Measuring at home is almost always kinder than measuring in a shop, and for a first bra it is just as accurate. You need a soft tape measure, a mirror, and about five minutes. Nothing about it should feel like an examination.
Let her keep a close-fitting t-shirt on. There is no need for her to undress, and the small difference a thin cotton layer makes is far less important than her feeling comfortable. If she would rather measure herself with you reading out the steps, that is a perfectly good version of this.
The first measurement is the underbust, sometimes called the band. Pass the tape around her ribcage directly beneath the bust, keep it level all the way round, and pull it snug but not tight. She should be able to breathe normally with the tape in place. Write the number down.
The second is the chest, taken loosely around the fullest part. This one should not be pulled tight at all — let the tape rest. Keep it level front and back, which is where the mirror helps.
Now compare the two numbers. If they are within roughly two centimetres of each other, stretch sizing (XS to L) is the easiest and most forgiving place to start, and it is what most first bras and bralettes use. A bigger gap between the two suggests she may be ready for a bra with defined cups, though still soft and wire-free.
Two small refinements make a real difference. Measure in the evening if you can, because bodies swell slightly through the day and a bra that is comfortable at seven in the evening will be comfortable all day. And if she lands between two sizes, size up. Growing bodies catch up with a size in a season, and a band that bites is the fastest way to make a bra unwelcome.
When it arrives, the fit test is simple. The band should sit level and stay put when she raises her arms, with room to slide two fingers underneath. Straps should lie flat without digging into her shoulders. The fabric should be smooth, with no gaps and nothing spilling. If she has forgotten she is wearing it by lunchtime, you got it right.
Keep the tape measure somewhere findable. At this age she may need a new size within six months, and re-measuring is a two-minute job once you have done it once.
with love, loomela
