Joybuy Insights

Buying underwear: how to choose the right fit, fabric and pack size

You often wear underwear for hours at a time. Yet when shopping online, people still tend to look only at colour, brand or discount. This can result in a waistband that digs in, fabric that quickly loses its shape or a style that shows through your clothes.

The main pitfalls are usually easy to avoid:

  • Choosing the wrong size based solely on your clothing size: sizes vary by brand and style. Measure your waist and hips, then compare them with the size guide.
  • Marketing claims without technical details: terms such as “antibacterial”, “moisture-regulating” or “shaping” mean little without information about the material, construction and care instructions. According to the brand’s own information, a treatment may contribute to comfort, but the result is not automatically the same for every wearer.
  • Choosing a style that does not suit your clothing or intended use: thongs may be less visible under a dress, while women’s briefs offer more coverage. Boxer shorts are practical for everyday wear, but may ride up under tight trousers.

The key points when comparing underwear

1. Fit and sizing

For women’s underwear, measure both your waist and hip measurements. For men’s underwear, the waist is particularly important, but the leg opening and waistband height also affect comfort. Also check whether the style is slim fit, fitted, relaxed fit or high waist.

Look out for these signs:

  • The waistband lies flat without leaving deep marks.
  • The leg openings do not dig in when sitting or moving.
  • The fabric does not continually ride up.
  • With thongs and bikini briefs, the back stays in place.
  • With plus-size underwear, sufficient stretch is important, but too much stretch can actually provide less support.

A size guide is a useful aid, not a guarantee. If you are between two sizes, look at the elastane percentage and consider how much coverage you want.

2. Material: cotton, modal or synthetic fibres

Cotton underwear generally feels familiar and is suitable for everyday wear. Elastane provides stretch and helps the style retain its shape. A cotton blend containing, for example, 90% cotton and 10% elastane will offer a different fit from 100% cotton.

Modal feels smooth and soft. It can be comfortable under close-fitting clothing, but always check the full fibre composition. Nylon and spandex are often used for seamless underwear, shapewear and shaping underwear because they offer plenty of stretch.

Also pay attention to the finish:

  • A bonded or seamless edge may be less visible under clothing.
  • A fully lined gusset provides extra coverage.
  • A wide waistband distributes pressure better than a narrow, rigid band.
  • A longer gusset or higher waist may be more practical during your period or when using sanitary pads.

When it comes to claims about an antibacterial finish, check whether the claim appears in the product information and follow the washing instructions. Such a statement is not a medical promise.

3. Pack size and care

An underwear 3-pack is useful for maintaining an everyday supply and may offer better value per item. However, compare the price per pair and check that all the pieces have the same colour, size and design.

Care has a major effect on the product’s lifespan. Wash according to the label, use a gentle programme for delicate lingerie and avoid the tumble dryer when advised against. Hand washing is often recommended for shapewear with bonded sections. The wrong temperature or drying method can damage elastic fibres and seams more quickly.

For travel, recovery or situations where washing is difficult, disposable underwear can be practical. Dispose of it according to local waste regulations and check beforehand whether the product is intended for single use.

Our recommendations for different user profiles

Suitable for: Budget-conscious beginners
Calvin Klein 3 Pack Bikini Briefs Icon Logo

Calvin Klein 3 Pack Bikini Briefs - Icon Logo

Why it suits this profile: A 3-pack with black, grey and white women’s briefs offers variety for everyday wear. The stated composition is 90% cotton and 10% elastane.

How this product avoids the pitfall

The multipack makes the price per pair clear. The available size guide lists waist and hip measurements, so you do not have to rely on the letter size alone.

Main benefit & highlights

Three colours, a cotton-elastane blend, machine washable according to the product information and a mid-rise bikini cut.

Suitable for: Shoppers looking for premium quality
Calvin Klein 3-Pack Slim Boxers Icon Cotton Stretch

Calvin Klein 3-Pack Slim Boxers - Icon Cotton Stretch

Why it suits this profile: This men’s underwear set combines a slim fit with three neutral colours. It is ideal if you are looking for a reliable everyday base for work, leisure and travel.

How this product avoids the pitfall

The product information mentions an Infinity Bond waistband and a button-free fly. When it arrives, check that the fit matches your personal preference.

Main benefit & highlights

Cotton with elastane, three colours, machine washable at 30 °C and a close-fitting boxer-short design.

Suitable for: Specific uses & intensive users
C&S Dolemi Mao ning disposable period underwear

C&S Dolemi “Mao”ning disposable period underwear, 4 pieces

Why it suits this profile: A practical option for travel, periods or times when washing is not immediately possible. The pack contains four pieces in size M-L.

How this product avoids the pitfall

The quantity is clearly stated in the product name. Before ordering, check the size, intended duration of use and disposal instructions.

Main benefit & highlights

Four pieces per pack, side fastening according to the product name and suitable for single use.

Suitable for: Fans of minimal seams
Feelingirl Mesh Smooth Mid-Thigh Shaping Shorts

Feelingirl Mesh Smooth Mid-Thigh Shaping Shorts

Why it suits this profile: This style is designed to provide light shaping under dresses, skirts or close-fitting clothing. According to the product information, sizes range from XS to 3XL.

How this product avoids the pitfall

The description mentions light shaping, anti-slip edges and side boning. These are verifiable details alongside the general claim of a smooth silhouette.

Main benefit & highlights

62% nylon and 38% spandex in the outer layer, a mid-to-high waist and hand washing recommended for care.

Looking for more options?

We have put together a complete, up-to-date list of products that fully meet these strict selection criteria and the applicable European safety regulations.

Frequently asked questions about underwear

How often should you replace your underwear?

It depends on how often you wear it, the material and how you care for it. Replace a pair when the elastic remains stretched, seams start to come undone, the fabric becomes thin or the fit changes. Looking at the condition of the garment is more reliable than following a fixed timeframe.

Which underwear is suitable under tight-fitting clothing?

Thongs and seamless underwear generally have less visible edges. However, check the leg openings and waistband: an edge may still show if the style is too tight. Choose a colour that contrasts as little as possible with your clothing and follow the size guide.

Is disposable underwear useful for travel?

Yes, especially if you want to pack light or cannot wash clothes straight away. Check the number of pieces, the material information, the size and whether it is genuinely intended for single use. For everyday wear, washable underwear is usually more practical and creates less waste.