How to Choose the Right Thunderpants Underwear Fit for Your Body

Quick answer

Start with your waist measurement in centimetres or inches, then pick the style that matches how you want the waistband to sit: Sky Rise for a high, tapered waist, or Pouch Boxer for a lower, roomier fit. If you are between sizes, size up for comfort. Thunderpants sizing is consistent across styles, so once you know your size you can shop confidently.

Thunderpants are made in New Zealand and have a loyal following for good reason: comfortable cuts, fun prints, and Fairtrade cotton. But with styles like Sky Rise and Pouch Boxer, plus a range of sizes, choosing the right fit can feel tricky. This guide walks you through the decision so you can order once and wear happily.

We will look at waistband height, fabric, and how to measure yourself. You will also see real product examples, like the Sky Rise Goldfish and Pouch Boxer Tangerine, to understand how each style fits different bodies and preferences.

Start with your waist measurement

Grab a soft tape measure and wrap it around your natural waist, usually the narrowest part of your torso above your belly button. Keep it snug but not tight. Thunderpants size charts list waist measurements in both centimetres and inches, so use whichever you are comfortable with. For example, the Sky Rise Scratchy size chart shows waist cm 72-82 for size S, 82-92 for M, and so on.

If your measurement falls between two sizes, choose the larger size for everyday comfort. Cotton drill and Fairtrade cotton have minimal stretch, so a little extra room helps. If you prefer a snug fit, you can size down, but be aware that high-waist styles may feel tighter around the ribs.

• Measure your natural waist, not your hip.
• If between sizes, size up for comfort.
• Check the specific size chart for each style, as some have different size ranges.

Decide on waistband height: high waist vs low rise

Thunderpants offers two main waist heights: Sky Rise, which sits high on your natural waist and tapers in at the top, and lower-rise styles like the Pouch Boxer, which sit lower on the hips. Sky Rise is great if you want full coverage and a secure feel that stays put all day. The Pouch Boxer has a double-layered pouch area for extra room in front and a lower rise.

Consider what you will wear them with. High-waist styles work well under high-waisted jeans or dresses, while lower-rise styles suit low-rise pants. If you are active, high waist may stay in place better during movement. If you prefer less coverage around the middle, go for a lower rise.

• Sky Rise: high waist, tapered, full brief.
• Pouch Boxer: lower rise, extra room in front.
• Match waist height to your outfit and activity.

Fabric and stretch: what to expect

Most Thunderpants underwear is made from 100% cotton drill or Fairtrade cotton, which breathes well but has limited stretch. That means the fit relies on accurate sizing rather than elastic give. Swimwear, like the Swim Crop Popeye, uses a nylon/spandex blend with ECONYL regenerated nylon, which has more stretch and is designed for water.

If you are used to stretchy synthetic underwear, cotton may feel firmer at first. It softens with wear and washing. For the best fit, trust the size chart and your measurements rather than assuming you need a size up for stretch.

• Cotton drill and Fairtrade cotton have minimal stretch.
• Swimwear has more stretch due to nylon/spandex.
• Wash and wear will soften the fabric over time.

Special fit considerations for men and kids

The Pouch Boxer is designed with a double-layered pouch for extra room in front. It acts as a gusset but does not reach as far back as flat-fronted styles. If you need more rear coverage, consider a different style. For kids, the Kids Original Keep NZ Green is a modest, comfortable option that stays put during play.

Kids sizes follow the same measurement approach. The Kids Original is available in sizes that correspond to age or waist measurement. If your child is between sizes, size up for room to grow.

• Pouch Boxer: extra front room, less rear coverage.
• Kids Original: modest and secure for active play.
• Size up for growing kids.

Decision rules for choosing your Thunderpants fit

• If you want a high waist that stays put: Choose a Sky Rise style like Sky Rise Goldfish or Sky Rise Scratchy. They sit on your natural waist and taper in, so they do not roll down. Best for high-waisted outfits and all-day security.
• If you need extra room in front: Choose a Pouch Boxer like Pouch Boxer Artichokes or Pouch Boxer Tangerine. The double-layered pouch provides extra space. Best for men who find standard briefs too restrictive.
• If you are between sizes: Size up for comfort. Cotton has minimal stretch, so a little extra room prevents tightness. When in doubt, go larger.
• If you are buying swimwear: Order your usual underwear size. The nylon/spandex blend has more stretch but is designed to fit the same. Stick to your undies size for swim.

Product facts to guide your choice

• Sky Rise Goldfish: SKY RISE THUNDERPANTS, an extra high waisted version of our originals. They are a very comfortable full brief that sit high on your natural waist and taper in at the top, so stay right where they are meant to all day long. If you want a secure, high-waist fit that does not roll down, this style is a strong choice. The tapered top keeps the waistband in place.
• Pouch Boxer Artichokes: The Pouch Boxer has a double layered pouched area providing extra room in the front. Because it is double layered it does act as a gusset, although it doesn't reach quite as far back as our flat fronted styles. This style suits men who need extra front room. Be aware that rear coverage is less than flat-fronted styles, so if you prefer more coverage, choose a different cut.
• Swim Crop Popeye - limited sizes: Constructed in very durable nylon/spandex Thunderpants swimwear is super comfy, just like the underwear. Stick to your undies size when ordering. For swimwear, you can order your usual Thunderpants size. The fabric has more stretch than cotton, so it will feel snug but comfortable in the water.

Who this fit guide is for

Best for

• Anyone buying Thunderpants for the first time and unsure of size
• People who want a high-waist or lower-rise option and need help deciding
• Shoppers looking for New Zealand made underwear with Fairtrade cotton

Not for

• Those who prefer stretchy synthetic fabrics for everyday wear
• People who want a low-rise, flat-front style with no pouch
• Shoppers looking for seamless or laser-cut underwear

Choosing the right Thunderpants fit comes down to measuring your waist, picking your preferred waist height, and trusting the size chart. With styles like Sky Rise Goldfish and Pouch Boxer Artichokes, there is a comfortable option for most bodies. When in doubt, size up and enjoy the lasting comfort of New Zealand made underwear.