How to Measure up
for a New Door Size

JB Kind understand that it can be quite a job to source the right door size for your requirements, we know that shopping around for the perfect door and ending up with an ill-fitting door size is not what anyone wants. Follow our guide on how to measure up for a new door size to make sure that you don’t end up with a product that isn’t ideal for your situation. 

Please note that if you are buying replacement doors, DO NOT measure the existing door. You must always base your measurements on the door frame. There is an old craftsman’s expression, “measure twice, cut once”, so please bear this in mind. 

Another aspect to keep in mind when recording door measurements is the way the door opens. Stand in front of the door, so that it opens away from you, and take a note as to whether the hinges are on the right or left side of the door. Left side hinges means the door is left-hand open away, whereas right side hinges means the door is right-hand open away. 

Step 1: Measure the door width:

Take three measurements inside the door frame – at the top, middle and bottom. The widest measurement determines the width of the door. 

• Use a tape measure to understand the width of the three areas of the door frame. Run the tape measure along the width of the frame from the left to the right and record these numbers.
• The standard UK widths of doors are: 24 inches/610 mm, 27 inches/686 mm, 30 inches/762 mm, 33 inches/838 mm. 

Step 2: Measure the door height:

Measure the inside of each vertical side of the frame. The longest length determines the height required. Remember to make allowance for any floor covering. 

• Use a tape measure to understand the height of the door frame. Run the tape from the top corner to the bottom corner on each side and record the number of the longest length. 
• Remember to take into consideration that this could be a job where you will need to stand on something like a chair to reach the top of the frame, it might be an idea to make sure a family member or friend is helping you when you take these measurements. 
• The standard UK height of doors is most commonly 6’6”/1981mm but some may also be 2040mm.

Step 3: Measure the door thickness:

If you are looking to purchase replacement doors and to keep the same frames, you will need to replicate the door thickness, so make sure to take this measurement also. 

• Use a tape measure to understand the thickness of the existing door. Run the tape measure along the edge of the door and record the measurement of the thickness.
• You should also measure the rebate in the frame, where the door sits when closed.
• The recording of both measurements should be a close match and fit with one of the UK standard door thicknesses: 35 mm is the most common but some doors may also be 40mm.  NB. 45mm thickness usually refers to fire doors. 

For a more detailed breakdown of the most common door sizes read our explanation on UK standard door sizes.  If you have non-standard door size requirements, please contact us, as bespoke sizes can be made to order for some of our door ranges.