How to measure your bra size at home accurately
Most women in Japan are wearing a bra size that was last measured in a shop years ago, often by a fitter using a method that prioritises the sizes the shop stocks rather than the sizes that actually fit. Measuring yourself at home takes about five minutes and gives you numbers you can use for any made-to-measure order.
What you need before you start
A soft tape measure, a mirror, and ideally a non-padded bra you already find comfortable. Avoid measuring over a padded bra because the padding adds volume to the bust measurement and throws off the cup calculation. If you do not own a non-padded bra, measure without a bra and add one centimetre to the full bust measurement.
Taking the underbust measurement
Wrap the tape measure around your ribcage directly under the bust. Keep it level and snug but not tight enough to compress the skin. Breathe out normally and read the measurement. This is your band size. In Japanese sizing, band sizes run in increments of five (65, 70, 75, 80, 85, 90, 95, 100). Round to the nearest increment.
If you measure 77 cm, your band is 75. If you measure 79 cm, your band is 80. When in doubt between two sizes, the tighter band gives more support and is generally the better choice for underwired bras.
Taking the full bust measurement
Lean forward slightly so the breast tissue falls away from the chest wall, then wrap the tape around the fullest part of the bust. Keep the tape parallel to the floor. This is your full bust measurement.
The difference between your full bust and your underbust gives you the cup size. In Japanese and European sizing: 10-12 cm difference is an A cup, 12-14 cm is B, 14-16 cm is C, 16-18 cm is D, 18-20 cm is E, 20-22 cm is F. So a woman with an underbust of 80 cm and a full bust of 96 cm would be an 80D.
Cup projection and why it matters for lace bras
Standard cup sizing assumes a certain breast shape, but projection (how far the breast extends from the chest wall) varies significantly between women with the same cup volume. A woman with a 75D and high projection will find that a standard three-part cup sits away from the chest at the top, creating a gap.
For made-to-measure orders at Platinum Stat, we ask for a projection measurement: stand sideways against a wall, hold the tape from the chest wall to the fullest point of the bust. This number helps us adjust the cup depth before cutting.
These measurements are a starting point. Fit also depends on wire width, cup shape, and strap placement, all of which vary between styles. If you are unsure after measuring, use the enquiry form and we can advise before you order.