Measuring Instructions
Please be aware that your window measurements are not the same as your custom size. The custom size you order is the exact finished size you will receive. If the final product size does not match your custom size (NOT your window measurements), you are protected by either our 30-Day Refund Policy or 90-Day Redo Policy. Please refer to the policy pages for details.
To simplify the calculation process, we recently added a calculator to every product page that allows you to enter your window measurements, and the calculator will automatically calculate the custom sizes for you. We highly recommend trying this tool.
Simply click “Not sure of your custom size? Calculate from window measurements” to expand the calculator. Then, enter your window width and window height, and the custom width and custom height will be automatically calculated and filled in.
As you may have noticed, not every product supports both inside mount and outside mount options. Please refer to the “INSIDE MOUNT OR OUTSIDE MOUNT?” section for recommendations before deciding which mounting type best suits your window and personal preference.
Please read the “HOW TO MEASURE FOR INSIDE MOUNT” and “HOW TO MEASURE FOR OUTSIDE MOUNT” sections for detailed measuring instructions.
If you prefer to calculate custom sizes yourself, please refer to the “CONVERTING WINDOW MEASUREMENTS TO CUSTOM SIZES” section for step-by-step instructions.
Thank you for supporting our business. We hope you have a smooth and enjoyable experience. If you have any suggestions on how we can better support you, please feel free to contact us at: service@hestiablinds.com.
First: Understand Window Measurements and Custom Size
Before measuring, let's clarify what "Window Measurements" and "Custom Size" mean.
Important: Your window measurements ≠ your custom size. The custom size you ordered is the exact finished size you’ll receive.
| 1. WINDOW MEASUREMENTS | 2. CUSTOM SIZE (PRODUCT SIZE) |
|---|---|
|
Window Depth: How deep your window recess is.
Window Width: The horizontal distance between the left and right window frame.
Window Height: The vertical distance from the top edge down to the window sill.
|
Custom Width: The exact width you enter on our site - this will be the final product width.
Custom Height: The exact height you enter - this will be the final product height.
|
TOOLS NEEDED
A Measuring Tape (for better accuracy, we recommend using a steel tape measure rather than a soft tape measure)
A pencil (recommended for easy corrections)
MOUNT TYPES
There are two installation options: Inside Mount and Outside Mount. Your mount choice affects both installation method and the custom size you should order.
| INSIDE MOUNT | OUTSIDE MOUNT |
|---|---|
|
Installs inside the window frame for a built-in, streamlined look.
|
Installs outside the window frame or trim, covering a larger area than the window opening for increased coverage and light control.
|
INSIDE MOUNT OR OUTSIDE MOUNT?
Before making your decision based on personal preference, you should first consider window type compatibility, installation method and window depth requirements.
1.BASED ON YOUR WINDOW TYPE
Sliding windows and outward-opening windows usually support both inside mount and outside mount installations. For inward-opening windows, an outside mount is generally recommended.
| WINDOW TYPE | INSIDE MOUNT | OUTSIDE MOUNT |
|---|---|---|
| Sliding Windows | ✅ | ✅ |
| Outward-opening Windows | ✅ | ✅ |
| Inward-opening Windows | ❌ | ✅ |
2.BASED ON YOUR INSTALLATION METHOD
IMPORTANT: No-drill products must be installed inside the window frame. Therefore, outside mount installation is not supported.
| MOUNTING METHOD | INSIDE MOUNT | OUTSIDE MOUNT |
|---|---|---|
| No Drill | ✅ | ❌ |
| Drilling | ✅ | ✅ |
3.BASED ON YOUR WINDOW DEPTH
For an inside mount installation, your window must have enough depth for the product to fit securely inside the frame. Different products may require different depths. Please check the “Required Window Depth” or “Minimum Depth for Inside Mount” listed on the product page.
As a general reference, windows with approximately 2 1/2 inches of depth are suitable for most inside mount products.
| SHALLOW DEPTH | ADEQUATE DEPTH |
|---|---|
|
Recommendation: Go with an outside mount.
If the recess isn't deep enough, the headrail or valance may stick out past the frame and affect the overall look.
|
Recommendation: An inside mount can give a clean, built-in appearance.
Please check the product page for the “Required Window Depth” or "Minimum Depth for Inside Mount," as requirements vary by style.
|
HOW TO MEASURE FOR INSIDE MOUNT
If you choose an inside mount, start by checking your window depth.
To ensure your blinds sit flush and remain secure inside the frame, please refer to the “Required Window Depth” listed under “Installation Method” or the “Minimum Depth for Inside Mount” listed under “Mount Type” on the product page.
Each product has its own depth requirement, It’s important to check the product specifications before measuring.
Once your window is deep enough for the style you like, you're ready to measure:
MEASURE WINDOW WIDTH
Measure the inside of the frame at the top, middle, and bottom. Use the SMALLEST measurement as your window width.
For example:
Window Width is 22”.
Tip: You can print our Measurement Worksheet to jot everything down.
For roller and zebra shades, measuring across the top is enough to get your window width.
IMPORTANT: If you are ordering No Drill products, measuring across the top is enough to get your window width.
MEASURE WINDOW HEIGHT
Measure the inside of the frame at the left, center, and right. Use the LONGEST measurement as your window height.
For example:
Window Height is 30 1/8”.
HOW TO MEASURE FOR OUTSIDE MOUNT
If you choose an outside mount, and will be installing the product on the wall outside the window frame or trim, follow these steps:
MEASURE WINDOW WIDTH
Measure across the window (including any trim you want to cover) at the top, middle, and bottom. Use the LONGEST measurement as your window width.
For example:
Window Width is 22 1/8”.
Tip: You can print our Measurement Worksheet to jot everything down.
For roller and zebra shades, measuring across the top is enough to get your window width.
MEASURE WINDOW HEIGHT
Measure across the window (including any trim you want to cover) from top to bottom at the left, center, and right. Use the LONGEST measurement as your window height.
For example:
Window Height is 30 1/8”.
CONVERTING WINDOW MEASUREMENTS TO CUSTOM SIZES
We have added a calculator to every product page that allows you to enter your window measurements, and the calculator will automatically calculate the custom sizes for you. We highly recommend trying this tool.
Simply click “Not sure of your custom size? Calculate from window measurements” to expand the calculator. Then, enter your window width and window height, and the custom width and custom height will be automatically calculated and filled in.
If you prefer to calculate the custom sizes yourself, here are the steps:
CALCULATE FOR INSIDE MOUNT
Custom Width
Step1: Check if you window measurement is an exact 1/8" increment.
If the measurement is not already an exact 1/8" increment, round it UP TO THE NEXT 1/8".
For example,
If the shortest or top window width is measured as 22 3/16”, need to round to 22 4/16 (22 1/4)”, and 22 1/4” is the Window Width.
Step 2: Calculate based on the following formula.
Custom Width = Window Width - 1/4"
Important: For inside mount installation, the product requires a small clearance to fit properly inside the window frame, which is why the final product width should be slightly smaller than your measured window width. We generally recommend subtracting 1/4", though some products may require a different deduction. Please refer to the “Custom Size” section on the product page for the exact deduction amount.
For example,
If Window Width is 22 1/4”, after subtracting 1/4”, the Custom Width is 22”.
Custom Height
Step1: Check if you window measurement is an exact 1/8" increment.
If the measurement is not already an exact 1/8" increment, round it UP TO THE NEXT 1/8".
For example,
If the longest window height is measured as 33 5/16”, need to round to 33 6/16 (33 3/8)”, and 33 3/8” is the Window Height.
Step 2: Calculate based on the following formula.
Custom Height = Window Height
For example,
If Window Height is 33 3/8”, the Custom Height is 33 3/8”.
CALCULATE FOR OUTSIDE MOUNT
Custom Width
Step1: Check if you window measurement is an exact 1/8" increment.
If the measurement is not already an exact 1/8" increment, round it UP TO THE NEXT 1/8".
For example,
If the longest window width is measured as 22 3/16”, need to round to 22 4/16 (22 1/4)”, and 22 1/4” is the Window Width.
Step 2: Calculate based on the following formula.
Custom Width = Window Width + 4"
For example,
If Window Width is 22 1/4”, after adding 4”, the Custom Width is 26 1/4”.
Custom Height
Step1: Check if you window measurement is an exact 1/8" increment.
If the measurement is not already an exact 1/8" increment, round it UP TO THE NEXT 1/8".
For example,
If the longest window height is measured as 33 5/16”, need to round to 33 3/8”, and 33 3/8” is the Window Height.
Step 2: Calculate based on the following formula.
Custom Height = Window Height + 4"
Friendly note: Adding extra width and height provides more overlap for improved light control and coverage. Want a bolder, more "framed" look? Feel free to go even wider and taller. If you prefer a more minimal look, follow the minimum size addition listed in the “Custom Size” section on the product page.
For example,
If Window Height is 33 3/8”, after adding 4”, the Custom Height is 37 3/8”.
MEASURE FOR EXTRA-WIDE WINDOWS
If you have extra-wide windows, accurate measuring becomes even more important to ensure proper fit and smooth operation. For better light control and easier operation, we highly recommend splitting one extra-wide blind into two separate blinds to cover a single large window. This prevents the headrail from bowing over time and ensures a more balanced look.
For detailed instructions on how to measure and align two blinds for one wide window, please refer to our complete measuring guide.