Is a 30I the same in every brand?

No - a 30I isn't identical across brands, because brands use different sizing systems and cup depths. Here's how a standard US 30I translates in the brands we track: ThirdLove 30I, Wacoal 30I, Panache 30G, Freya 30G, Elomi 30G, Glamorise 30I, b.tempt'd 30I, Fantasie 30G. SHEFIT, Kindred Bravely, ENELL size by their own chart instead of band/cup.

What are the sister sizes for 30I?

30I's sister sizes — same cup volume, different band — are 28J and 32H. Try a sister size if the band feels too tight or loose but the cup still fits.

30I Bras

What is a 30I in other brands?

324 bras tracked in 30I · 3 brands · See all I cup

Brands: Fantasie, Freya, Panache

Your 30I across brands

A 30I isn’t the same in every brand. Here’s how a standard US 30I translates across the brands we track — and how each one runs.

Brand	How it runs	Your 30I →
ThirdLove	cups run generous	30I
Wacoal	true to size	30I
Panache	true to size	30G
Freya	band runs small	30G

What is a 30I in other brands? See all 30+ brands →

Editorial buying guide

Read the 30I buying guide

Top picks, sister sizes, and how to spot a good 30I fit.

Read →

Sister sizes

28J 32H What are sister sizes?

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Your 30I across brands

Anya Riva Spot Balcony Swimsuit - Navy/Vanilla

Offbeat Side Support Bra: Rosehip

Offbeat Side Support Bra: Natural Beige

Offbeat Side Support Bra: Black

Cherish Me Molded Plunge Bra: Red Leopard

Laurine Molded Plunge Bra: Raspberry

Tailored High Apex Bra: Natural Beige

Tailored High Apex Bra: Black

Loveland Plunge Bra: Bombshell Black

Smoothing Molded Bra: Nude

Smoothing Molded Bra: Black

Lindsey Side Support Bra: Monochrome

Lucia Side Support Bra: Midnight

Pippa Side Support Bra: Wallflower

Anya Riva Balcony Swimsuit - Black

Monica Balcony Swimsuit - Sicily Print

Heidi High Apex Plunge Bra - Ruby Red

Lara Plunge Swimsuit - Aurora Blue

Monica Balcony Swimsuit - Posy Print

Deco Moulded Plunge Molded Plunge Bra: Nude

Deco Moulded Plunge Molded Plunge Bra: Black

Essentially Smooth Molded Balcony Bra: Black

Love Crush Molded Plunge Bra: Aqua Haze

Molded Balcony Bra: Natural Beige

Envisage Full Cup Side Support Bra: Natural Beige

Envisage Full Cup Side Support Bra: Black

Fusion Full Cup Side Support Bra: White

Fusion Full Cup Side Support Bra: Sand

Fusion Full Cup Side Support Bra: Evergreen

Fusion Full Cup Side Support Bra: Black

Fusion Full Cup Side Support Bra: Blush

Illusion Side Support Bra: White

Illusion Side Support Bra: Sky

Illusion Side Support Bra: Navy

Illusion Side Support Bra: Natural Beige

Illusion Side Support Bra: Black

Illusion Side Support Bra: Blush

Rocha Non Wired Bra - Misty Rose

Tango Balcony Bra - Honey

Tango Balcony Bra - Blush

Tango Balcony Bra - Black

Allure Demi Plunge Bra - Black/Latte

Rocha Non Wired Bra - Black

Offbeat Molded Bra: Rosehip

Tailored Molded Plunge Bra: Dark Sapphire

Loveland Molded Spacer Bra: Bombshell Teal

Demure Molded Non Padded Bra: Fig

Clara Full Cup Bra - Orchid/Red

Starlight Molded Bra: Rosewater

Starlight Molded Bra: Caramel

Starlight Molded Bra: Black

Idol Molded Balcony Bra: Coffee Roast

Idol Molded Balcony Bra: Cinnamon

Quinn Molded Spacer Bra: Cameo

Quinn Molded Spacer Bra: Black

Posie Longline Bra: White

Tailored Molded Plunge Bra: Natural Beige

Tailored Molded Plunge Bra: Black

Loveland Molded Spacer Bra: Bombshell Black

Idol Molded Balcony Bra: White