how to measure a door opening

How to Measure a Door Opening: A Step-by-Step Guide

By Richard MartinMarch 8, 2026

Measuring a door opening might seem like a simple task, but it's crucial to ensure the dimensions are accurate for a perfect fit. Whether you're installing a new door or hanging artwork, precise measurements will save you time and effort. Let's dive into the process, step by step.

Before you start, gather your tools: a measuring tape, a pencil, and a level. Also, consider the purpose of your measurement. Are you measuring for a new door, a frame, or to ensure a space is wide enough for a particular item? This will help you determine the most accurate approach.

Measuring Door Width

Door width is typically measured from the stop (the edge where the door meets the frame) to the opposite stop. This is the standard width of the door opening.

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However, if you're measuring for a new door, you'll need to consider the frame. Standard door frames add about 2 inches to the width, so you'll need to measure from the outside of one frame to the outside of the other.

Measuring for a New Door

If you're replacing an existing door, measure the width of the current door from stop to stop. This is the size you'll need for your new door.

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If you're installing a new door, measure from the outside of one frame to the outside of the other. This will give you the width you need, including the frame.

Measuring for a Frame

If you're measuring for a frame, you'll need to consider the reveal (the space between the door and the frame). Standard reveals are 1/4 inch, but they can vary. Measure the width of the current frame, then add the reveal to find the width you need for your new frame.

Remember to account for any trim or molding that will be added to the frame. You'll need to subtract the width of the trim from your measurement to ensure a snug fit.

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Measuring Door Height

Door height is measured from the top of the threshold (the bottom of the door frame) to the top of the frame. This is the standard height of the door opening.

However, if you're measuring for a new door, you'll need to consider the head (the space between the top of the door and the frame). Standard heads are 4 1/2 inches, but they can vary. Measure the height of the current door, then add the head to find the height you need for your new door.

Measuring for a New Door

If you're replacing an existing door, measure the height of the current door from the top of the threshold to the bottom of the head. This is the size you'll need for your new door.

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If you're installing a new door, measure from the top of the threshold to the bottom of the head. This will give you the height you need, including the head.

Measuring for a Frame

If you're measuring for a frame, you'll need to consider the head. Measure the height of the current frame, then subtract the head to find the height you need for your new frame.

Remember to account for any trim or molding that will be added to the frame. You'll need to subtract the height of the trim from your measurement to ensure a snug fit.

Always double-check your measurements to ensure accuracy. It's better to measure twice and cut once, as the saying goes. With precise measurements, you're well on your way to a perfect fit. Happy measuring!