Online Bra Size Calculators: The Good, The Bad and The Hilarious

by Estelle Puleston

Update: there is now a part 2 where I test out more bra size calculators! Check it out here.

So, after a lengthy Twitter discussion earlier this evening about Gossard’s bizarre sizing system and online bra size calculators in general, I decided to sit down and pop my measurements in as many of these ‘find your bra size’ style calculators and size-calculating charts as I could possibly find. Yes, this is what I do for fun.

Here are the results – hopefully they’ll help you figure out which online bra calculators you can trust and which are only good for a quick laugh, although remember that no one bra-sizing system will work for everyone. Get fitted by a (knowledgeable!) lingerie boutique assistant or expect to have to do a bit of changing room trial and error yourself if you want the perfect fit in a particular brand.

Note: Everyone’s bra size will vary from brand to brand and even sometimes between different styles from the same brand. I most often wear a 30E and if a calculator tells me I am a 28E or 28F that doesn’t mean it’s necessarily wrong; that brand may just do their sizing slightly differently. However, if a calculator tells me I’m a 32A then yes, that is wrong. Completely wrong.

Bra Sizes That Actually Fit Me: 30E, 30F, 32E (and yes, I know how a bra should fit).

The Good – Right, Or Almost So – 30E

Yes, the only online bra calculator I found that was actually 100% correct is not from a lingerie brand or lingerie retailer at all. It’s from a website that specialises in calculators, and they know their stuff! Brands and retailers, take note.

Linda’s Online – 28DD or 28E

I like that this calculator gave me two cup sizes to try – not especially helpful if I had no clue what my size was, but it does acknowledge that a woman may be different cup sizes in different brands. Although it’s not exactly my size, and a 28DD definitely wouldn’t fit, a 28F that doesn’t come up small in the band could very possibly fit me and this is pretty close to that size.

Bust’DD – 26F

A 26 band wouldn’t fit me (I find some 30’s too tight) but many people do wear a band size that’s exactly the same as their underbust measurement, especially when you get to larger band sizes. A 26F would be the same size in the cups as a 30DD, which may fit me in a brand whose cup sizing runs large.

Butterfly Collection – 26F, 28E or 24FF

Ths retailer gave me the same basic size as Bust’DD, but I love that it also offered alternative sizes for those who prefer a tighter or looser band. I like mine looser, in which case this calculator tells me to buy a 28E, which again may fit me in a brand whose cups run large.

A Sophisticated Pair – 28DD

Erica from A Sophisticated Pair regularly blogs about good bra fit, so I expected her calculator to be a good one. What I really liked about her calculator was that you could select how tight you like your band to be – I chose the least snug option. The cup size isn’t exactly right but it’s not too far wrong either, and as I mentioned a loose-fitting 28 band would probably fit me too.

The Bad – Well, the ‘Less Good’ (It May Work for Many Women)

Ewa Michalak – 30D (Polish 65D)

Although I haven’t bought from Ewa Michalak, I’ve read a lot of brilliant reviews and this brand is well-known for offering prettier styles in the larger-cup market. So I was expecting their sizing calculator to be pretty decent, and it was certainly unique (I had to enter both tight and loose underbust measurements, and an overbust measurement whilst bent forward) but sadly it’s still 2 or 3 cup sizes out.

The Hilarious – Really, Really Not My Size

Gossard – 32A

This speaks for itself. Thank you to Mariëlle from Petite and Plentiful for pointing out that Gossard are determining your cup size based on the difference between your overbust measurement and your underbust measurement plus four. Even if the +4 method works for you, you should find your cup size based on your actual underbust measurement with nothing added to it. Otherwise, as in this case, you end up with a cup size that’s 4 or 5 letters too soon in the alphabet. (In Gossard’s defence, it does state the calculator is most accurate up to a DD cup – but if I enter an overbust measurement that’s an inch smaller, instead of telling me I am a 30 or 32DD it tells me I am a 30B.)

Ann Summers – 30B

Ann Summers are doing exactly the same as Gossard – they actually ask you to enter your underbust plus 4/5. If I try entering my actual measurements the calculator just doesn’t work.

La Senza – 30C

Again, really not my size. And if I’d opted for a 32-band instead of a 30-band (which their chart tells me will also fit someone with a 26″ underbust) then I don’t even make it to an A cup! – 30C

This calculator is pretty unique in that is also asks for your above-bust measurement, which I thought might make it more accurate but, alas, no.

Babycenter – 30C

Most of the visitors to the Babycenter website will be pregnant, when having a comfortable and well-fitting bra is absolutely crucial, or new mums whose bra size has changed post-pregnancy. So it’s extra shocking that their bra sizing calculator is so wildly off. This one seems to use exactly the same sizing method as

Figleaves – 30C

Yet another website has put me at a 30C, and a major UK retailer this time. I’m almost starting to believe I might just be a 30C… just kidding.

John Lewis – 30B

Shame on you John Lewis! You’ve sold a bra to probably half of the female UK population at some point, and your sizing method is totally wrong. Again, it looks like it’s a case of ‘plus four’ and then finding the cup size based on that altered measurement.

Debenhams – 30B

I could say exactly the same thing for Debenhams as for John Lewis – it’s a major national retailer with the ability to dramatically change how many women are wearing the right size bra, yet is giving out fit advice that’s completely wrong.

So, is it just me these calculators don’t work for? I really doubt it, but I would love to hear your experiences with online bra size calculators and which ones work or don’t work for you!


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Anonymous August 14, 2012 - 5:27 pm

I have had completely different results, to what you have had. last year I was a 32DD and through the stress of my course at university I have reduced to a 32B in some cases a 32C. As a Fashion design student I pride my self in being able to correctly measure my body (not just for bras but for general construction on clothing) and I found with I came out as a 32G. which is something that i am certainly not. I also got the same results from linda. and then with Bust DD i was recommended as being a 28G.
ewa-michalak was the first brand that i came across going down the list that came out as could be correct with a 70C which I believe is a 32C. As someone who is small busted I thought that perhaps the good and the bad is reversed; but then Fig leaves came up as a 32D.
Which leaves me to the conclusion that it is still best to go into the changing rooms armed with a selection of different sizes

Jan Parker September 18, 2020 - 5:01 pm

So, as a fashion design student, I’m wondering if you have a theory as to why there is such a difference in bra calculators? I used a bra calculator and chatted with a “fit expert” and still the reccommended bra cup size was way to big – thought the band fit fine. My personal opinion is that there ought to be breast catagories considered too. Like “happy and perky” or “old and flabby” etc.
Before there were bra calculators I got a better fit because – as you say, going into a changing room is the best way. Unless there is no store close ( within 200 miles) that carries anything near to as big as you need. All of my daughters’ bustlines are huge and even plus-size shops rarely carry bras big enough. Even shopping online gets tiring – I don’t know how you young girls do it!

Estelle Puleston September 18, 2020 - 6:06 pm

Jumping in here to say that personally I believe the wildly varying results from bra calculators is due to there not being one accepted-by-everyone way to measure a bra size.

Some of this is historical – when bras first came about they didn’t have stretch, so as elastic started to be added the bands could theoretically get shorter, but not all brands updated their sizing to reflect this. You’ll find that some brands’ 32 band bra measures 28″ or 30″ unstretched but will stretch up to 32″, while other brands’ 32 brand bra measures 32″ unstretched.

Then added onto that are various other confusing things, such as the fact that cup sizes go up in 1″ increments in countries that use inches but usually 2cm increments in countries that use centimetres (and 1″ and 2cm are not the same thing).

Or, as you touched on, the fact that breast *type* can affect your cup size even if your measurements are the same as someone else with a different breast shape (for example, sagging breasts will stick out forwards less – hence the underbust and overbust measurements will be closer, indicating a smaller cup size – but could still have exactly the same volume as someone with perkier breasts that do project lots and hence gets recommended a larger cup size).

I wrote this post seven years ago when I thought all of these brands were just doing it wrong, but I know better now. SOME of them were definitely calculating things incorrectly, but the truth is that no one bra size calculator will ever be 100% accurate for everyone!

Anonymous August 14, 2012 - 5:27 pm

The Butterfly Collection and A Sophisticated Pair were the closest for me…but still suggesting cup sizes much too large.
There’s no ‘perfect’ calculator as every brand fits so different, each body is different and people have preferences. Fitting is more of an art than a science.

Anonymous August 14, 2012 - 5:28 pm

Thank you for including our calculator! I have some expansion plans for the future which include taking into account current sizing and fit problems too. I think this will help with some of the less accurate results it produces. Of course, calculator only provide starting point sizes, and with so much inconsistency across brands and styles, women still will have a trial-and-error process ahead of them unfortunately.

Anonymous August 14, 2012 - 5:28 pm

Also had problems with… it put me in a 40DD/E UK. I generally wear a well fitting 36E or DD UK depending on brand.

Laura August 14, 2012 - 5:28 pm

Hi Estelle,
I’m a small-cup-sized friend and I think there’s no correct existing calculator (yet). Linda’s Online is the only one to get my size right (and I’m a 32B). I agree with you on the ‘hilarious’ category though! Don’t know how they came up with those charts! According to most of them my size doesn’t even exist.
x Laura from Kukka

Anonymous August 14, 2012 - 5:29 pm

Only Bust’DD gave me my correct size. Butterfly collection gave me the correct band size, but one cup too big. Figleaves gave me a 34GG, which I have a bra in that size, but it doesn’t fit at all! Most of the charts and calculators couldn’t give me a size even when I was adding 4 inches! I have a 13″ difference, and I guess they believe that doesn’t exist!

Anonymous August 14, 2012 - 5:29 pm

The gives me 36G as a result, I wear 32G. I think that’s hilariously bad.

Anonymous August 14, 2012 - 5:30 pm

The calculator at doesn’t give accurate results! I put in my measurements: bust size 36, frame size 29, here is my result:

For UK: Size: 34 inches Cup: G

No. Just… no.

30E/F thank you very much.

Anonymous August 14, 2012 - 5:30 pm

I found that your favorite calculator was not right for me in anything outside of Fantasie. Although if it had worked, it could easily be a favorite because it offered all the options for US/Uk/EU and more. It had me in a 30H and I am a 26H. For me, the best ones were Butterfly Collection, and A Sophisticated Pair which sized me accurately. Gossard tried to get me as a 30G… So it was surprisingly close to the result.
Ewa Michalak (the only company currently offering my size I should point out) has a TERRIBLE calculator. Just awful. It doesn’t even relate to their OWN bras. However, in my experience with the company, the bras run firm but true to UK equivalent sizes. So if you’d like to purchase a non-returnable custom 26 band bra from them… using the butterfly collection or sophisticate pair calculators to choose your size is your best bet.

Anonymous August 14, 2012 - 5:31 pm

I have to say, the Debenhams one surprised me! I was measured wrongly with the +4 method by Marks & Spencer, so when finding this out went to Debenhams and was fitted correctly! Went from a 32G to a 28H. They said that a lot of people had this problem. Moral: Don’t go to M&S!

Nice one for doing this though! It shows how unreliable retailers can be if they do not specialise in larger bust measurements.

Anonymous August 14, 2012 - 5:31 pm switches up the us & uk sizes. It gives me 36FF us and 36H uk. I’m sure this is reversed. Also, my best size is really 32G, so I’m pretty sure they get the difference of the two measurements, calculate cup size, THEN add +4-5 for the band.

Estelle August 14, 2012 - 5:33 pm

I had wondered what these calculators would say for someone with a smaller bust! If you consider they’re adding 4 or 5 to the underbust measurement and THEN calculating the difference with the overbust, what happens if you’re an A, B or C cup? You’d be in minus cup sizes! And I’m pretty sure I’ve never seen a 32minusB for sale anywhere 😉

Estelle August 14, 2012 - 5:33 pm

Ah, what a shame! I thought for a moment I’d found one online calculator that actually worked in but apparently it was just a fluke if it is so, so wrong for you. When done well, bra size calculators can be a really good, useful starting point for someone who has absolutely no clue as to what size they are, but to get the most accurate size possible they would have to take into account all sorts of things more than just measurements – breast shape for example.

Estelle August 14, 2012 - 5:33 pm

Definitely true, but I’m pretty sure the calculators that fall in the ‘hilarious’ category are so incredibly wrong they’re not going to work for anyone. Shall find a small-cup-sized friend to test the theory though! It’s funny The Butterfly Collection and A Sophisticated Pair both gave you too-large cup sizes, for me they were both a tad too small. Tempted to buy something I can return in a 28E though just to try it out. Estelle x

Estelle August 14, 2012 - 5:34 pm

Thank you for your comments everyone!
Although I set out to determine which calculators are right and which aren’t, I think I’ve proved something I kind of already knew anyway – no one calculator will work for everyone.
I’d be interested to hear from anyone else who typically wears a 30E/F to see if they get the same results as me!

Estelle August 14, 2012 - 5:34 pm

Ah what a shame! A 40DD would be equivalent in the cups to a 36F so only one or two cup sizes out (not as bad as some of the calculators further down the list!) but still not great when one cup size difference can totally change the fit of a bra :/

Estelle August 14, 2012 - 5:35 pm

I guess it depends on how tight/loose you like your band. I also wear a 30E/F but my measurements are totally different (26″ underbust, 32″ overbust). I like my band loose-ish so plus four works for me, which someone else pointed out was what this calculator is using.

I guess no perfect calculator exists :/ Not that it could really – fit has to take into account so many different factors, not just measurements.

amy lambert April 15, 2016 - 10:02 am

Hi there,
I am 34 B and i am still using the conventional way to get perfect bra(yup by trying it on). It is simply because I haven’t found the matched online calculator.

Estelle April 15, 2017 - 8:26 am

Trying a bra on is always the best (only, actually) way to tell if a bra’s going to fit. But it would be nice for a bra fit calculator to always give you a rough idea of your size, especially for those who just don’t have a clue.

That’s probably one of the biggest problems facing online lingerie boutiques – customers can’t see if it fits quite right so they’ll be put off buying or end up returning items. A bra calculator tool is kind of like an online fitting room, but no one’s perfected it yet it seems!

Lea June 3, 2017 - 4:50 pm

None of them. I have been searching for years for a bra that doesn’t hurt me, and supports me. The idea that a woman should wear a bra that literally cuts her skin, or rubs her raw, is absolutely ludicrous! I would rather sag! I have been large busted my entire life. At age 11, my very first bra was a 28D. I’m 6ft tall and Hella curvy. Especially after 3 children, age, and weight gain. I measure 37″ underbust, and 47.5″ chest measurement. I have a lot of side boob, which I believe is part of the fit issue. Earlier this year, I was fitted by photo and measurement online. They recommended a 36HH in the Panache brand Tango II. At first it felt like it fit way better than any other bra I’ve ever had. 6 hours into wear, I had severe raw marks, and band rolling on the right side. I consulted panache directly through their Facebook page. Wires aren’t wide enough to encase my girls, band may also be wrong. I give up!!! I refuse to be injured by an $80 bra!!!!!!!!! Now I’m told by these calculators to try everything from a 42GG, 38J, 40H, 40G, 36I, etc.etc. I’m seriously considering buying large Ace bandages and wrapping up the goods!

Estelle Puleston June 3, 2017 - 5:43 pm

Sorry to hear you’re having so much trouble to find a comfy bra 🙁 If you have a bra that fits well and it’s just the rubbing that’s the issue, you may want to look into either underwire cushions (e.g. or bra liners (e.g. that essentially form a soft cushion between the bra and you to reduce chafing.

It may also be worth looking into bralettes. They WON’T provide as much support, for definite, so that may rule them out for you. But if you’re more bothered about comfort than lift, you may like them. Here are some reviews: If they look too unsupportive for you, there are also structured, wire-free bras that are somewhere between a wired one and a bralette.

And one last tip – you might want to give new brand Trusst a go. Their bras have a plastic structure inside to support the bust from below, for people who don’t get on well with wires. There are a couple of blogger reviews of the brand if you Google for them 🙂

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ariawhatever March 15, 2030 - 4:22 am

Some are successful and others are just awful! With a ribcage of 28″ and a 35″ bust, it should be a UK 28F, US DDDD/G. I am stil wearing bras too large in the back and cups too small because my only choice is online. Generally speaking, a 28F is a small medium size. If you saw me, you would say B or C probably but they are not. They also aren’t huge like most teenage girls and adult women think they are. On a slender, 5’8″ frame roughly, they look smaller than they would be on a shorter person.

Estelle March 15, 2030 - 7:12 pm

I know what you mean, I used to think of myself as full-busted but after losing a bunch of weight I’m now a 30E (some bra fit evangelists would put me at a 28F but I like looser bands) and I don’t think of my bust as being ‘full’ at all now. It’s distinctly average sized! And I’m short 🙂