How to Measure for Replacement Internal Doors

1

Grab your tools

You will need a tape measure, pen/pencil, and some paper.

2

Measure the width

Measure across the door opening (the frame, not the old door).

  • Take three measurements: top, middle, bottom.
  • Write down the smallest measurement — that’s your door width.
3

Measure the height

Measure inside the frame from floor to top.

  • Do this on both the left and right sides.
  • Use the shortest measurement — that’s your door height.
4

Measure for thickness

Open the door and measure the edge of the existing door (or the rebate in the frame if the door is gone).

Common UK internal door thicknesses:

  • 35mm (standard)
  • 44mm+ (fire door)
5

Check the swing

Stand with your back against the frame. If the handle is on your right, it’s a right-hand door. If the handle is on your left, it’s a left-hand door.

6

Match to the UK standard sizes

Most internal doors in England come in:

  • 1981mm x 610mm
  • 1981mm x 686mm
  • 1981mm x 762mm
  • 1981mm x 838mm

Choose a door that is slightly larger as doors are trimmed down to fit.

Note: We use 35mm thick standard doors and 44mm thick fd30 fire doors.