Whether you’re replacing an old door or installing a new one, getting the right measurements is crucial to ensure a proper fit. Measuring for an interior door might seem daunting at first, but with the right steps, you can confidently take accurate measurements yourself. There are two main ways to measure an interior door: from a finished framed-in opening or from a stud-to-stud opening. Below, we’ll guide you through both methods so you can select the perfect door for your space.
Measuring a Finished Framed-In Opening
If your opening is already framed in, meaning the jambs and casing are in place and you only need to replace the door while keeping the existing frame, the easiest way to measure is by using the existing door. Here’s how:
Step 1: Measure the Width
- Use a tape measure to measure the width of the door at three points: top, middle, and bottom.
- If there are slight variations in width, choose the largest measurement, as long as it is within ¼”.
- If the difference is more than ¼”, your door or frame may not be square. You may need to either adjust the frame or trim a slightly larger door to fit.
Step 2: Measure the Height
- Measure from the top to bottom on both the left and right sides of the door.
- If there’s a discrepancy, decide how tall you want the door to be based on how close it should be to the floor.
- Standard interior doors usually come in heights of 80”, 84”, 90”, or 96”.
Step 3: Measure the Thickness
- Most interior doors come in two standard thicknesses: 1-3/8” or 1-3/4”.
- Choose the thickness that matches your existing door or suits your home’s style and budget.
By following these steps, you can confidently select a door that will fit well within your existing frame.
Measuring a Stud-to-Stud Opening (For a New Frame)
If you are completely redoing the frame or installing a new door in an unfinished space, you will need to measure from the exposed studs rather than an existing frame. This method requires additional allowances for the door frame and shimming.
Step 1: Measure the Width
- Measure stud to stud across the width of the opening.
- Subtract 2 inches from the width to account for the door frame and shims.
- Round down to the nearest even number for a standard door size.
- Example: If your stud-to-stud measurement is 33”, subtract 2”, which gives 31”. Rounding down to the nearest even number, you will need a 30” wide door.
- You will need to shim the opening to bring the door jamb down to a narrower size.
Step 2: Measure the Height
- Measure from the top stud to the floor.
- Standard practice is to subtract 1-1/2 inches to account for the door frame and clearance below the door.
- If the floors are already installed, subtract 1-1/2” from the stud-to-finished-floor height.
- If the floors are not installed you can measure from the subfloor, subtract:
- 1” for the top allowance,
- 1/2” for the bottom clearance,
- Less the actual flooring material thickness.
Example Calculation:
- If your measurement from stud to subfloor is 86-3/4”, and your finished flooring is 3/4” thick:
- Subtract 1-1/2” for the frame and bottom gap.
- Subtract an additional 3/4” for the flooring.
- The final measurement would be 84-1/2”, rounded down to the nearest standard size, meaning an 84” tall door would be suitable.
Step 3: Choose the Door Thickness
- Similar to framed-in openings, you can select either 1-3/8” or 1-3/4” thick doors, depending on your preference and budget.
Additional Tips for Accurate Measurements
- Check for Squareness: If your measurements differ significantly at multiple points, use a level to check if the frame is square. If it’s not, you may need to adjust the frame before installing the new door.
- Consider the Door Swing: When ordering a new door, determine whether you need a left-hand or right-hand swing door.
- Account for Flooring: If you plan to install new flooring, measure from the subfloor and factor in the final flooring thickness.
- Double-Check Measurements: Measure at least twice to confirm accuracy before purchasing a door.
Conclusion
Measuring for an interior door yourself is a straightforward process when you follow these steps. Whether you are replacing an existing door within a framed-in opening or installing a new one in a stud-to-stud opening, taking accurate measurements is key to ensuring a perfect fit. With the right tools and a little attention to detail, you can confidently select the right door for your space. Happy measuring!
