247Sizing
Home › Clothing › Bra Size Converter
👙 Clothing

Bra Size Converter

Convert a bra size between US, UK, EU and French sizing — and see your sister sizes (same cup volume, different band). Already know your size? Convert it here; not sure of it? Use the bra size calculator.

Bands and cups convert differently. Band numbers map on a fixed scale (US/UK 34 = EU 75 = FR 90), but cup letters diverge: US doubles them (DD, DDD), UK inserts (DD, E, F, FF), EU runs straight (D, E, F). We show all three and your sister sizes so you can buy with confidence across regions.

Convert a bra size

Reading the result

  1. All four systems

    Your size in US, UK, EU and French sizing, converted from the one you entered.

  2. Sister sizes

    The same cup volume in the next band up and down — useful when a band runs tight or loose.

  3. US cup caveat

    US lettering above D varies (DD vs E, DDD vs F). If a brand uses different letters, match by the EU/UK equivalent.

  4. Still unsure?

    Measure with the calculator — it's more reliable than converting a size you're not sure fits.

ⓘ Affiliate links below. As an Amazon Associate we earn from qualifying purchases at no extra cost to you.
★ Top pick · Recommended on Amazon
Soft Tape Measure

Flexible body tape for an accurate underbust and bust measurement.

View on Amazon →
Recommended on Amazon
Bra Band Extenders

Add a little room to the band without changing the cup.

View on Amazon →
Recommended on Amazon
Full-Cup T-Shirt Bra

A smooth, supportive everyday bra once you know your size.

View on Amazon →

How these conversions are calculated

We use the measurement method, not the old +4/+5 rule. The band is your snug underbust measurement in inches (to the nearest even number); the cup is the difference between your standing bust measurement and the band, one cup per inch. US cup lettering above D varies by brand (DD vs E, DDD vs F), so treat letters as a guide and use sister sizes to fine-tune the band while keeping the same cup volume.

Sources: Measurement method per r/ABraThatFits calculator methodology (band = underbust, cup = bust − band); Standard international band scale (US/UK inches → EU/FR), cross-checked retailer charts 2026; Cup-letter divergence US vs UK vs EU documented on major lingerie size charts (2026).