Guide to Calculating Door Sizes

Instructions for calculating door sizes and frame sizes. How to work out clear opening sizes or reveal sizes or hole in wall sizes or door sizes if you only have one of these dimensions. 

How to work out clear opening sizes or reveal sizes or hole in wall sizes or door sizes if you only have one of these dimensions. 

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For a fire rated door:

• Add 4mm to the door width to get the reveal width
• Add 80mm to the door width to get the overall width
• Add 8mm to the door height to get the reveal height
• Add 46mm to the door height to get the overall height
• Subtract 50mm from the reveal width to get the clear opening width
• Subtract 25mm from the reveal height to get the clear opening height

For a non-fire rated door:

• Add 6mm to the door width to get the reveal width
• Add 82mm to the door width to get the overall width
• Add 10mm to the door height to get the reveal height
• Add 48mm to the door height to get the overall height
• Subtract 30mm from the reveal width to get the clear opening width
• Subtract 15mm from the reveal height to get the clear opening height

* Height calculations do not include allowance for flooring

Calculating Door Sizes Downloads

Door Size & Door Frame Measurement Guide

Blank frame order form – electronic

Blank frame order form – printable

For more information on Spartan door frames then please contact us.