Looking for the M&S bra size chart or calculator? Start with the official M&S size guides for the country and product you are shopping. For a separate measurement-based estimate, use our bra size calculator, choose inches or centimetres, and select your sizing region. Check the result by trying on the bra.
This is an independent guide from Bra Size Calculator. We are not affiliated with or endorsed by Marks & Spencer. Our calculator is not the official M&S fitting service.
Which M&S bra size chart should you use?
Use the size guide attached to the exact bra on your local M&S website. A UK bra label, an international label conversion, and a body-measurement chart answer different questions. A band number is a size label; it is not always the same number as your underbust measurement.
For UK shopping, open M&S UK size guides and select the relevant lingerie category, or use the product page’s size guide. Check bralette and dual-size styles against their own charts.
M&S measurement chart example: India
The following band-selection ranges are from the inch table on M&S India’s official bra size guide. This is a regional example, not a universal M&S UK fitting rule. The centimetre column below converts those inch ranges using 1 inch = 2.54 cm, rounded to one decimal place.
| Band label in M&S India chart | Underbust in inches | Underbust in cm (converted) |
|---|---|---|
| 28 | 23–24 | 58.4–61.0 |
| 30 | 25–26 | 63.5–66.0 |
| 32 | 27–28 | 68.6–71.1 |
| 34 | 29–30 | 73.7–76.2 |
| 36 | 31–32 | 78.7–81.3 |
| 38 | 33–34 | 83.8–86.4 |
| 40 | 35–36 | 88.9–91.4 |
| 42 | 37–38 | 94.0–96.5 |
| 44 | 39–40 | 99.1–101.6 |
This table selects a band label only. Use the same regional guide’s overbust columns to find a cup label; do not combine its band result with a different calculator’s cup formula. If you fall between published ranges, compare nearby sizes with fit checks or ask a fitter.
How to measure in inches or centimetres
Use a flexible measuring tape and record the unit with both numbers. Avoid thick padding or bulky clothing. Keep the tape level around your back and repeat the measurements if the tape has shifted.
Underbust: Measure around the ribcage immediately beneath your breasts. Keep the tape snug without digging in. Write down the measurement before rounding it or turning it into a band label.
Bust: Measure around the fullest part of your bust without flattening the breast tissue. Keep the tape level and breathe normally.
Use one complete method: Enter both measurements in the same unit into our calculator, or follow the matching band and cup instructions in your retailer’s chart. For more measurement context, try the six-measurement calculator. Each result is a starting estimate, not a guarantee of fit.
Why can an M&S chart and another calculator disagree?
Charts can use different band-selection conventions and cup progressions. For example, the M&S India chart above maps a 31–32 inch underbust to a 36 band. That observation does not establish how every M&S country site, product, or in-store fitting works.
M&S’s current UK measuring guidance emphasises assessing how a bra fits and treats tape measurements as a rough starting point. Do not automatically add or subtract four inches from every recommendation. Compare the method, regional labels, and actual fit first.
Check the fit before choosing a size
Use these checks when trying on an M&S bra. They summarise the retailer’s UK fit guidance:
Band: It should remain level and comfortably secure. A band that climbs your back may be too loose. Cups: Look for smooth coverage without spilling or persistent gaping. Wires: They should not press on breast tissue or poke. Straps: Adjust them so they stay in place without digging in.
Change one fit variable at a time. If the band feels right but the cups spill, compare a larger cup in the same band. If a different style solves the issue, you may not need to change your usual size. M&S notes that cut, style, and fabric affect fit in its size-guide guidance.
When should you try a sister size?
Sister sizes change the band while keeping a similar cup volume. In M&S’s UK example, 34C, 32D, and 36B are sister sizes. If a 34C’s cups fit but its band is loose, a 32D is a size to compare; if the band is tight, compare 36B. These are alternatives to try, not guaranteed replacements.
If both band and cups fit poorly, moving to a sister size alone may not solve the problem. See our guide to bra size charts and sister sizes for more examples.
Getting help with an M&S fitting
For current options, visit M&S’s official Bra Fit service page. Bring your usual size and explain which part of your current bra feels uncomfortable. Ask to compare the recommended size in more than one style.
Before ordering several sizes online, check the current returns conditions for the exact items. You do not need to buy two bras simply because two sizes look plausible.
Frequently asked questions
Is this an official M&S bra size calculator?
No. This page is independent. Our calculator provides a general starting estimate; M&S’s own guides and fitting services are linked above.
Can I use centimetres?
Yes. Choose cm in our calculator and enter both measurements in centimetres. When converting by hand, divide centimetres by 2.54 to get inches. Converting a measurement does not convert a bra size label.
Does M&S always add four inches?
Do not assume one rule applies everywhere. The regional table above uses a different band convention from some calculators. Follow the guide for your product and country, then assess the fit.
Are M&S cups the same in every country?
Check the local product label and conversion guide. Avoid assuming that a cup letter is interchangeable across regional sizing systems, particularly beyond D.
Should I size down in every M&S bra?
No. Identify whether the band, cup, or style is causing the problem before choosing another size. A smaller band can make an already-tight bra less comfortable.
Sources and editorial note
Sources checked on 5 September 2026: M&S UK size guides; M&S India bra size guide; M&S UK measuring and fit guidance; and M&S Bra Fit services. This revision removes unsupported client anecdotes and blanket claims about M&S sizing. No professional fitting or clinical review is claimed.