oh my measure
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105H bra size

A 105H bra is cut for an underbust of 102.5–107.5 cm and a bust of 131–133 cm. Below it is the same size as every other system prints it, and the sister sizes that hold the same cup.

105H in every system

EU
105H
RU
105H
US
46H
UK
46FF
FR
120H
IT
8H
JP
105H

Where each notation comes from

What each notation means — why the British band reads 34 and the Italian reads 2 — is set out system by system on the bra size page.

Sources

Nothing here is looked up in a table of equivalents: band and cup are computed once from the metric ladder, then printed in each system’s own letters (formula version 2).

  • en.wikipedia.org the underbust ladder in 5 cm steps and the AA–H cup table
  • en.wikipedia.org the British and American cup runs, the French +15 shift, the Italian numbering
  • en.wikipedia.org the "+0" and "+4" methods, sister sizes, measuring upright and leaning forward
  • ru.wikipedia.org the Russian table: the same intervals, the same letters

Checked: no date on record

Where these numbers come from

The band is the underbust rounded to the nearest five centimeters, so 102.5–107.5 cm all round to 105. The cup is how far the bust exceeds that band’s nominal value: 26–28 cm gives this letter, at two centimeters per letter starting at ten. Add them and you get a bust of 131–133 cm.

The cup is measured against the nominal 105, not against the tape. That is what every published chart does, and it is why an underbust at the bottom of this band and one at the top get the same letter despite five centimeters between them. Near a band edge, try the sister size too.

In inches, 105H is an underbust of 40.4–42.3" and a bust of 51.6–52.4". Note that the UK and US band number is not that measurement: 105 cm is 40.4–42.3", and the band is called 46FF because the English notation adds four inches.

Same cup as 105H, different band

One band up is one letter down, because the cup is measured over the band — which makes 100I, 110G the same volume as 105H. In a shop the printed size that fits is routinely not the one the tape said, so these are worth trying on.

One step away

105G, 100H, 110H — a letter either side of 105H on this band, and this letter on the neighbouring bands.