How to Measure Internal Doors: A Step-by-Step Guide
If you're planning to replace an old door or add a new internal door to your home or office, getting the size right is crucial. A door that is too big or too small will not fit properly and can cause problems. Taking accurate measurements saves you time, money, and effort while ensuring your new door looks and works exactly as it should.
In this guide, you will learn the simple steps to measure your internal door correctly. We will explain the tools you need and show you how to measure height, width, and thickness accurately. We’ll also share common mistakes to avoid so your new door fits neatly and works just the way it should.
Step 1: Measuring the Door Height
To measure the height, place your tape measure inside the door frame and measure from the top to the floor. Take three measurements at different points: left side, centre, and right side of the opening. This is important because door frames often shift over time and may not be perfectly straight. Use the longest measurement as your door height to ensure the door fits through the narrowest opening point. In the UK, most internal doors are 1981mm high, though older homes may have slightly different sizes.
Step 2: Measuring the Door Width
Doors are not always the same width from top to bottom, as it can lead to errors if the door frames are not always perfectly even. Take three measurements: top, middle, and bottom, since frames are not always perfectly even. Use the widest of these measurements as your door width. This ensures your new door fits neatly without extra trimming or planning. The most common door size in the UK is 762mm (30 inches) wide, so your new door is likely to match this standard size.
Step 3: Measuring the Door Thickness
To measure the door thickness, check either your existing door or the frame rebate where the door sits. Most internal doors in the UK are 35mm thick, although some modern or fire doors can be 40–45mm thick. Use a tape measure or caliper for accuracy. Measuring correctly ensures your new door stays in the frame and opens smoothly without rubbing against the frame or floor.
Step 4: Checking the Door Swing
To check the door swing, stand on the side where the door opens toward you. Look at which side the hinges are placed. If the hinges are on the left, it’s a left-hand door; if they are on the right, it’s a right-hand door. If the hinges are on your left side, you need a left-handed door. If they are on your right side, you need a right-handed door. Getting this right is important because it affects where the door handle goes and how the door opens in your room.
Common Mistakes to Avoid While Measuring the Door
Before ordering a new door, it’s essential to avoid common measuring mistakes that can result in a poor fit and additional work during installation.
- Measuring only one point instead of three for width and height.
- Forgetting to account for carpets, tiles, or other floor coverings.
- Measuring the replacement doors instead of the door frame opening.
- Ignoring door swing direction when noting hinge placement.
- Forgetting to check for obstructions, such as skirting boards or trims.
Key Takeaways
Measuring internal doors may seem tricky at first, but it is simple if you follow the right steps and take accurate measurements. Always measure the width and height in three places, check the thickness, and note the door swing to avoid gaps or doors that scrape the floor. Even a small mistake can cause fitting problems, so accuracy is very important.
Once you have your measurements ready, you can explore the high-quality internal doors offered by Emerald Doors. We offer a wide range of premium internal and external doors to match different styles and colors of any room. If you are unsure about the size or design, our team can guide you through the measurement process and help you choose the right door that matches your style and the design of your home.
FAQs on Measuring Internal Doors
Here are the most common questions people ask about how to measure doors inside your house:
How do I know what size interior door to buy?
To know what size interior door to buy, measure your door frame’s width, height, and thickness carefully. Note the door swing (left or right) and check for floor coverings. Compare your measurements with standard UK door sizes to choose the right fit.
Does a replacement door have to be exactly the same measurements?
No, a replacement door doesn’t have to match exactly. It should be close to your frame size, and small adjustments can be made by trimming the door or adjusting the frame for a perfect fit.
What are the standard internal door sizes in the UK?
The standard internal door size in the UK is usually 1981mm high × 762mm (30 inches) wide × 35mm thick. Some older homes or special designs may have slightly different widths or heights.
Can I replace just the interior door without a frame?
Yes, you can replace just the interior door without changing the frame, as long as the new door matches the existing frame’s width, height, and thickness. Small trimming may be needed for a perfect fit.