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How to measure your bra size at home

You need a soft tape measure and two minutes. Two measurements — your band and your bust — give you your size. Here's exactly how.

Step 1 — Measure your band

Wrap the tape snugly around your ribcage, directly under your bust, level and parallel to the floor. Breathe out and read the number. Round to the nearest even number — that is your band size. So 32½″ becomes a 32 band, 33″ rounds to 34.

Step 2 — Measure your bust

Measure around the fullest part of your bust, usually across the nipples, keeping the tape level and loose — don't pull it tight or it will read small.

Step 3 — Work out your cup

Subtract the band from the bust. Each inch of difference is one cup size.

Bust − band	Cup (US)
1 inch	A
2 inches	B
3 inches	C
4 inches	D
5 inches	DD
6 inches	DDD / F
7 inches	G

Avoid the old "+4" method. Older US guides told you to add 4 or 5 inches to your underbust to get the band. That gives a band that's too loose (it rides up at the back) and pushes you into a cup that's too small — the single most common sizing mistake. Measure your true underbust and round to the nearest even number instead.

A worked example

Underbust measures 33″ → rounds to a 34 band. Bust measures 37″. The difference is 37 − 34 = 3″ → a C cup. Size: 34C.

Tips for an accurate result

Measure braless or in a thin, non-padded bra. Stand up straight with arms down. Measure at the end of the day if you can, and remeasure after any weight change, pregnancy or a few months have passed — your size shifts more than you'd think.

Frequently asked questions

How do I measure my bra size without a tape measure?

Use a piece of non-stretch string or a phone charging cable, mark where it overlaps, then measure that length against a ruler. Take both your underbust and bust this way.

Should I add inches to my underbust for the band?

No. The modern method uses your true underbust rounded to the nearest even number. Adding 4–5 inches is an outdated method that gives a band that's too loose.

How often should I remeasure?

Every 6–12 months, and after any weight change, pregnancy or new exercise routine — your band and cup can both shift.