how to measure blinds

How to measure Blinds



Tape Measure


Measuring your windows for Blinds, Shades or Interior Shutters is easy. Let’s start with a few general rules that apply to all of the window treatments we sell. Remember, it’s best to measure TWICE and order ONCE.

  1. Always use a steel tape measure. We prefer the Stanley Fat Max Tape Measure. Never try to measure your windows with a cloth tape, ruler or yardstick. Please look at video below “How to read a tape measure.
  2. Measure down to the nearest eighth of an inch (nearest 1/8) and do not round your measurements. Meaning don’t measure 35 3/8″ and call it 35″ or 36″.
  3. When writing down your measurements be sure to indicate which measurement is the width and which is the height and ALWAYS note the width first, then the height. A common mistake customers make is transposing the numbers. Be sure not to get them backwards. Since these are custom made products it’s generally very hard to have a size modified and can get costly to have them remade.
  4. Measuring Example: your window is 36 3/8″ wide by 60 1/4″ high (tall). Think of it in these terms, Width is horizontal (horizon) left to right and height is vertical top to bottom. Your written measurements would look something like this… 36 3/8″ x 60 1/4″
  5. Inside Mount Only – Do NOT take any deductions . Our factory takes those allowances. You need to provide us with your EXACT WINDOW SIZE OPENING, do not use the size of an existing blind in that window. Measure the width from the edge of the window in three area, top middle and bottom. Measure the height from the sill up to the top in three locations minimum. Left, middle, and right. If you take your own deductions and then order as an inside mount you will get a double deduction when the factory also takes an allowance meaning your window treatment will not fit properly and you will have a larger gap between the treatment and the window opening.
  6. Outside Mount Only – You need to provide the exact overall blind size needed (by adding the necessary coverage to the width and height of opening). Be sure to measure the top of the window to the outermost points. Our factory makes most outside mount blinds the exact width and height you specify. NOTE: The height includes the OVERALL blind which includes the headrail, etc. One of the few exceptions are roller shades which the width is generally made as a tip-to-tip size.
  7. Meaning the fabric width is generally smaller than the width of the roller tube and bracket tabs. Since there is generally no deductions made on outside mount blinds, do not order your blinds as an outside mount if you are installing them inside a window opening as they will not fit. The blind cannot be the same exact size as the window it will be installed in as there must be room for hardware and clearance. Outside mount applications are usually used for windows that do not have an inside area, like a patio sliding glass door for example.

Choose Inside or Outside Mount:

Before taking any measurements, step back from your window and decide if you want to mount the window treatment inside the window recess or outside on the wall or molding. For an inside mount, the window opening must have enough unobstructed depth to allow mounting. Be sure to look for obstructions like window locks, window cranks, etc.

How To Measure Inside Mount Blinds

Measure Window Frame Opening for IB Inside Bracket / Mount

Measure your window horizontally in three places: top, middle, and bottom. Order the smallest size measurement. DO NOT take any deductions, the size you order will come with a 1/2-inch deduction to allow the blind fits in your window frame properly.

The window frame needs to be at least 2 inches deep to install as inside mount

How To Measure Outside Mount Blinds

Measure 2 to 4 inches past the frame for OB Outside Bracket / Mount

Measure width of your window horizontally in three places: top, middle, and bottom. Use the largest measurement and ADD 2 to 4 inches on both sides of your window and to the length, to allow for full coverage. The size you order is the exact size you will receive.

Sometimes mounting on moldings is an option for outside mount. See the how to install a cordless faux wood blind video on how this type of install looks. We then measure the moldings exact measurement width by height.

Tip: For a flush inside mount (the blind completely recessed so that no part of the blind projects out of the opening) check that you have enough depth and make sure that if a valance is included that we make it slightly smaller than the window opening width since they are normally made an inch or two wider.


Tip: We usually recommend an inside mount whenever possible because it provides a cleaner look.

However, an outside mount can make a window appear larger or hide an unattractive window.

When you specify inside mount, we will make a size deduction to allow for operating clearance. With most products we will deduct up to 1/4″ from each side. Roller shades also have a rather large fabric and roller tube deduction (see product specs tab on product pages).

For vertical blinds there is also a height deduction of 1/4″. The deductions are made so that the blind will not rub or scratch your window frame. If you specify an outside mount, we will not take any size deductions.

Your blind will be made at the exact size you specify. So you must ADD to the opening measurement to allow for overlap and mounting brackets. When measuring, don’t be surprised if your windows are not square. It’s not uncommon and probably won’t be noticeable.

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