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“A style-led approach to fuller-bust swimwear. Flawless fit meets modern sophistication.” British Vogue, June 2026
Fully adjustable low rise tie side bikini bottoms which can be adjusted for the perfect fit.
• Adjustable tie sides for desired fit
• Fully lined for shape retention and modesty
• Luxurious Quality – Made with premium Italian eco-friendly swim fabrics with superior shape retention, UV protection, and resistance to chlorine and swim lotions.
• Exclusivity – Each Core Swim piece is part of a small, limited-edition collection, ethically and sustainably made in the EU. Never mass produced.
The key to your bikini doing what it has been designed to do is the fit. If it doesn't fit you properly, it won't support you properly.
The Core Bikini Top:
1. Back size:
The Core bikini top has been designed to be as close as possible to your bra size so you should order your standard back bra size (e.g. 36). Please note that the Core bikini has been designed to fit snuggly on your back size. We do not mean tight (that would be uncomfortable) but we do mean snug. The reason for this is:
1. A lot of the support from the bikini (and your every day bra) comes from the back. If the back is too big, you will lose support
2. Although the Core Swim bikini is fully lined (including the wings) to minimise stretch and maximise support when wet, we want you to be just as confident in your wet bikini as your dry bikini so we've designed it snug (again not tight!) so there is no need for those public adjustments when you get out of the pool.
Advice: If your bikini arrives and the back is not snug, consider a smaller size as you may get a better support. If it is too tight, please consider the next size up.
Note that if you size your back size up or down, you will also need to change your cup size to reflect this (it's called "sister sizing", see below).
2. Bikini cup size:
This is a sister sizing bra size chart and shows you the size you need to adjust to depending on the individual fit issue. For example, if you had a 36FF and the back was too tight but the cup fit, you would go up a back size and down a cup size to a 38F. Or, if the 36FF was too big on the back but fine in the cup, you would go down a back size and up a cup size to a 34G (see black arrows):

If the back fit you perfectly but the cup feels big then just go down a cup size to a 36F. Or, if the cup is not covering you as much as you would like or there is bulging, then go up a cup size to a 36G (see the red arrows).
International Size Conversions:


All orders are shipped from the UK and may be subject to customs fees, import duties, and taxes once the shipment reaches your country. These charges are set and collected by your local customs authority and are outside of our control. Customers are responsible for paying any additional fees that may apply.
If you would like more information before placing an order, we recommend contacting your local customs office.
Amazing fit. Beautifully designed. Incredible customer care.
Highly recommend
The shape is amazing and I feel completely secure. I always buy bra sized bikinis but I can honestly say this is second to none I’ve tried before.
Gorgeous bikinis, perfect fit and quality fabric and manufacture. Delighted and so recommended. x
Love the design, quality (support is fantastic and bikinis retain shape and colour through washing). Service is ace too - prompt delivery.
Love these high waisted bottoms. I feel covered and they’ve got a power lining in the tummy if you want some support
Fits perfectly! Makes me feel secure and feminine without showing too much