Measure Like a Pro: How To Measure Your Window Using Your Tape Measure Housing

For the ultimate blackout and a flawless fit, precise measurements are non-negotiable when installing your UBlockout shade. While many people know the basics of measuring, few are familiar with a secret weapon built right into your tape measure: the housing length.

This guide will walk you through how to use it effectively for inside mount shades.

Tape measure 101: A Quick Refresher

Before we dig into housing length, let’s make sure you’re reading your tape correctly. Here are some of the most common markings you’ll find:

Whole inches: Longest lines, usually numbered.
Half inches (1/2"): Second-longest lines.
Quarter inches (1/4"): Mid-length lines between halves.
Eighth inches (1/8") and Sixteenths (1/16"): Shorter lines requiring close attention.

Note - Not all tape measures have all markings. Some will have up to eighths of an inch, but no sixteenths - others will only have whole and half inches. Try to use a tape measure with as many fractions as possible for the most accuracy.

Image above: On this tape measure, whole inches are marked by long vertical lines that meet the halfway horizontal line. Half inches are marked with the next longest vertical lines, quarter inches by the next longest, and so on.

What is the housing length and why does it matter?

Firstly, what is the ‘housing’?

The housing, or cartridge, is the big, chunky body of the tape measure itself - the part that you hold in your hand. It’s where the tape rolls back into when retracted.

You’ll usually find the brand name or logo on one side, and a belt clip or marking label on the opposite side.

So - what’s the ‘housing length’?

Most good quality tape measures have a built-in housing length marking. This is a small number printed or etched into the back of the tape measure housing - opposite side to the logo or brand. This marking is often located above or below the belt clip.

Flip your tape measure over to the back and take a look: if you can see a number like “3 1/8 in” - that's the size of the housing.

Image above: This tape measure has the housing length imprinted under the belt clip. It says 3 1/8 IN.

Remember - not all tape measures are built the same: if your tape measure doesn’t have this you can always stick with the card and clip method as shown in our measure guide.

Measure your window frame using the housing length

Measuring the inside of a window frame can be fiddly - especially if there’s not a lot of space to move.

Using a card or clip to stabilize the tape can work reasonably well, but for extra security, we encourage you to use your tape measure housing length.

Grab your tape measure, a ladder and your helper, and get started:

Have one person hold the end of the tape (the ‘hook’) flush against one side of the window recess.
The other person should extend the tape until the back (opposite to the tape opening) of the housing meets the wall, nice and snug.
Read the tape measure exactly where it stops.
Add the housing length (found on the back) to this reading to get your full measurement.

This means:

If your tape reads 35-⅝", and your housing length is 3 ⅛”
Add these lengths together
Your total measurement is 38-¾” - easy!

Remember, for UBlockout shades:

Always round down to the nearest 1/16" to ensure the most accurate fit.
Position the metal hook at the start of your measurement area and extend the tape until it reaches the opposite edge.
Read the measurement at exactly where the tape ends.
Don’t make any assumptions or deductions - let our team handle those details.

For the recipe to success, follow our measuring guide closely.

Measuring for UBlockout shades is designed to be easy.

This technique of using the housing length makes things even easier, ensuring you get a perfect fit for 100% blackout.

If you’re still not confident, add our measure guarantee service at checkout - just $40 per shade means you’ll be guaranteed a seamless, 100% blackout fit. In the unlikely event of any issues, we’ll replace or fix the shade so it’s perfect.