Bikini Fit by Bust Size: Big Bust, Small Bust & Between

Most bikini sizing advice assumes your top and bottom are the same size. For a lot of women they are not, and the gap is usually at the bust. This guide is about choosing by what your bust actually needs — more support, or less bulk — and it starts from the thing that makes it easy: on every PEAKSOUL set the top size and the bottom size are chosen separately, at the same price as a matched set.

Start here: the top is sized on your underbust, not your hip

The single most common sizing mistake is picking one letter for the whole set because that is what the shop expects. Size the top on your underbust and the bottom on your hip, and treat them as two independent decisions. There is a fuller explanation in our guide to buying a bikini in two different sizes.

If your two sizes are more than one step apart, every design is also sold as an individual top and an individual bottom in Mix & Match, so you are never forced to compromise on one half.

If you have a fuller bust

Two things matter more than the rest: where the support comes from, and how much the band can be adjusted.

Support comes from the band, not the cup

A bikini top holds by tension across the back and under the bust. That is why a top that feels loose under the bust will not be fixed by a bigger cup — it needs a firmer band. Between two sizes on the top, the smaller usually holds better for this reason, because the band is doing the work.

Underwire, if you want structure

Three tops in the range are built with underwire: the Pearl Shiny Blue Marine top, the Pearl Shiny Black top and the Shiny Olive Green top. Underwire gives a defined shape and keeps the bust separated rather than compressed, which is usually what people mean when they say a top "holds".

Halter, if you want the weight off your back

A halter neck moves part of the load onto the neck and shoulders instead of the band alone. The Cancun fuchsia top is the halter in the range, and it also has removable cups so you can set the amount of padding yourself.

If your bust and waist are different sizes

This is exactly the case independent sizing exists for. A larger top with a smaller bottom is a normal order here, not a special request, and it costs the same as a matched set. Buy the top on your underbust and the bottom on your hip and stop averaging the two.

If you have a smaller bust

Removable cups let you decide

Most tops in the range — 42 of them — have removable cups. That is the useful feature here, because it works in both directions: leave them in for shape, take them out for a flatter, softer line. You are not locked into the decision the way you are with a fixed moulded cup.

Triangle tops are the largest group in the range and the most adjustable, because the ties let you set both the width and the height of the cup. Good starting points are the Royal blue top, the Citrus yellow top, the Peach top and the Pearl Shiny nude top.

If you are smaller on top and fuller on the hip

The mirror image of the case above, and it has the same answer. Take the smaller top and the larger bottom. Because the two halves are selected independently, this is a single normal order — and if the gap is wide, buy them as separates from Mix & Match.

What to do when you are between two sizes

• On the top, the smaller size usually holds better. Support comes from the band, and a band that is slightly firmer is doing its job.
• On the bottom, the larger size is usually more comfortable over a long day, because swim fabric relaxes once it is wet.
• Do not average the two. Averaging is how you end up with a top that rides up and a bottom that digs in at the same time.

If something already fits badly, our guide to bikini fit problems and how to fix them works through the specific symptoms.

A note on shape, not just size

Every piece in the range is cut in the same 90% polyamide, 10% elastane fabric, which holds its shape wet and dry. Style changes how a top sits as much as size does — a triangle sits differently from an underwire top at the identical measurement. Our guide to bikini styles explained covers each cut in the range and what it suits.

Frequently asked questions

Which bikini top is best for a bigger bust?

One with real band support, and ideally underwire or a halter neck. In this range that means the Pearl Shiny Blue Marine, Pearl Shiny Black or Shiny Olive Green tops for underwire, or the Cancun fuchsia top for a halter. The band is what holds, so do not size up hoping a larger cup will fix a loose band.

Can I buy a bikini top and bottom in different sizes?

Yes. Every set has independent top and bottom size selectors at the same price as a matched set, and every design is also sold as an individual top and bottom if your sizes are more than one step apart.

What is the best bikini for a small bust?

A top with removable cups, so you control the padding, and a triangle style, because the ties let you adjust both width and height. 42 tops in the range have removable cups.

I am a bigger bust with a small waist — what do I order?

A larger top with a smaller bottom. That is a standard order here rather than a special case, and it is priced the same as a matched set.

Should I size up or down if I am between sizes?

Down on the top, up on the bottom. Support on the top comes from the band, and swim fabric relaxes on the bottom once it is wet.

Do the tops have padding?

42 of the tops have removable cups, so padding is your choice rather than fixed. Take them out for a softer line, leave them in for shape.

Where to start

Browse every top and bottom individually in Mix & Match: Tops & Bottoms, or start from a category: bikini, reversible crochet, party and night, or skin tones and neutrals.