BLOG

How to Measure Your Bra Size

370a3c0a 387b 4993 815a bf3e77ab58d5
How to Measure Your Bra Size – Body Secret Garden
Size Guide · Blog

How to Measure
Your Bra Size

Body Secret Garden  ·  Size Guide

Finding the perfect bra starts with knowing your true size. Many women wear the wrong size without realising it. Follow this simple guide to measure accurately and find the fit that works for you.

Step 01

Measure Your Underbust

Wrap a soft measuring tape snugly around your ribcage, directly below your bust. Keep the tape level and parallel to the floor. Breathe normally — do not hold your breath or pull the tape too tight.

Tip: The tape should be firm but comfortable — you should be able to slip two fingers underneath.
Step 02

Measure Your Bust

Measure around the fullest part of your chest, keeping the tape parallel to the floor. Do not compress the bust — let the tape rest lightly against the skin.

Tip: Stand in front of a mirror to make sure the tape is straight across your back.
Step 03

Calculate Your Cup Size

Subtract your underbust measurement from your bust measurement. The difference determines your cup size.

Difference → Cup Size:
~10cm (approx. 4") → A  |  ~12.5cm → B  |  ~15cm → C  |  ~17.5cm → D  |  ~20cm → E

Understanding Sister Sizes

When the band is too tight or too loose

Sister sizes share the same cup volume but have different band lengths. If your cup fits perfectly but the band is uncomfortable, try a sister size before giving up on a style.

Band too loose — go smaller
C32D70
→
D30E65
C32 and D30 have the same cup volume. D30 has a shorter, firmer band — ideal when the underbust feels too loose.
Band too tight — go larger
C32D70
→
B34C75
B34 has the same cup volume as C32. B34 has a longer, roomier band — ideal when the underbust feels too tight.
Key principle: When you go down a band size, go up a cup letter. When you go up a band size, go down a cup letter. The cup volume stays the same.
Bra Care · Fit Over Time

Which Hook Should You Use?

A new bra should always be fastened on the outermost hook. The elastic in the band will naturally stretch and loosen with wear and washing over time.

As the band loosens, move progressively to the inner hooks to maintain the correct, supportive fit.

Start here
Outer Hook
Use when brand new. Band is at its tightest.
After some wear
Middle Hook
Move here as the band begins to loosen.
Extended life
Inner Hook
Final adjustment when the band is fully stretched.
If you find yourself on the innermost hook with a new bra, the band may be too large. Consider sizing down in the band (and up in the cup — see Sister Sizes above).
Reference Chart

Japanese Bra Size Chart

Underbust A Cup
~10cm diff		 B Cup
~12.5cm		 C Cup
~15cm		 D Cup
~17.5cm		 E Cup
~20cm
63–67cm
Band 65		65A65B65C65D65E
68–72cm
Band 70		70A70B70C70D70E
73–77cm
Band 75		75A75B75C75D75E
78–82cm
Band 80		80A80B80C80D80E
83–87cm
Band 85		85A85B85C85D85E
✦
Still unsure about your size? Check our FAQ page for more fit advice, or visit our Size Guide for additional help.
Sizes may vary slightly between styles. If you are between sizes, we generally recommend sizing up in the band for comfort.