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Try our bra fit tool


Our handy guide has all the tips and tricks from our
in-store lingerie specialists so you can find the right bra
shape and fit from the comfort of your home.
Try our bra fit tool

Find the perfect fit

There are four key areas to focus on when
shopping for a new bra. M&S lingerie expert
Julia Mercer provides her step-by-step tips for
getting the perfect fit every time

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Key fit areas


The underband should be horizontal across your back. It should be snug but with enough room to fit two fingers underneath it


The wires at the front should sit flat at the breastbone between your breasts


Your breasts should be fully enclosed in each cup and there should be a smooth line where the cup ends


The bra straps should be secure, but not tight. If you drop the straps, the bra should stay in the same place

Problems & solutions


Go up a back size if:
• The breast tissue under your arms is bulging over the underband

Go down a back size if:
• Your breasts are showing beneath the underband
• The underband is riding up your back


Go up a back size if:
• The wires are digging into your breast tissue
• The wires are lifting away from your breastbone

Go down a back size if:
• The wires are slipping down your body, towards your waist


Go up a back size if:
• Your breasts are spilling out of the cups at the front or under the arms

Go down a back size if:
• The cups are wrinkling or gaping


Loosen your bra straps if:
• They are digging into your shoulders
• They feel tight and are causing the cups to dig into your breasts, creating a 'double busting' effect

Tighten your bra straps if:
• They are slipping off your shoulders.
• If you have narrow shoulders, avoid balcony bras as these have wide-set straps

Problems & solutions

Looking after your bra will help maintain its fit over time


• Wash at 40°C or less
• Wash light and dark colours separately
• Use a whites detergent with brightening agents to prevent greying
• Wash your bras in a delicates bag or pillowcase
• Avoid tumble drying padded bras to prevent the cups distorting
• Re-shape padded bras while damp so they dry in the right shape
• Store bras upright to avoid crushing. To help the cups keep their shape

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