How to Measure for Replacement Doors

Posted by Michael H. on 7th Jun 2023

When it’s time to replace doors in your home you will have to measure to know what size replacement door you will need to purchase/order.


When considering a new door, you will often see 2 sets of measurements: the actual unit size and the rough opening size.

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Actual Door Unit Size

The actual unit size is the size of the entire door product prehung in jambs, measured from outside edge of jamb to outside edge of jamb.

Door Rough Opening Size

Rough opening size is the size of the opening in the wall where the prehung door unit will be placed. Generally it is .5 inch greater than the actual door unit size. To measure your rough opening, measure horizontally from the inside edge of stud to inside edge of stud for the rough opening width.

Door Height

For rough opening height, measure vertically from the subfloor to the bottom edge of the head stud.