Quick answer: To measure for leggings, use a soft tape measure to take three key measurements: your waist (where you want the waistband to sit), your hips (around the fullest part of your bum) and your inseam (from your crotch to your inner ankle bone). For a sports bra, measure your underbust (snug, directly under your bust) and your bust (around the fullest part). Compare your numbers with the brand's size chart, and when your measurements fall across two sizes, size for your hips in leggings and your underbust in a sports bra.
Here's a truth the industry rarely says out loud: if your activewear doesn't fit, it's not because your body is the "wrong" size. It's because you've been guessing.
Letter sizes vary wildly from brand to brand. An XL in one store is a 2XL in another. Your measurements, though? Those are yours. They don't lie, and they don't change because a label says so.
Here's exactly how to measure for leggings, sports bras and more. Five minutes. One tape measure. Activewear that finally fits.
Key Takeaways
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Measure, don't guess. Letter sizes vary between brands; your measurements don't.
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Leggings need three numbers: waist, hips and inseam.
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Sports bras need two numbers: underbust and bust.
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Always use a soft tape measure and keep it level all the way around.
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Between sizes? Size for your hips in gym leggings and your underbust in a sports bra.
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Re-measure every few months, because strong, active bodies change.
What Do You Need to Measure Yourself for Activewear?
To measure yourself for activewear, you need a soft fabric tape measure, a mirror, fitted underwear or a non-padded bra, and something to write down your numbers. A friend helps, but you can absolutely do it solo.
Your measuring kit:
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A soft, flexible tape measure (not a metal DIY one)
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A full-length mirror, so you can check the tape stays level
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A non-padded bra, or no bra, for bust measurements
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Fitted underwear or thin leggings
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Your phone's notes app, or a pen and paper
Pro tip: Measure in the morning, when you're relaxed and not bloated after a big meal or a heavy training session. Stand tall, breathe normally and don't suck anything in. This is about accuracy, not shrinking.
How Do You Measure for Leggings?
To measure for leggings, take your waist, hip and inseam measurements with a soft tape measure. These three numbers tell you which size to choose and which leg length you need, so your gym leggings stay up, sit smoothly and end exactly where they should.
Step 1: Measure Your Waist
Wrap the tape around the point where you want your waistband to sit. For high-waisted gym leggings, that's usually at or just above your belly button. For mid-rise, it's just below. Keep the tape snug but not tight, and make sure it's level all the way around.
Curvy tip: Don't measure your "smallest" point if that's not where your leggings will actually sit. Measure where the waistband lives.
Step 2: Measure Your Hips
Stand with your feet together and wrap the tape around the fullest part of your hips and bum. Check in the mirror that the tape is level at the back, not dipping or riding up.
Curvy tip: For pear and hourglass shapes, the hip measurement is usually the most important number for gym leggings and gym tights. If you're between sizes, follow your hips.
Step 3: Measure Your Inseam
Stand straight with your feet slightly apart. Measure from your crotch down the inside of your leg to your inner ankle bone. Your inner ankle bone is where full-length leggings should end.
No help at home? Measure the inseam of a pair of leggings you already love, flat, from the crotch seam to the hem.
Step 4: Measure Your Thigh (Optional but Powerful)
Wrap the tape around the fullest part of one thigh. Not every brand lists thigh measurements, but if yours does, this number helps you avoid leggings that dig in, ride up or go sheer over strong thighs.
How Do You Measure for a Sports Bra?
To measure for a sports bra, take your underbust measurement (snug around your ribcage, directly under your bust) and your bust measurement (around the fullest part of your chest). The underbust sets your band size, and the bust helps determine your cup or overall size.
Step 1: Measure Your Underbust
Wrap the tape snugly around your ribcage, directly under your bust, where a bra band would sit. The tape should feel snug, and if you land between numbers, round up.
Why it matters: The band does most of the supporting work in a sports bra. Get this number right and everything else gets easier. Our guide to sports bras for curvy women explains why.
Step 2: Measure Your Bust
Wrap the tape around the fullest part of your bust, keeping it level across your back. Keep it relaxed, not tight, and don't flatten your chest.
Curvy tip: If you have a fuller bust, lean forward slightly at the hips while measuring. This helps capture your full measurement without the tape slipping.
What Measurements Do You Need for Each Activewear Piece?
Different plus size activewear pieces rely on different measurements. Use this quick guide.
What If Your Measurements Fall Between Two Sizes?
If your measurements fall between two sizes, choose based on the measurement that matters most for that piece: your hips for leggings and gym tights, your underbust for a sports bra, and your bust for tops.
Here's how to decide:
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Leggings and gym tights: Size for your hips. A waistband can be snug; fabric stretched too thin over your hips can go sheer.
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Sports bras: Size for your underbust. A band that's too loose rides up and loses support.
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Different sizes on top and bottom? Completely normal. Buy separates in the sizes that fit you, even in matching sets.
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Training style: If you want more compression for running or HIIT, size for a snugger fit. If you love a relaxed feel for yoga or walking, go for comfort.
Your body isn't a single letter. Shop like it. Not sure what suits your shape? Our body shape styling guide breaks it down.
What Are the Most Common Measuring Mistakes?
The most common measuring mistakes are pulling the tape too tight, letting it slip at the back, measuring over bulky clothes, sucking in and relying on old measurements.
Avoid these and you're already ahead:
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Pulling too tight. The tape should sit flat against your skin without digging in.
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A dipping tape. Always check the mirror. If the tape dips at the back, your number is off.
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Measuring over clothes. Jeans, jumpers and padded bras all add centimetres.
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Sucking in. Measure the body you'll actually move in. That body is strong and worth fitting properly.
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Using old numbers. Re-measure every few months, especially if your training has changed.
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Ignoring the size chart. Every brand fits differently. Check the chart every time.
Why Does Measuring Matter So Much for Curvy Women?
Measuring matters for curvy women because most activewear is graded up from straight-size patterns, so letter sizes often don't reflect real curves. Your measurements are the fastest way to find plus size activewear that fits your actual body.
Curvy women deserve better than guesswork. You deserve gym leggings that stay up, a sports bra that holds, and gym pants for women that move the way you move.
That's why ThickFit activewear is designed for curves from the very first sketch. Not adapted. Not stretched. Designed.
The Bottom Line
Measuring yourself takes five minutes. Getting it right changes every workout.
Grab your tape, take your numbers, and shop with confidence. Because the perfect fit isn't luck. It's knowing your body and choosing activewear made for it.
Measured for you. Made for curves. Shop ThickFit activewear.
Frequently Asked Questions
How do I measure for leggings?
Measure your waist where the waistband will sit, your hips around the fullest part of your bum, and your inseam from your crotch to your inner ankle bone. Compare these with the brand's size chart.
How do I measure my sports bra size at home?
Measure your underbust snugly around your ribcage, directly under your bust, then measure around the fullest part of your bust. Use both numbers with the brand's sports bra size chart.
Should I size up or down in gym leggings?
If you're between sizes in gym leggings, size for your hips. This gives you better coverage and keeps the fabric opaque during squats and stretches.
Can I wear different sizes on top and bottom?
Absolutely. Many curvy women wear a different size on top and bottom. Buy each piece in the size that fits your measurements.
How often should I re-measure myself for activewear?
Re-measure every three to six months, or whenever your training, fitness or body changes.