Your guide to finding the perfect Śiirap fit

Finding swimwear that actually fits a fuller bust can feel impossible, especially when cup sizes seem to change depending on the style, brand, or how supportive the garment is.

That’s where sister sizing comes in.

At Śiirap, we design swimwear specifically for D+ busts, so understanding your sister size can help you achieve the perfect balance of support, comfort, and shape.

What Is Sister Sizing?

Śiirap bikini tops use a unique 1–6 sizing system designed specifically for fuller busts.

Instead of traditional cup sizing alone, each Śiirap size is built around sister sizing, meaning multiple bra sizes can comfortably fit within the same swim size.

This allows for:

• More flexibility across cup and band sizes
• A better fit through stretch swim fabric
• More personalised support and shaping
• Easier sizing between styles

For example, a Śiirap Size 3 fits:

• 8G
• 10F
• 12E
• 14DD
• 16D

These are considered sister sizes because although the band size changes, the overall cup volume remains similar.

Why Sister Sizing Matters In Swimwear

Swimwear fits differently to lingerie.

Because swim fabric stretches, some customers prefer:

• A firmer band for extra support
• A slightly looser band for comfort
• More coverage through the cup
• A more lifted or cleavage-focused fit

Knowing your sister size allows you to customise your fit preference without compromising support.

At Śiirap, our pieces are designed to sculpt, support, and hold fuller busts properly, but your ideal fit may still vary depending on how you like your swimwear to feel.

Understanding The Śiirap Size System

Śiirap bikini tops use a unique 1–6 sizing system designed specifically for fuller busts.

Our sizing works using sister sizing, meaning multiple traditional bra sizes can fit within the same Śiirap size. This allows for a more flexible fit across cup and band sizes while still maintaining support, shape, and comfort.

As a growing independent brand, we created this system as a way to make supportive D+ swimwear more accessible from the very beginning.

Developing individual cup-sized swimwear across every size range immediately was not realistic for a small business, so we designed a fit system that allows flexibility while still delivering the support and structure fuller bust customers actually need.

As Śiirap continues to grow, expanding into more individual cup sizing is something we would love to introduce in the future.

Śiirap Bikini Top Size Guide

Because all Śiirap bikini tops feature a 6-loop adjustable back closure and fully adjustable straps or halter neck ties, some customers may comfortably wear more than one size depending on their preferred fit.

How To Use Sister Sizing At Śiirap

Because our sizing groups together sister sizes, you may fit more than one Śiirap size depending on:

• How supportive you like your swimwear
• Your preferred level of cleavage or coverage
• Your underbust measurement
• The style you are shopping

For example:

• If you usually wear a 12DD, you would typically wear a Śiirap Size 2
• If you prefer a firmer fit, you may prefer sizing down depending on your underbust measurement
• If you are between band sizes, your sister size may fit better in certain styles

All Śiirap bikini tops are designed with a 6-loop adjustable back closure and fully adjustable straps or halter neck ties, allowing you to customise your fit for the perfect balance of support, lift, and comfort.

Our adjustable construction is designed to give flexibility while still keeping you secure.

Why Śiirap Uses Sister Sizing

Śiirap created this sizing system as a growing independent brand wanting to make supportive D+ swimwear more accessible from the very beginning.

As a small upcoming business, developing individual cup-sized swimwear across every size range immediately was not realistic, so we created a sister sizing system that allowed us to offer flexibility, support, and a better fit experience while still maintaining the quality and construction our pieces are known for.

Traditional swim sizing often fails fuller busts because it assumes cup size alone determines fit.

At Śiirap, we know support comes from the balance between:

• Band tension
• Cup volume
• Fabric support
• Strap positioning
• Underwire structure

Using sister sizing allows us to create swimwear that feels more flexible, wearable, and supportive across multiple bust sizes, without compromising on shape or style.

Śiirap Fit Notes

Every Śiirap piece is designed with D+ support in mind, but different styles may fit differently depending on:

• Underwire structure
• Strap placement
• Coverage level
• Fabric tension
• Desired fit preference

Some customers prefer sizing down for a sculpted fit, while others prefer a softer, more relaxed feel.

If you are between sizes, sister sizing can help you find your perfect fit.

Need Help Finding Your Size?

We know D+ swim shopping has never been straightforward, that’s exactly why Śiirap exists.

If you need help choosing your size, contact our team and we’ll help guide you to the best fit for your bust, shape, and preferred level of support.

Because supportive swimwear should actually fit. And still look hot.