Waist measurement - measure around the narrowest part of your waist

Hip measurement - measure around the fullest part of your hips

When to size up or size down?

If your waist and hip measurements place you in two different size categories, there are a few ways to determine which size to go with. Consider your level of activity - if you plan on being very active and engage in water sports, size down for a tight fit. For a more relaxed experience, you may choose to size up for a looser fit. For most bikini bottom styles the hip measurement is more important than the waist measurement in finding the right fit.

If your weight fluctuates, choosing adjustable pieces will allow you to customize the size/fit as needed.

All tops have adjustable bands/straps, so same bikini top can fit multiple sizes.

When selecting a bikini top size, focus on choosing based on preferred front coverage and support in the cup size rather than the band size

When choosing a one-piece swimsuit, consider both your bottom size and top size, and prioritize the bottom size, because the top part of the suit is adjustable. However if your bottom and top sizes are significantly different, or if your torso is longer or shorter than average, it is best to opt for a customized suit, and provide your measurements for bust, underbust, waist, hip and torso.