How To Properly Measure Your Interior Door

How To Properly Measure Your Interior Door

In apartment buildings, openings are most often designed for standard frames. In private houses made according to individual projects, the range of doorway parameters is wide.

In any case, measurements must be made carefully and each of them should be made more than once.

When measuring, you should pay attention to certain points:

  • If there are several doors, then opening parameters must be measured for each of them.
  • It is important to clarify the composition of the wall at the doorway location. It must be strong and with stable quality, otherwise the installed construction may collapse along with a low quality and weak piece of the wall.
  • The doorway must be ready for installation. If necessary, carry out strengthening works.

High and wide openings are frequently found in halls or dining rooms. In these cases, choose a double construction.

How To Properly Measure Your Interior Door

Required Tools

To take measurements properly, you’ll need:

  • Measuring tape. With its help, you can get all parameters of the doorway with necessary accuracy.
  • Level. It is necessary in order to measure the verticality of the walls and determine if border of the top of the opening is parallel to the floor.
  • Ruler. It’s needed to measure the width of joints.
  • Notebook and a pen/pencil. It is not only measurement results that need to be recorded. For clarity, you can draw a scheme with dimensions and specify the completeness of the construction.

If you have a question “What size interior door do I need?” keep reading this guide.

tools for measurements door

How To Measure The Door

To get reliable results, make five measurements of your rough opening: take 3 measurements for the width and 2 for the height from both sides.

It's necessary to measure in three different places because the wall may not be even. There can be a difference not visually noticeable, but when you install a construction, it may not crawl through the pass because of incorrect measurement.


Opening Without the Old Frame

This method is used when the frame has already been dismantled or it has never been installed. Measurements in an empty opening are taken after flooring covering has already been laid.

The doorway should have clear, even lines without protruding areas.


  • Remove all remnants of the old frame, as well as clean the wall ends from mortar remnants.
  • Assess strength of the wall and, if necessary, additionally strengthen it.
  • The width of the opening is measured in three places. Select the shortest value.
  • At least two points are measured near the corners to avoid distortions.
  • Carefully determine the height and take the smallest value.
  • Wall thickness is measured in six places: at the top, bottom and in the middle on both sides of the pass. Choose the largest value and compare it with the frame depth. Its standard depth is 4-9/16 inches. If this value is larger than the thickness of the wall, then you need to purchase extensions.

If it’s impossible to accurately calculate the size of the frame, then all minimum values should be increased by 0,4 inch.

How To Properly Measure Your Interior Door

Slab Replacement

Sometimes customers want to replace only this part of the construction, leaving the old frame. In this case, the following measurements should be taken:

  • Width. Stretch a roulette horizontally from the left to the right edge of the door and write down results. It is important to measure only the slab itself without casings.
  • Height. Stretch a roulette vertically from the top of the slab to its bottom in two different places.
  • Thickness. Attach a ruler to the end edge in two or three places.
  • Inside height and width of the frame. This information may be useful when placing an order.

Write down the results or make a convenient scheme: this way you will see all numbers at once. 

How to Choose the Opening Side?

Before ordering the door, decide how it will open.

Rule 1. If hinges are on your right when you open a slab, then it should have a right-hand opening. If the hinges are on the left side, there should be left-hand. It doesn't matter if you're standing indoors or outside.

Rule 2. Slabs must open from a smaller room to a larger one. In a bathroom, opening outward will not take up additional space. Also, such a construction makes it safer in case someone gets sick and falls on the floor blocking the pass. Doors to the children's room should open inside. If a child closes in the room and you’ll have to urgently help him/her, then breaking the slab will be much easier if it opens inward.

Rule 3. The open slab should not block neighboring ones. This may cause inconvenience to you and family members.

Think over all these points in advance so that your family can use the door conveniently.

Standard Interior Door Size

Common sizes are 32 x 80 and 30 x 80 inches. These options are available from all manufacturers. If you have non-standard doorways, you'll have to buy a model with a higher price than the standard ones. The cheapest solutions and usually most appealing ones are those that come in common sizes. This makes them the best choice for the majority of customers.


What to Consider When Placing an Order?

Size is not the only thing you need to pay attention to when ordering a new construction. There are several things that are also important:


Interior doors have different designs. They can be minimalistic or highly decorated. When choosing design, find a model that supports or enhances the architectural style of your home and not just its current decor.

Many homeowners make a mistake of thinking only of what their houses look like presently. Choosing a model that blends with the architecture of your home allows it to blend with whatever decor you choose. You have to make a choice that will look good for years to come.



The most versatile color is white. Its advantages are in creating a feeling of lightness and freedom. White doors never clash with other interior details. 

Natural wood tones are also popular looking equally great in modern and classic interiors. Manufacturing companies offer a large palette of shades, among which you are sure to find a suitable option.



The most common material for interior doors is a solid core. It’s durable and has good soundproofing characteristics. Manufacturers also produce many models with hollow and solid wood cores. All of them vary in price.



Think about finishes you want to order and decide if they are a suitable fit for that space. Manufacturers order stained and prefinished options with polypropylen, eco or natural wood veneer, enamels, and other. Each of them has its own advantages and most suitable rooms for use. The final cost depends on your choice.



Decide if you need a completely blank slab or with glass inserts. Customers often choose the blank ones in bedrooms and bathrooms, with glass panels of different sizes in living rooms and other common places. If you want visual freedom, consider French models. They have large tempered glass inserts that transmit natural light and unite the space of the house.



You can buy a traditional swinging door or a modern sliding one. The choice depends on the size of the room, style, preferences, and budget. There are several types of sliding structures: barn, pocket, bypass, magic, bifold. Each of them has a unique design.

Barn configuration has massive fittings that give it a rough look. This model is especially suitable for loft-style interiors. In other configurations, trackers are visible only when slabs are open. Such a construction adds elegance and allows to fit them into any home.

For larger openings, order a double configuration. Both sliding and swing options look very impressive and are convenient in everyday life.



The cost of an interior door depends on its size, material, and design. For a typical single construction, you should expect to spend between $150-500, excluding delivery and installation. If you choose to have a professional install it, the final price will be $100-$300 higher depending on how complex the construction is and the number of slabs. Ordering a prehung option can save you money on installation.


The conclusion

Taking measurements yourself can be challenging because you'll have to live with whatever mistake you make. Going back to making the doorway wider or narrower will only cost you extra and waste more time.


If you create house designs for people with mobility challenges, consider using standard 36" doors. This size allows sufficient space for people using a walker or wheelchair to navigate the home freely.


If you are not sure whether you can measure yourself correctly, contact the company where you are going to place an order for help. Their specialists will come to you and take measurements so that you can be sure that the construction will fit perfectly.

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