A parent or guardian can help keep the tape level and comfortable.
Enter both measurements to continue.
A schematic fit diagram, scaled to your cup size.
The same two measurements
Measuring works identically at any age: a snug tape under the bust for the band, a loose tape across the fullest point for the bust, then the gap between the two numbers gives a cup letter.
cup difference = round(bust, in) − band
During active growth, both numbers can shift within a few months, so treat any result here as a helpful starting point for shopping rather than a fixed answer.
What to prioritize
Choosing a first bra
Soft, wire-free options first
Bralettes and soft-cup styles are commonly recommended as a comfortable starting point before underwire.
Room to grow, not room to swim
A little extra comfort at the band's loosest hook is reasonable, but a bra that's clearly oversized won't offer any real support.
Measure again every few months
Growth spurts can move both numbers faster than for adults, so more frequent re-measuring is completely normal.
Fit over label
If a size feels right but doesn't match a chart exactly, comfort and support should win over chasing a specific label.
Questions
Teen sizing FAQs
No — the same underbust and bust measurements apply at any age. A parent or guardian can help keep the tape level if needed.
Most guidance suggests starting with soft, wire-free styles or bralettes, since underwire is generally better suited to a body that has finished most of its growth.
More often than for adults — every few months is reasonable during active growth phases, since both band and cup can change quickly.
That's common during growth — round to the nearest available size and prioritize comfort over an exact match, sizing up if between sizes.
This tool is for clothing sizing only. Any concerns about growth, development, or discomfort are worth raising with a pediatrician rather than relying on a sizing tool.
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