none of them appear on the label. Cup depth: how far the cup projects from the chest wall at a given letter. Band elasticity: how much the band stretches under load, which decides whether a 34 band measures 30 inches relaxed or 33. Wire width: how wide the underwire sits, which has to match your breast root, not your cup size.
A brand that cuts shallow cups with a stretchy band will feel comfortable in the fitting room and unsupportive by month three. A brand cutting deep cups with a firm band feels strict at first and holds up for a year. Both can print 34DD on the tag.
The major names, and how they run
These are patterns commonly reported across fittings and reflected in each brand's own published charts. Individual styles within a brand still vary, so treat them as a starting bias rather than a rule.
| Brand | How it runs | Starting size advice |
|---|---|---|
| Victoria's Secret | Cups about half a size shallow, bands stretch generous | Between cups, take the larger; consider a band down |
| Skims | Compressive stretch fabrics, bands feel a size firm | Consider a band up for lounge styles |
| Freya / Fantasie | True UK sizing, deep cups, firm bands | Use your measured UK size as-is |
| Marks & Spencer | True UK sizing, slightly generous unlined bands | Measured size; band down in unlined cotton |
| ThirdLove | True to size, half-cup sizes available | Use half cups if your difference sits between inches |
| Bravissimo | D-K specialist, projected deep cups | Projected shapes: measured size. Shallow shapes: cup down |
| Chantelle | French sizing, shallow to average depth | Convert to FR sizing, expect a shallower cup |
| Savage X Fenty | Snug bands, shallower cups than UK brands | Sister size up in the band if between sizes |
How to read any brand chart in thirty seconds
Ignore the letters first and find the centimeters. Every legitimate chart maps a band label to an underbust range, and that range is the honest part. If a brand says its 34 band fits a 74 to 78 cm underbust and you measure 79, you are a 36 in that brand regardless of what you wear elsewhere.
Then check whether the chart adds inches to the underbust. Some legacy charts still tell you to add four or five, which will size you up a band and down a letter compared to the modern method. If a chart says to add, subtract it back out and use the raw measurement.
- Find the underbust range in centimeters, not the letter.
- Check whether the chart adds inches; if it does, ignore the addition.
- Compare the brand's bust range for your letter against your own bust measurement.
- When two sizes overlap, pick the firmer band and the roomier cup, then run the fit checks.
The practical routine
Measure once, properly, and keep the numbers in your phone. Convert to the brand's system before shopping, since a UK-cut brand and a US mall brand describe your cup differently past DD. Order your measured size plus one sister size when a retailer offers free returns; the second bra costs nothing and answers the band question in five minutes.
Our brand decoder does the translation step for ten major labels, and the global converter handles any size across all seven systems if you are shopping outside your home market.
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Written by the BraSizeConversion fit team. Last updated August 2026.