How to Measure Bra Size at Home: The Complete Step-by-Step Guide
Learn a consistent at-home measurement method and use the results as a starting point for bra sizing.
Why Measurement Methods Differ
Sizing systems use different measurement conventions. Rather than treating one historical method as universally correct or incorrect, use the measurement instructions and size chart provided for the specific brand or garment.
What You Need Before Starting
- Soft measuring tape: Flexible sewing tape measured in inches or centimeters.
- Mirror: To verify that the tape remains completely horizontal and level across your back.
- Comfortable posture: Stand upright with relaxed shoulders. Do not suck in your stomach or puff out your chest.
Useful Measurements
Step 1: Loose Underbust
Place the tape directly beneath your breasts where the underwire sits (the inframammary fold). Keep the tape level across your back and pull it comfortably, as if wearing a gentle, relaxed garment.
Step 2: Snug Underbust
At the exact same position, pull the tape with moderate tension—the exact firmness you would want your bra band to hug you on its loosest clasp hook.
Step 3: Tight Underbust
Exhale completely and pull the tape as tight as you possibly can ("break the tape" tension). This identifies how much soft tissue compresses on your ribcage and prevents bands from shifting around during physical activity.
Step 4: Standing Bust
Stand tall and wrap the tape around the fullest part of your breasts, keeping the tape level. Ensure the tape touches the skin without denting or squishing breast tissue.
Optional: Leaning Bust (90 Degrees)
Bend forward at the waist so your torso is parallel to the floor. Let your breast tissue hang freely with gravity. Wrap the tape around the fullest part. This can provide additional information about breast shape and distribution, but it is not used as a universal correction factor by BraSizePRO.
Optional: Lying Bust
Lie flat on your back on a firm bed. Measure across the fullest part of your chest. This can provide another reference measurement, but it should not be treated as a universal indicator of cup size.
Entering Your Numbers Into the Calculator
Once you have your numbers, head over to the Universal Bra Size Calculator to calculate a US, UK, EU, and AU sizing starting point.
Frequently Asked Questions
Answers about sizing methods, measurements, and fit considerations.
What kind of tape measure should I use?
Use a flexible, soft fiberglass or sewing tape measure. Do NOT use a rigid metal carpenter's tape measure as it cannot conform to curved body contours.
Should I wear an unpadded bra or go braless when measuring?
Measure without a bra, or in an unlined, non-padded, non-compressing bralette. Padded or push-up bras distort measurements and will lead to an inaccurate cup calculation.
Why take leaning and lying bust measurements?
Standing alone often underestimates projected or softer breast tissue due to gravity. Leaning forward 90 degrees captures full tissue volume and root projection, while lying down measures how tissue settles naturally.
Sources & Standards
- British Journal of Sports Medicine: Assessment of breast support biomechanics and measuring reliability
- International Ergonomics Association: Anthropometric measurement methods for apparel sizing