Most people do not wear the same size on the top and the bottom, which is the practical reason to buy swimwear as separates rather than as a set. Rat & Boa sells its bikini tops and bottoms individually, with tops around $95 to $100 and bottoms around $85 to $105, so a pair lands close to $200. That structure also means you are not stuck with a matching set that only works as one outfit. Two tops and two bottoms give you four combinations for the cost of two sets, and it lets you replace the piece that wears out first without buying the other half again. Elastic and lining go before the fabric does, and it is usually the bottoms.

Mixing works when something intentional connects the two pieces. The simplest version is a shared colour, so a print that contains an orange pulled next to a plain orange bottom reads as a choice. The second approach is matching the intensity, keeping a bold print with another bold print of a different scale rather than pairing it with something washed out. The third is tone, where a metallic piece like the Petra bottom at $95 sits with a plain dark top because both feel polished. What tends to fail is two mid saturation prints in unrelated colour families, which looks like the pieces arrived separately. Keeping one half plain is the safest way to buy a print you already like.

Buying swim separately takes longer and it is worth it, mostly because the fit stops being a compromise. We would start with one plain bottom in a colour you already wear, then let the tops be where the print and the shape change. That order gives you the most combinations for the least money, and the plain piece is the one you will still be reaching for at the end of the summer. If you take one thing away, buy the bottom first and buy it plain. All prices listed here were live and in stock when this edit was built, and tops and bottoms are sold as individual items, so check both before you assume a pair is complete.