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Because the right fit isn't just about size — it's about feeling completely yourself.
Finding swimwear that fits beautifully shouldn't be a guessing game. Anyone who has ordered something online only to find it gaping at the bust, pulling at the hips, or simply not sitting the way it did on the model knows the frustration. Swimwear fit is genuinely more nuanced than regular clothing, and standard sizing charts can only take you so far.
IZSI designs for real bodies across a size range of XXS to 6XL, and offers custom sizing for every single piece in the collection. This guide is here to ensure every shopper walks away with measurements they can trust — whether choosing from standard sizes or reaching out for a bespoke fit.
All it takes is a soft measuring tape, a mirror, and five minutes.
What to Measure
1. Bust
Wrap the measuring tape around the fullest part of the chest, keeping it parallel to the floor. It shouldn't be pulled tight — it should lie flat and comfortable against the skin. A non-padded bralette works best, so the measurement reflects the natural shape.
Why it matters for IZSI pieces: The bust measurement guides sizing for bikini tops and one-pieces. IZSI tops — from the bandeau ring styles to the underwired balconettes — are designed to support and flatter, so an accurate bust measurement ensures the right coverage and hold.
2. Underbust
Measure directly under the bust, around the ribcage. The tape should be snug but not constricting.
Why it matters for IZSI pieces: This is especially important when considering underwired or boned styles like the Oriental Poppy Wired Bikini Top. The underbust measurement determines band fit — and a well-fitting band is what delivers real support, not just aesthetics.
3. Waist
Find the natural waist by gently bending to one side — the crease that forms is the natural waistline, usually just above the belly button. Measure around this point, keeping the tape relaxed.
Why it matters for IZSI pieces: IZSI's resortwear — from dresses to trousers and skirts — all work from this measurement. For high-waist bikini bottoms and sarongs, the waist measurement also determines how the piece sits and flatters.
4. Hips
Stand with feet together and measure around the fullest part of the hips and seat, keeping the tape parallel to the floor. This is usually about 20 cm below the natural waist.
Why it matters for IZSI pieces: This is the most important measurement for bikini bottoms, shorts, and one-pieces. IZSI bottoms range from string ties to structured high-waist cuts, and the hip measurement ensures the right fit across all silhouettes.
5. Torso Length (for one-pieces)
Start at the highest point of the shoulder, run the tape down across the bust, between the legs, and back up to the starting point. This gives the full torso measurement.
Why it matters for IZSI pieces: One-pieces need to fit the full length of the body to sit correctly. Too short and they pull; too long and they sag. If a torso length falls between standard sizes, this is exactly where IZSI's custom sizing service makes all the difference.
A Few Tips Before Measuring
- Measure over bare skin or snug underwear — not over clothes.
- Stand naturally. No sucking in or pushing out; just breathe normally.
- Write it down. Keeping measurements in phone notes means they're always on hand when shopping.
- Measure twice if unsure. A second measurement takes seconds and saves a lot of back and forth.
Between Sizes? IZSI Has You Covered.
Standard sizing was designed for a standard body — which, as everyone knows, isn't really a thing. Bodies are wonderfully varied, and IZSI was built around that reality.
If the bust falls into one size but the hips are another, or if there's a longer torso, broader shoulders, or any combination of measurements that don't map neatly onto a chart — IZSI's team is there to help. Simply DM on Instagram @izsi_india or email hello@izsi.in with measurements and the piece in mind. The team responds the same day — no long waits, no automated replies. Just two designers who genuinely want every piece to fit like it was made for its wearer.
At IZSI, it can be.
Quick Reference: Measurements Checklist
| Measurement | Where to Measure |
|---|---|
| Bust | Fullest part of the chest, parallel to floor |
| Underbust | Directly under the bust, around the ribcage |
| Waist | Natural waistline — the crease when bending sideways |
| Hips | Fullest part of hips and seat, parallel to floor |
| Torso Length | Shoulder → bust → between legs → back to shoulder |
Still unsure? IZSI loves a good sizing conversation. Reach out on Instagram @izsi_india — the team is always happy to help find the perfect fit.
Tags: swimwear fit guide, how to measure for a bikini, swimwear size guide India, custom sizing swimwear, inclusive swimwear India, IZSI size guide
