Kilgraston offers a full boarding experience to all of its girls from the age of 8 upwards.

Throughout the school boarders and day girls socialise in mixed age boarding areas. Butterstone for the Prep School, Mater for the Senior School and Barat/Swinton for the Sixth Form. For companionship the boarders live in year groups within these areas with the younger pupils staying in dormitories. From the age of 13 every girl may have her own study bedroom allowing personal space for reading, relaxing and just being herself. A member of staff is always 'on call' in each boarding area and each area has showers and baths and the Sixth Form study bedrooms have washbasins.

There are common rooms for each boarding area with a television, DVD and facilities for making hot drinks. Whilst the older girls have access to small kitchens, junior girls are supervised in the kitchen area.