How to Measure Bra Size (UK) – Measurements, Bra Size Chart

Measuring your bra size is the first step to finding a bra that actually fits. This guide shows you exactly how to measure, what those measurements mean, and how to use a UK bra size chart as a reference. Once you have your numbers, you can use a calculator to get a reliable starting size, then fine-tune fit if needed.

What You Need Before Measuring

You don’t need anything fancy — just the basics:

• A soft measuring tape (tailor tape works best)
• A mirror (to check the tape stays level)
• A non-padded bra (recommended for the bust measurement)
• Optional: notes app or pen

If you don’t have a non-padded bra, that’s okay — just avoid anything heavily padded or push-up, because it can inflate your bust measurement.

Step-by-Step: How to Measure Your Bra Size

Step 1: Measure Your Band (Underbust)

This measurement helps determine your band size (the number part, like 32, 34, 36).

1. Stand straight and relax your shoulders.
2. Wrap the tape snugly around your ribcage, directly under your bust.
3. Keep the tape parallel to the floor all the way around.
4. Breathe out normally (don’t hold your breath).
5. Write down the number in inches or cm.

Band measuring tips (quick):

• Snug means firm but not painful
• Don’t measure over clothing
• If the tape slips down your back, it’s probably too loose

Step 2: Measure Your Bust (Fullest Part)

This measurement helps determine your cup size (the letter part, like C, D, DD).

1. Wear a non-padded bra if possible.
2. Wrap the tape around the fullest part of your bust (usually across the nipples).
3. The tape should be comfortably placed, not digging in.
4. Keep it level across your back.
5. Write down the number in the same unit as your band measurement.

Bust measuring tips (quick):

• Don’t pull the tape tight — that can underestimate your bust
• Don’t measure over padded bras — that can overestimate
• Check in the mirror that the tape is level

Should You Measure in Inches or CM?

Either is fine. The UK uses both, and what matters most is consistency.

• If you measure your band in inches, measure bust in inches
• If you measure in cm, keep both in cm

Your results won’t be “more accurate” just because you used inches or cm — accuracy comes from tape placement and tension, not the unit.

What Do Bra Size Measurements Mean?

Your bra size has two parts:

• Band size (number) = based mainly on your underbust
• Cup size (letter) = based on the difference between bust and underbust

Important: Cup size is relative to band size.

That means a “D cup” isn’t one fixed volume — it changes depending on the band. This is why two people can both wear a “D cup” and look completely different.

That’s also why calculators are helpful: they turn raw measurements into a usable starting size, and then you can adjust for comfort and brand differences.

UK Bra Size Chart (Reference Only)

Use the charts below as a quick reference, not a replacement for a calculator. Real bodies, bras, and brands vary — so treat this as a starting guide.

UK Band Size Chart (Underbust → Band Size)

This chart gives a typical UK band size range based on underbust measurement.

Reference only: band sizing can vary slightly by brand and bra style.

Underbust (in)	Underbust (cm)	Suggested UK Band Size
26–27	66–69	28
28–29	71–74	30
30–31	76–79	32
32–33	81–84	34
34–35	86–89	36
36–37	91–94	38
38–39	97–99	40
40–41	102–104	42
42–43	107–109	44
44–45	112–114	46
46–47	117–119	48

UK Cup Size Chart (Bust − Underbust Difference → Cup Letter)

Cup letters typically follow the bust–underbust difference. UK brands commonly include DD, FF, GG, HH, JJ etc.

Reference only: cup lettering can vary by brand. Use this as a guide.

Difference (in)	Difference (cm)	UK Cup
1	2.5	A
2	5	B
3	7.5	C
4	10	D
5	12.5	DD
6	15	E
7	17.5	F
8	20	FF
9	22.5	G
10	25	GG
11	27.5	H
12	30	HH
13	32.5	J
14	35	JJ
15	37.5	K

Common Measuring Mistakes That Cause Wrong Sizes

These are the biggest reasons people get a surprising result:

• Tape isn’t level (especially at the back)
• Band measured too loose (leads to bands that ride up)
• Bust tape pulled too tight (leads to cups that feel small)
• Measuring over padding
• Relying on a chart alone without checking fit

If your result feels “wrong,” it often isn’t your body — it’s the measurement method. Re-measure once carefully before assuming the calculator is incorrect.

What to Do After Measuring

Once you have your measurements:

1. Calculate your UK starting size using your numbers.
2. When you try bras, check the fit:
   • band feels firm and level
   • cups contain tissue without gaping/spilling
   • straps support but don’t carry the weight
3. If the fit is close but not perfect, use sister sizes to adjust the band while keeping a similar cup volume.