Find a Bikini That Fits
Measure, test the fit, pick the right cut and shop with your numbers.
Here is the step-by-step: take four measurements, test how a top and bottom actually fit, match the cut to what you will be doing, then shop with your numbers in hand. It takes about ten minutes, and it works the same way for plus size swimwear, maternity swimwear and everything in between.
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What to Have Ready
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Get a soft fabric measuring tape (a piece of string and a ruler will also do), a mirror, and a pen or your phone for notes. Stand relaxed with your feet together and breathe normally. Measure over bare skin or a thin, unpadded bra, because padding adds inches that swimwear will not have. Write every number down so you can compare it with each brand's own size chart later, or hand it to an online personal stylist if you prefer help choosing.
How to Measure Yourself
Begin with the underbust. Wrap the tape snugly around your ribcage right below your bust and keep it level at the front and the back. This number guides the band of the top, which does most of the supporting work. Then measure around the fullest part of your bust with the tape level and just touching your skin. Do not pull it tight, or the result will run small.
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For bottoms, find your natural waist, the narrowest part of your torso, usually at the navel or slightly above it. Then measure your hips around the fullest part of your seat. Check the tape in the mirror to be sure it stays parallel to the floor, because a tape that dips at the back gives you a false number and a bottom that does not sit right.
- Underbust: guides the band or overall top size and how firm the base of the top needs to be.
- Bust: tells you how much cup room you need, especially when you compare it with your underbust.
- Waist: helps you decide where the bottom should sit and how snug the waistband should feel.
- Hips: is usually the deciding number for bottoms, because it drives coverage and comfort at the leg openings.
Brands do not size the same way, so treat your numbers as a starting point rather than a fixed size. Compare them with the size chart on every product page. If you fall between two sizes, read the fit notes or reviews for comments about running small or large, and consider whether the style has adjustable ties. An online personal stylist can also do this comparison for you if you would rather skip the charts.
How to Tell Whether a Top Fits
Start with the base of the top. The band or underside should lie flat against your ribs without digging in or leaving deep marks. Slide a finger underneath: it should fit with a little resistance. If the band rides up toward your armpits when you raise your arms, it is too loose, and the straps will end up doing a job they were never designed to do.
Next, look at the cups or fabric panels. Your bust should sit fully inside them, with no spilling over the top or sides and no gaping at the edges. Straps should stay in place without cutting into your shoulders. On tie styles, you should be able to tighten the strings without pulling the fabric out of shape or bunching the center. If straps dig in on every top you try and the strain stays with you all day, that is a conversation some people take to a surgeon about breast reduction surgery.
Finish with a movement test. Lift your arms, lean forward, twist from side to side and do a few small jumps. A good top stays where it is, with only a little shifting. If you keep tugging it back into place in the fitting room or at home, that is a clear sign it will frustrate you at the beach or by the pool.
How to Tell Whether a Bottom Fits
The waistband or side straps should lie flat on your skin without pinching or rolling over. Leg openings should hug without cutting a line into your thighs. If the fabric bulges around the edges, the size is probably too small. If it gaps at the sides or the back, it is probably too large, or the cut does not suit your shape. Higher-cut legs also show more of the bikini line, so think about how you will handle that, whether with a razor, wax or bikini laser hair removal.
Check the back coverage in a mirror, then bend over and sit down. The fabric should stay comfortably in place instead of sliding or bunching. Walk a few steps and squat once. Good bottoms feel almost invisible after a minute. If you keep adjusting them, try a different rise, a different coverage level or a different size. If you are weighing laser treatment for the bikini line, compare laser hair removal cost between a few providers well before your trip.
Which Cuts Suit Which Needs
The right cut depends on how much support and coverage you want and what you will actually be doing. Here is a quick guide to the common options so you can narrow your choices before you start shopping.
- Triangle top: adjustable ties, easy to fine-tune, and a good pick for lounging and for sizes that are hard to match.
- Underwire or molded-cup top: more structure and lift, useful if you want extra support for a fuller bust.
- Bandeau top: minimal straps and a clean line, best for sunbathing rather than lots of movement.
- Sporty or high-neck top: more coverage and a secure feel for swimming, paddling and active days, and a common shape for UPF swimwear.
- Full-coverage bottom: more fabric at the back and a comfortable feel for active use.
- High-waist bottom: sits at or above the navel and adds coverage through the midsection.
- Hipster or tie-side bottom: sits lower, adjusts easily and makes a flexible everyday choice.
- Cheeky bottom: less coverage at the back, a style choice best suited to relaxed beach or pool time.
Picture your most likely day. If you will be swimming laps, playing volleyball or chasing kids, choose a secure top and a bottom with more coverage and a firm waistband. If you will mostly be lying by the pool at one of the all inclusive resorts, you can go with lighter structure and more adjustable ties. Most people end up owning a couple of cuts, and anyone booking beach vacation packages usually packs at least two.
Sizing Tops and Bottoms Separately
A bikini comes in two pieces, and nothing says both have to be the same size. Many people wear a different size on top than on the bottom, and many shops sell each piece on its own. Use your bust and underbust numbers for the top and your waist and hip numbers for the bottom, then pick each piece separately. This matters even more with plus size swimwear and maternity swimwear, where top and bottom needs often differ.
Where to Shop for the Right Size, and Paying with a Cashback Credit Card
A store that focuses on swimwear makes comparing easier. SwimOutlet is built around swimwear, so you can browse many styles and brands in one place and compare cuts side by side. Open the size chart for each item, match it to your measurements, and read the fit comments before you add anything to your cart. At checkout, paying with a cashback credit card returns a small share of what you spend.
Nordstrom is another option if you want to browse swimwear from a range of labels alongside other items. Whichever store you use, look at the product photos for coverage, check how the item is described, and read the return terms before you order. Buying two nearby sizes of a favorite style can be a practical way to find the better fit; if you use buy now pay later or a cashback credit card for that, check the terms and send the extra size back on time.
Test Before You Commit, Then Sort Out Your Travel Insurance
Try your new swimwear at home with the tags still on and wear it for a few minutes while moving around. Check it in the mirror from the front, the side and the back. If possible, test it wet, because some fabrics stretch or feel different once they are damp. Only remove the tags once you are sure. If the suit is for a trip, pack it in your carry-on in case a checked bag goes missing, and compare travel insurance options while you are booking beach vacation packages or all inclusive resorts.
What if my bust and underbust numbers point to different sizes?
Should a bikini top feel tight?
Can I buy a different size for the top and the bottom?
How do I know if a bottom has enough coverage?
A good bikini fit comes down to a few simple steps: measure carefully, test how the top and bottom stay in place when you move, choose cuts that match your plans, and shop with your numbers next to the size chart. Start with SwimOutlet or Nordstrom, compare a few options and choose the pieces that feel comfortable. If a trip is coming up, settle your travel insurance and pack the suit that passed every test.
