Replacing your entry door is a major upgrade for your home. It can completely change how your home looks and its curb appeal. But if you’re ordering your new door online, you’re probably not quite sure how to measure accurately. This guide will walk you through the measurement process step by step, whether you're replacing just the door slab or the entire unit. 

Measuring for a Door Slab Replacement  

While many homeowners opt to replace just the door slab to save money, this isn’t always advisable. If your door is very old or damaged, chances are the frame surrounding it (which we call the jamb) is also in similar condition. It’s best to completely replace the whole unit in that case. But if your door frame is in good condition and you only need to replace the door itself, follow these steps:

Step 1: Measure the Door Height

   Measure from the top to the bottom of your existing door. 

   Take three measurements: left side, middle, and right side. 

   Use the smallest of your three measurements to ensure proper fit. 

Step 2: Measure the Door Width

   Measure across the door at three points: top, middle, and bottom. 

   Again, use the smallest measurement. 

Step 3: Measure the Thickness

   Most entry doors are 1¾" thick. 

   Measure at the edge of the door to confirm. 

Step 4: Note the Hinge Locations

   Measure from the top of the door to the top of each hinge. 

   Measure hinge height and width. 

Count the number of hinges (typically three) and take note of the hinge placement. There are two common placements for standard hinges: standard or European. Standard (or American) hinge placements are spaced evenly along the height of the door unit. This looks nice and symmetrical. European hinge placement puts two of the hinges at the top of the door, which is our preferred configuration at RealCraft. Since gravity pulls the hardest at the top of the door, the European hinge placement prevents sagging and requires fewer hinge adjustments over time.

Measuring for a Complete Door Unit Replacement 

When replacing the entire door unit (including the jamb), do the steps above, as well as these additional steps: 

Measure the Rough Opening

Remove interior trim to expose the rough framing. 

Measure width between studs at three points. 

Measure height from header to floor. 

Check for Square

Measure diagonally from top corners to opposite bottom corners 

If measurements differ by more than ¼", note this for installation planning. This may mean that your house framing is not square--a common occurrence in older homes. You'll correct this in installation with shims.  

Measure Exterior Trim Gap

Measure the gap between your current door frame and siding. 

This ensures new brick mold or exterior trim will fit properly. 

Measuring for Sidelight Replacement 

Sidelights are the narrow windows flanking your entry door. To measure for replacement:  

Step 1: Measure Sidelight Glass

   Measure the visible glass area: height and width. 

   Measure from inside the frame to inside the frame.

Step 2: Measure Total Sidelight Unit

   Measure the entire sidelight frame height. 

   Measure the frame width. 

   Note whether sidelights are on one or both sides. 

   Measure thickness of the frame.  

More Door Measuring Tips 

• Always measure twice to ensure accuracy. If you get different measurements than the last time, use the smaller measurement of the two. 
• Write down all measurements immediately. 
• Consider the swing direction and handing of your door (left or right-handed). We have a blog post to help you determine that as well. For most entry doors, you’ll want them to be inswing. This is because inswing doors have the hinges on the inside of the house. Interior hinges results in better security, since burglars can't attempt to compromise them from outside.  
• Account for threshold height when measuring total height. 
• Round down to the nearest ⅛ inch for all measurements. 

Measuring your door correctly will save you time, money, and frustration during installing the replacement. If you want someone to walk you through the process, we're happy to help over the phone! Give us a call at 253-853-3815, Monday thru Friday, between 7AM-4PM Pacific Time.