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32DD Sister Size: US and UK Rows From Three Brand Charts

32DD sister sizes are 30DDD and 34D in US letters and 30E and 34D in UK letters, with the rows ThirdLove, Playtex and Harlow & Fox print for bands up to 48.

By Plus Size Edit9 min read

Cover card reading “32DD Sister Size: US and UK Rows From Three Brand Charts” over a dark red lace underwire bra laid flat on a white sheet

The 32DD in your drawer fits in the cups, but the band digs in by the afternoon, or the style you want starts at a 34 band. Going up to a 34DD feels like the fix, but it brings bigger cups too. Below are the sister sizes for 32DD and for larger bands up to 48, up to two sizes each way, in US and UK letters, as three brands’ sister size charts print them.

The short answer

Your size (US letters) One band smaller One band bigger
32DD 30DDD 34D
34C 32D 36B
34DD 32DDD 36D
34DDD 32G 36DD
36DD 34DDD 38D
38DD 36DDD 40D

All six pairs above sit in rows of ThirdLove’s sister size chart, which labels DD as E and DDD as F. On Harlow & Fox’s UK chart, 32DD’s two sisters are 30E and 34D.

What a sister size keeps

A sister size keeps the cup volume and moves the band: one band smaller and one cup letter bigger, or one band bigger and one letter smaller. Bands go up in twos on the ThirdLove, Playtex and Harlow & Fox charts, so one step is 32 to 34.

The letter alone is not a volume. On Harlow & Fox’s sister size guide, “A 38DD will be one cup size larger than a 36DD, which is in turn one cup size larger than a 34DD”. So 34DD is the wrong answer for a 32DD band that digs in: the cups grow with the band. On the same guide’s chart, 32DD shares a row with 34D.

Which way to move: check the band, not the tape

  1. Start from a bra whose cups fit. If nothing fits yet, measure first; the tape method is in how do i measure my bra size.
  2. Note which hook it is on. ThirdLove’s guide puts the test in one line: “Sister size up when your band is tight on the loosest hook, and sister size down when it’s loose on the tightest hook.”
  3. If the cups are wrong too, a sister size is the wrong tool. The same guide: “If your band fits but your cups don’t, change only your cup size instead of switching to a sister size.”
  4. Move one step first. The second step in each table is for when the first is not made in your style.
A cloth tape measure unrolled across the edge of an old wooden table in warm light
Photo: Jahra Tasfia Reza / Pexels

DD, DDD, E and F: which letters are you reading?

  • DD is DD in US and UK letters. Harlow & Fox’s conversion chart puts a UK DD next to a US DD/E.
  • The next cup is DDD in US letters and E in UK letters. That chart puts UK E next to US DDD/F. ThirdLove’s chart “uses Thirdlove cup letters, where DD equals E and DDD equals F”, and in Glamorise’s cup calculator a difference of 6 is “DDD, or F”.

So E and F name different cups in the two systems, and ThirdLove’s chart image labels its G cups DDDD; the letter-by-letter conversion is in bra size conversion chart. That is why 32DD’s smaller sister is 30DDD in the US table below and 30E in the UK one: same bra, two names.

US sister sizes as ThirdLove and Playtex print them

The US table uses the letters of the row Harlow & Fox’s conversion chart labels US for DD and up (DD/E, DDD/F, G, H, I), written as DD, DDD, G, H, I. Every size in it is copied from ThirdLove’s chart, in its table (bands 30 to 42) or its chart image (bands 30 to 48), or from the Playtex 18 Hour chart that Target hosts (bands 30 to 48, cups A to DDD). A dash means neither chart prints that size in the row; the last column names the chart or charts the row’s sizes are printed on.

Your size Two bands smaller One band smaller One band bigger Two bands bigger Printed on
32DD — 30DDD 34D 36C ThirdLove, Playtex
34C 30DD 32D 36B 38A ThirdLove, Playtex
34DD 30G 32DDD 36D 38C ThirdLove, Playtex
34DDD 30H 32G 36DD 38D ThirdLove, Playtex
36DD 32G 34DDD 38D 40C ThirdLove, Playtex
36DDD 32H 34G 38DD 40D ThirdLove, Playtex
36G — 34H 38DDD 40DD ThirdLove
36H — — 38G 40DDD ThirdLove
38DD 34G 36DDD 40D 42C ThirdLove, Playtex
38DDD 34H 36G 40DD 42D ThirdLove, Playtex
38G — 36H 40DDD 42DD ThirdLove
38H — — 40G 42DDD ThirdLove
38I — — 40H 42G ThirdLove
40DD 36G 38DDD 42D 44C ThirdLove, Playtex
40DDD 36H 38G 42DD 44D ThirdLove, Playtex
40G — 38H 42DDD 44DD ThirdLove
40H — 38I 42G 44DDD ThirdLove
42DD 38G 40DDD 44D 46C ThirdLove, Playtex
42DDD 38H 40G 44DD 46D ThirdLove, Playtex
42G 38I 40H 44DDD 46DD ThirdLove
44DD 40G 42DDD 46D 48C ThirdLove, Playtex
44DDD 40H 42G 46DD 48D ThirdLove, Playtex
46DD 42G 44DDD 48D — ThirdLove, Playtex
46DDD — — 48DD — Playtex
48DD — 46DDD — — Playtex
Source: ThirdLove sister size chart (table, and chart image transcribed by hand); Playtex 18 Hour sister size chart hosted by Target · read 1 Oct 2026

UK sister sizes as Harlow & Fox prints them

Harlow & Fox’s sizing guide says the brand uses UK sizing, and gives the generally used cup order as D, DD, E, F, FF, G, GG, H, HH and on. Its sister chart runs bands 28 to 40 and cups to H; every size below is copied from it, and a dash means the chart stops before that size.

Your size Two bands smaller One band smaller One band bigger Two bands bigger Printed on
32DD 28F 30E 34D 36C Harlow & Fox
34C 30DD 32D — — Harlow & Fox
34DD 30F 32E 36D 38C Harlow & Fox
34E 30FF 32F 36DD 38D Harlow & Fox
36DD 32F 34E 38D 40C Harlow & Fox
36E 32FF 34F 38DD 40D Harlow & Fox
36F 32G 34FF 38E 40DD Harlow & Fox
36FF 32GG 34G 38F 40E Harlow & Fox
36G 32H 34GG 38FF 40F Harlow & Fox
36GG — 34H 38G 40FF Harlow & Fox
38DD 34F 36E 40D — Harlow & Fox
38E 34FF 36F 40DD — Harlow & Fox
38F 34G 36FF 40E — Harlow & Fox
38FF 34GG 36G 40F — Harlow & Fox
38G 34H 36GG 40FF — Harlow & Fox
40DD 36F 38E — — Harlow & Fox
40E 36FF 38F — — Harlow & Fox
40F 36G 38FF — — Harlow & Fox
40FF 36GG 38G — — Harlow & Fox
Source: Harlow & Fox sister size chart · read 1 Oct 2026

When your size is past the end of a chart

These charts thin out as the band grows. The biggest cup the two US charts print on a 44 or 46 band is a DDD, and on a 48 band a DD; Harlow & Fox’s chart ends at a 40 band. If your size is not on any of them, take the step yourself:

  1. Write your size in one letter system. Use the letters on the tag, and do not mix a US DDD with a UK E halfway through.
  2. Move the band by two and the cup by one letter the other way, in the cup order the brand you are buying from prints on its own size chart.
  3. Check that the result is on that brand’s size menu. A row worked out this way only counts once that brand’s menu lists the size.

Match the fit problem to a column

  • Band digs in, or is tight on the loosest hook: use “One band bigger”. On the Playtex 18 Hour chart, a band that digs in is too small, and the fix is up a band and down a cup, a 34C to a 36B.
  • Band rides up, or is loose on the tightest hook: use “One band smaller”. ThirdLove’s fit list says: “Band riding up: try your sister size down, since a loose band needs a smaller size.” Playtex gives a 34C to a 32D.
  • Wire sits on the breasts: Playtex reads this as a band that is too loose and, if the cup size is accurate, suggests a sister size down.
  • Cups gape or spill but the band is fine: change only the cup; for gaping, Playtex says to tighten the straps first. ThirdLove’s list says to go down a cup (or try a different style) for gaping cups and up a cup (or try full coverage bras) for spilling over.
  • Your size is not made in that style: take the nearest column that is on the menu; treat two bands as a try-on.
  • US size, UK-sized brand: convert first (on Harlow & Fox’s conversion chart, a US DDD is a UK E and a US G a UK F), then read the UK table.
A black lace bra with its hook-and-eye fastening laid on a white bed next to a makeup palette, a brush and a small framed print
Photo: elif tekkaya / Pexels

Where sister sizing stops working

  • One step is ThirdLove’s limit. Its guide says sister sizes “work best when you move just one size up or down, since going further changes the bra’s overall proportions”, and lists the underwire width, strap spacing and center gore placement as what shifts.
  • A big jump can land in a different kind of bra. Harlow & Fox’s example: going “from a 32E into a 38C is going to not only end up with a band that feels different, but it’s also going to be designed for the lighter support of so-called ‘core’ sizes”.
  • A row on a chart is not a size in stock. Check the menu, and read the returns page before ordering two sizes.
  • Some UK brands skip FF. In Harlow & Fox’s words, “a minority of brands do skip FF cup sizing”; Harlow & Fox’s advice is to treat that brand’s G as an FF, so read its G as the FF row in the UK table.

The other measuring and conversion walkthroughs are in size guides.

Where these numbers come from

The table rows are copied from the sister size charts ThirdLove, Playtex 18 Hour (hosted by Target) and Harlow & Fox publish, read on 1 October 2026; ThirdLove’s chart image was transcribed by hand. A dash means none of those charts prints that size in the row.

Frequently asked questions

What is the sister size of a 32DD?

In US letters, 30DDD one band smaller and 34D one band bigger; ThirdLove's sister size chart prints that row as 30DDD (F), 32DD (E), 34D, 36C, 38B and 40A. In UK letters the row on Harlow & Fox's chart is 28F, 30E, 32DD, 34D and 36C, so the size below is called 30E there.

What is the sister size of a 34C?

32D one band smaller and 36B one band bigger, on both ThirdLove's chart and the Target-hosted Playtex 18 Hour chart. Two steps out, ThirdLove's chart lists 30DD and 38A in the same row.

What is a 34DDD bra size equivalent to?

On Harlow & Fox's conversion chart, a UK 34E, since it puts US DDD/F next to UK E (the brand's DD-cup guide says E or F). Its sister sizes on ThirdLove's chart are 32G and 36DD, with 30H and 38D two bands out. On Harlow & Fox's UK chart the 34E row reads 30FF, 32F, 34E, 36DD and 38D.

What is a 38DD bra size equivalent to?

36DDD one band smaller and 40D one band bigger, with 34G and 42C two bands out, all in one row on ThirdLove's chart. The Target-hosted Playtex 18 Hour chart prints the same 36DDD, 38DD, 40D and 42C. On Harlow & Fox's UK chart, 38DD sits between 36E and 40D.

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