Measuring your doors.
When measuring your doors please measure each door individually as you may have different sizes of which you have never noticed before especially if you have flush doors as they all look to be the same size. When measuring simply go to the nearest inch i.e. 29.3/4 Inches will be a 30″ door.
Doors come in two types of sizes:
Imperial
33″x 78″, 32″x80″, 30″x78″, 27″x78″, 24″x78″, 21″x 78″, 18″x 78″,15″x78″ doors are of 35mm thickness Fire doors are of 45mm thickness.
Metrics
826mm x 2040mm, 726mm X 2040mm, 626mm x 2040mm, 526mm x 2040mm,426mm x 2040, doors are of 40mm thickness