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Getting 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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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.

4 Straps

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 cup size if:

    • The wires are digging into your breast tissue
    • The wires are lifting away from your breastbone

    Go down a cup size if:

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

    • Your breasts are spilling out of the cups at the front or under the arms

    Go down a cup 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

caring for your bra

Looking after your bra will help maintain its fit over time.

  • Wash at 40°C
  • 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
  • Line dry padded bras to avoid distorting the cups
  • 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, twist one cup inside the other