How to choose the right bikini and swimsuit size
Choosing the right size for a bikini or swimsuit can seem harder than choosing everyday clothes. The fabric is stretchy, each brand has its own fit, and small cutting details can completely change the fit.
The good news is that, with a few simple measurements and attention to the characteristics of each model, it's possible to buy swimwear online with much more confidence.
In this guide, we explain how to correctly measure your body, how to choose the right top and bottom size, and how to tell if a bikini or swimsuit truly fits well.
At Bikinikloset, many of our bikinis are sold separately, allowing you to choose one size for the top and another for the bottom. This is one of the most effective ways to achieve a truly personalized fit.
Why sizes can vary between brands
The size you usually wear in clothes is a good starting point, but it shouldn't be the only reference.
Swimwear brands may use:
- different size charts;
- fabrics with more or less elasticity;
- more minimal or wider cuts;
- different cups and structures;
- Brazilian, Colombian, or European fits.
Therefore, a size M in one brand may fit similarly to an S or L in another.
Before choosing, always consult the size chart available on the product page. At Bikinikloset, each product features the corresponding brand's size chart next to the size selection.
You can also consult our frequently asked questions about sizes and exchanges.
How to take measurements correctly
To get reliable measurements, use a flexible tape measure and measure directly on your body or with thin underwear.
The tape should be straight and close to the body, but not tight. Measurements should be taken in a natural position, without sucking in your stomach or holding your breath.
The main measurements are the bust, underbust, waist, hip, and, for swimsuits, torso length.
How to measure your bust
Wrap the tape measure around the fullest part of your bust.
The tape should remain horizontal, passing across your back at the same height. Avoid pulling too tight, as this can lead to choosing a cup size or overall size smaller than necessary.
How to measure your underbust
Place the tape directly below your bust.
This measurement is especially important for tops with underwire, a structured band, a clasp, or sizes similar to bras.
A properly fitting top should feel firm around your ribcage, without riding up your back or making it difficult to breathe.
How to measure your waist
Measure your waist at the narrowest natural part of your torso, usually above your belly button.
Do not pull the tape or suck in your stomach. The measurement should represent your body in a comfortable and natural position.
This measurement is especially useful for choosing swimsuits, high-waisted bottoms, and more structured styles. For bikini bottoms with a medium, minimal cut, or side ties, the hip measurement will usually be the most important.
How to measure your hip
Measure the widest part of your hips and glutes, keeping your feet together.
The tape should be completely horizontal. This is the most important measurement for choosing bikini bottom size.
How to measure your torso for a swimsuit
For swimsuits, bust, waist, and hip measurements may not be enough. Torso length also greatly influences the fit.
Pass the tape from one shoulder, down the front of your body, between your legs, and up your back until it returns to the starting point.
A longer torso may require sizing up, even when the other measurements correspond to a smaller size.
Torso length is particularly important to prevent the swimsuit from pulling too much on the shoulders, riding up excessively in the lower area, or being loose at the waist.
How to choose your bikini top size
Bikini top size should be chosen primarily based on bust and underbust measurements.
A well-fitting top should:
- fully enclose the bust;
- keep the band stable around the body;
- not create empty spaces in the cup;
- not cut into the bust at the sides;
- allow comfortable arm movement;
- keep straps firm without digging into the shoulders.
For underwire tops, the underwire should sit below the bust and encompass the entire base, without pressing into breast tissue.
The back band should be aligned and not ride up when you lift your arms. A bikini top should fit similarly to a comfortable bra: firm, but not tight.
To find different types of support and cuts, you can explore our bikini tops sold separately.
How to choose a top for larger or heavier busts
Those seeking more support should pay attention to features such as:
- wide and adjustable straps;
- reinforced underbust band;
- underwire;
- molded or removable cups;
- adjustable back clasp;
- well-structured halter styles.
If your bust overflows the cup, creates side pressure, or isn't properly supported, try a size up or a style with more coverage and support.
How to choose your bikini bottom size
Bottoms should be chosen primarily based on hip measurement, but the cut is also very important.
A minimal, medium, wide, or high-waisted bottom can fit differently, even within the same size.
Bottoms are the correct size when they:
- fit without digging in too much;
- don't create deep marks at the sides;
- stay in place when you walk or sit;
- offer the desired coverage;
- don't create loose fabric at the front or back.
If you prefer a more comfortable fit or are between two sizes, choosing the next size up might be the best option, especially for styles without ties or side adjustments.
You can compare different cuts and coverage levels in our bikini bottoms collection.
How to choose your swimsuit size
In a swimsuit, all measurements must work together.
In addition to bust, waist, and hip, it's essential to consider torso length.
A swimsuit that is too small can:
- pull at the shoulders;
- ride up excessively in the lower area;
- compress the bust;
- create tension in the neckline;
- restrict movement.
A swimsuit that is too large can:
- create folds at the waist;
- be loose in the bust area;
- gape at the back;
- shift during wear;
- offer little support.
The swimsuit should fit snugly against the body, but allow you to walk, sit, and move your arms comfortably.
Explore our women's swimsuits and always check the size chart available for each style.
What if you wear different sizes for the top and bottom?
It's perfectly normal to wear one size for the top and another for the bottom.
Many women have, for example:
- a smaller bust and wider hips;
- a fuller bust and narrow hips;
- a preference for a more comfortable bottom;
- a need for more support in the upper part.
For this reason, most Bikinikloset bikinis allow you to purchase the top and bottom separately.
This option avoids having to choose a set where only one of the pieces fits correctly.
You can freely combine bikini tops with bikini bottoms, choosing the size and cut that best suit each area of your body.
How to tell if your bikini is the right size
After putting on your bikini, make a few simple movements:
- raise your arms;
- lean forward;
- sit down;
- walk;
- twist your torso;
- simulate a swimming motion.
The bikini should stay in place without requiring constant adjustments.
Signs that your bikini is too small
- your bust spills out from the top or sides;
- the band digs in excessively;
- the straps leave deep marks;
- the bottom cuts into your hips;
- the fabric creates too much tension;
- you feel discomfort when moving.
Signs that your bikini is too big
- there's empty space in the cups;
- the band rides up your back;
- the straps slip even after adjustment;
- the bottom forms wrinkles;
- the swimsuit gaps at the sides;
- the piece shifts easily.
What to do when you're between two sizes
When measurements fall between two sizes, the decision depends on the style, fabric, and desired fit.
You can size up when:
- you prefer greater comfort;
- the fabric is firmer;
- the style has little adjustability;
- you have a fuller bust or wider hips;
- you are choosing a swimsuit and have a long torso.
You can size down when:
- the fabric is very stretchy;
- you prefer a firmer fit;
- the style has fully adjustable straps and sides;
- the brand's chart indicates a more generous fit.
If in doubt, check the garment's features and the respective brand's chart. Do not automatically use the same choice for all styles.
Special considerations by style
Triangle tops
Triangle tops often offer plenty of adjustability through the straps and back.
They are a flexible option for those who are between sizes or prefer to adapt the cup position to their breast shape.
Underwire tops
Underwire tops should be chosen with greater attention to the cup and underbust width.
The underwire should encompass the base of the bust and never press on or end on breast tissue.
Strapless or bandeau tops
Strapless tops need to fit firmly around the ribcage.
If they are too loose, they can slip down during movement. If they are too tight, they can cause discomfort and create marks.
Tie-side bottoms
Tie-side bottoms are easy to adjust and adapt to small size differences.
The tie-side bikini bottoms allow you to adjust the hip fit and choose the rise level of the bottom.
Swimsuits with adjustable straps
Adjustable straps allow for partial correction of torso length and improved bust support.
However, they do not replace choosing the correct size. If the swimsuit pulls too much in the lower area or on the shoulders, it may be necessary to choose a size up.
Discover our swimsuit collection
Quick summary: what measurement to use?
- Bikini top: bust and underbust
- Bikini bottoms: hips
- High-waisted bottoms: hips and waist
- Swimsuit: bust, waist, hips, and torso length
- Between two sizes: consider elasticity, adjustability, and fit preference
Frequently asked questions about bikini and swimsuit sizes
Should I choose the same size I wear in clothes?
You can use your usual size as an initial reference, but you should always check the measurements and the respective brand's size chart.
The fabric's elasticity, cut, and brand origin can significantly alter the most suitable size.
Should bikinis fit tightly?
They should fit snugly because the fabric can stretch slightly when wet.
However, they should not cause pain, deep marks, excessive pressure, or restrict movement.
Can I choose a different size for the top and bottom?
Yes. At Bikinikloset, many styles are sold separately precisely to allow you to choose one size for the top and another for the bottom.
How to choose a swimsuit for a long torso?
Measure the full length of your torso and consider going up a size if the swimsuit pulls at the shoulders, rides up too much in the bottom area, or creates tension at the neckline.
Models with adjustable straps can also provide greater flexibility.
What if the size doesn't fit?
Check the exchange and return conditions and confirm that the item retains the required tags and hygienic protectors.
You can find all the information in our FAQs on sizing, exchanges, and returns.
Finding the right size makes choosing simpler
The best size is not necessarily the one you usually wear, but rather the one that offers support, comfort, and freedom of movement.
Taking measurements correctly, checking each brand's size chart, and choosing the top and bottom separately significantly reduces the risk of error.
Once you find the ideal fit, you can focus on what really matters: choosing the colours, patterns, and styles that best suit you.
Explore Bikinikloset's selection of women's swimwear and discover premium bikinis and swimsuits for different bodies, styles, and preferences.
To complement this guide, also see how to choose the ideal bikini for your body type.
