How to Measure for Made to Measure Blinds – Don’t Make My $500 Mistake

Last Updated: May 2026 | Originally Published: April 2026

Learn how to measure for made to measure blinds the right way. Step-by-step guide for inside/outside mounts + free printable checklist. Avoid $500 mistakes.

Here is what I learned the hard way:

• I measured only once. My window was not square. The blinds did not fit. Cost me $500.
• I used a cloth tape measure. It stretched. My measurements were wrong.
• I forgot to check for obstructions (tile, handles). The blinds hit them.

Who this guide is for: Homeowners and renters who want to measure correctly the first time.

Who this guide is NOT for: People hiring professional measuring service (35−50) – worth it if you are unsure).

Why Most People Measure Wrong (And How to Avoid It)

Here is a truth no one told me before I wasted my money: Measuring for made to measure blinds is easy – but measuring wrong is even easier.

I learned this the hard way.

My first attempt at ordering made to measure blinds ended in disaster. I measured my living room window once. Just once. I assumed my window was perfectly square. It was not.

The blinds arrived. I tried to install them. They did not fit.

The company refused a return because the blinds were custom made. I was out $500.

That mistake taught me exactly how to measure correctly. I have now measured and installed blinds in 12 windows across my home. I have timed myself. I have made every mistake so you do not have to.

This guide is what I wish someone had given me before I wasted that $500.

Follow these steps exactly. Measure three times. Order once.

Internal link: Once you have your measurements, see my Made to Measure Blinds Buying Guide for recommendations on which blinds to buy.

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The $500 Mistake – What I Did Wrong (So You Do Not)

Before I teach you the right way, let me show you exactly what I did wrong.

My Mistake	What Happened	How to Avoid
Measured only once	My window was 0.25 inches wider at the middle than the top. The blind did not fit.	Measure at three points (top, middle, bottom). Use the smallest.
Used a cloth tape measure	Cloth stretches. My measurements were off by 0.125 inches. That was enough.	Use a steel tape measure. Always.
Forgot to check depth	Inside mount requires 2+ inches of depth. My window had 1.5 inches.	Check depth before choosing mount type.
Did not check for obstructions	A tile edge blocked the blind from sitting flush.	Look for handles, locks, tiles, and cranks before measuring.
Subtracted “for clearance”	I subtracted 0.25 inches “just in case.” That created a gap.	Do NOT subtract anything. Ever.

The worst part: I knew I should measure three times. I was just impatient. Do not be impatient. Take the extra 5 minutes. It is cheaper than $500.

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What You Will Need to Measure for Made to Measure Blinds

Before you start, gather these tools. Do not improvise.

Tool	Why It Is Important	What to Avoid
Steel measuring tape	Does not stretch. Accurate to 1/16 inch.	Cloth tape (stretches over time)
Pencil and paper	Record measurements immediately.	Relying on memory
Step ladder	Reach high windows safely.	Stretching or standing on furniture
Level (optional)	Check if window frame is square.	Not needed for basic measuring, but helpful

Pro tip: Buy a steel tape measure at Home Depot or Lowe’s for $10-$10−15. It will last forever. The cloth tape measure in your sewing kit is not for windows.

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Step 1 – Decide Inside Mount vs. Outside Mount (This Changes Everything)

This is the most important decision you will make. Your mount type determines how you measure and what measurements you submit.

Inside Mount

Feature	Detail
Best for	Windows with deep recess (at least 2 inches depth)
How it looks	Blind fits inside the window frame
Light gaps	Minimal (small gaps on sides)
Depth required	Minimum 2 inches

Choose inside mount if:

• Your window has at least 2 inches of depth (measure from glass to edge of frame)
• You want a clean, built-in look
• You do not need complete blackout
• You are installing on standard rectangular windows

Outside Mount

Feature	Detail
Best for	Shallow windows, blackout needs, sliding doors
How it looks	Blind mounts on wall above window
Light gaps	None (covers entire frame)
Depth required	None

Choose outside mount if:

• Your window has less than 2 inches of depth
• You want complete blackout (no light gaps)
• You are covering a sliding glass door
• Your window frame has obstructions (handles, tiles, cranks)

My Recommendation Based on Room

Room	Recommended Mount	Why
Bedroom	Outside mount	Complete blackout for sleep
Living room	Inside mount	Cleaner, built-in look
Kitchen	Inside mount	Standard windows usually have depth
Bathroom	Outside mount	Covers tiles and obstructions
Nursery	Outside mount	Maximum blackout for naps
Sliding door	Outside mount	Covers entire door frame

Still unsure? See my detailed Inside vs Outside Mount guide.

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Step 2 – How to Measure for Inside Mount (Step-by-Step)

Measuring Width

Follow these steps exactly. Do not skip any.

Step 1: Measure the width of your window at the top of the opening. Record this number.

Step 2: Measure the width of your window at the middle of the opening. Record this number.

Step 3: Measure the width of your window at the bottom of the opening. Record this number.

Step 4: Use the SMALLEST of these three measurements.

Step 5: Do NOT subtract anything. Do NOT round down or up. The manufacturer will make the necessary adjustments.

Real example from my living room:

Position	Measurement
Top of window	34.5 inches
Middle of window	34.75 inches
Bottom of window	34.5 inches
Order width (smallest)	34.5 inches

Why use the smallest measurement? Windows are rarely perfectly square. Using the smallest measurement ensures the blind will fit at the narrowest point. If you used the largest measurement (34.75 inches), the blind would be too wide for the top and bottom.

Measuring Height

Step 1: Measure the height from the top of the window opening to the window sill at the left side. Record this number.

Step 2: Measure the height at the center of the window. Record this number.

Step 3: Measure the height at the right side of the window. Record this number.

Step 4: Use the SMALLEST of these three measurements.

Real example from my living room:

Position	Measurement
Left side	48 inches
Center	48.25 inches
Right side	48 inches
Order height (smallest)	48 inches

Check Depth (Critical for Inside Mount)

Inside mount requires at least 2 inches of depth for most blinds.

How to measure depth:

1. Place your steel tape measure against the glass of your window
2. Measure to the front edge of the window frame
3. Record the depth in inches

Depth requirements by blind type:

Blind Type	Minimum Depth Required
Roller blinds	1.5 inches
Roman shades	2 inches
Cellular shades	1.5 inches
Faux wood blinds	2 inches
Vertical blinds	3 inches (headrail clearance)

If you have less than 2 inches of depth: You cannot use inside mount. Switch to outside mount. Do not try to force it.

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Step 3 – How to Measure for Outside Mount (Step-by-Step)

Outside mount is actually simpler than inside mount because you are not constrained by the window frame dimensions.

Measuring Width

Step 1: Measure the width of your window frame (from left edge to right edge).

Step 2: ADD 4-6 inches TOTAL (2-3 inches on each side).

Formula: Window frame width + 4 to 6 inches = Order width

Real example from my sliding door:

Window Frame Width	Add	Order Width
71.5 inches	+ 4-6 inches	75.5-77.5 inches

Why add extra width? The blind needs to extend beyond the window frame on both sides to block light completely. The more you add, the better the light blockage.

Pro tip by application:

Application	Add to Each Side	Total Added
Standard light control	2 inches	4 inches
Good blackout	3 inches	6 inches
Maximum blackout (bedrooms)	4 inches	8 inches

Measuring Height

Step 1: Measure from the top of the window frame to the bottom of the window sill (or floor for floor-length blinds).

Step 2: ADD 4-6 inches TOTAL (2-3 inches above the frame, 2-3 inches below).

Formula: Window frame height + 4 to 6 inches = Order height

Real example from my sliding door:

Window Frame Height	Add	Order Height
80 inches	+ 4-6 inches	84-86 inches

Pro tip for sliding glass doors: Measure from the top of the door frame to the floor. Add 2-4 inches above the frame. The blind should hang to within 1/2 inch of the floor (allows door to slide without dragging).

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Step 4 – Printable Measuring Checklist

Copy this checklist and use it for every window. Take it with you to the window – do not rely on memory.

text

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Step 5 – Common Measuring Mistakes to Avoid

I made most of these myself. Learn from my errors.

#	Mistake	Why It Is Wrong	How to Avoid
1	Using a cloth tape measure	Cloth stretches, giving inaccurate measurements	Use a steel tape measure
2	Measuring only one spot	Windows are rarely perfectly square	Measure at three points (top, middle, bottom)
3	Forgetting to check for obstructions	Handles, locks, cranks, and tiles can block the blind	Check the entire window area before measuring
4	Subtracting measurements	Manufacturers build in tolerances – you will create gaps	Do NOT subtract anything
5	Rounding down	If your window is 35.75 inches, ordering 35.5 inches will be too narrow	Use the exact measurement
6	Inside mount with insufficient depth	Blind will not fit inside the frame	Check depth before choosing mount type
7	Not accounting for baseboards	Outside mount must clear baseboards	Measure from the wall, not the frame
8	Assuming all windows are the same size	Construction variance of 1/4 to 1/2 inch is common	Measure each window individually

The most expensive mistake: Measuring only once. I did this. It cost me $500. Do not do this.

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Step 6 – What to Do If You Are Unsure

If you have any doubt about your measurements, do not guess. You have three options.

Option 1: Free Phone Consultation

Most online blind companies offer free measuring consultations:

Company	Service	Cost
Blindster	Phone consultation with measuring expert	Free
SelectBlinds	Video call with design consultant	Free
Blinds.com	Measuring guide + customer support chat	Free

Option 2: Professional Measuring Service

For a small fee, you can have a professional come to your home and measure your windows:

Provider	Cost	Notes
Lowe’s	$35-$35−50	Includes consultation
Home Depot	$35-$35−50	Applies toward purchase
TaskRabbit	$40-$40−80	Independent handyman

Option 3: Pay for Professional Measuring

If you are unsure, pay for professional measuring. It costs $35-$35−50 and saves you from ordering $500 worth of blinds that do not fit.

The math: $50measuringfeevs\mathrm{.}$50measuringfeevs.500 in blinds that cannot be returned. Professional measuring is cheap insurance.

Ready to order? See my Made to Measure Blinds Buying Guide for recommendations.

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Installation – What to Expect After Measuring

Once you have your measurements and have ordered your made to measure blinds, installation is the next step.

What you will receive:

• Your custom blinds (cut to your exact measurements)
• Mounting brackets (2-4 per blind)
• Screws and hardware
• Installation instructions
• Valance (decorative cover)

Installation time: 15-30 minutes per window

Tools you will need:

• Drill with screwdriver bit
• Level (do not skip this)
• Pencil
• Step ladder

Basic installation steps:

1. Mark bracket positions using your measurements
2. Level the brackets
3. Screw brackets into the window frame or wall
4. Snap the blind into the brackets
5. Install the valance
6. Test operation

For detailed installation instructions, see my How to Install Made to Measure Blinds guide (coming soon).

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Maintenance – Keeping Your Blinds Clean

Proper maintenance extends the life of your made to measure blinds.

Weekly maintenance (5 minutes):

• Dust with microfiber cloth or vacuum with brush attachment
• Close slats fully before dusting (for blinds with slats)

Quarterly maintenance (30 minutes):

• Wipe down roller blinds with a damp cloth
• Vacuum roman and cellular shades (do not use water)
• Check for any loose brackets or hardware
• Test operation (raise and lower fully)

Annual maintenance (1 hour):

• Deep clean according to blind type (see table below)
• Tighten any loose screws
• Lubricate mechanisms if needed (silicone spray)

Cleaning by blind type:

Blind Type	Cleaning Method	What to Avoid
Roller blinds	Wipe with damp cloth and mild soap	Submerging in water
Roman shades	Vacuum with brush attachment	Water or liquid cleaners
Cellular shades	Vacuum with brush attachment	Water or liquid cleaners
Faux wood blinds	Wipe with damp cloth, dry immediately	Excessive water
Vertical blinds	Wipe each slat, bathtub soak for deep clean	Machine washing

For detailed maintenance instructions, see my How to Clean Made to Measure Blinds guide (coming soon).

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Comparison – Inside Mount vs. Outside Mount (Which Is Right for You?)

If you are still deciding between inside mount and outside mount, here is a direct comparison.

Factor	Inside Mount	Outside Mount
Aesthetic	Clean, built-in look	Covers entire window
Light blockage	Good (small side gaps)	Excellent (no gaps)
Depth required	2+ inches	None
Best for blackout	No	Yes
Best for shallow windows	No	Yes
Installation difficulty	Easy	Easy
Works with obstructions	No (handles, tiles)	Yes (covers them)
Popularity	More common	Less common but growing

Which should you choose?

If you prioritize…	Choose…
Clean, built-in appearance	Inside mount
Complete blackout	Outside mount
Ease of installation	Either (both are easy)
Covering sliding doors	Outside mount
Windows with handles or tiles	Outside mount
Traditional look	Inside mount
Modern look	Either

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Material Guide – How Different Blinds Affect Measuring

The blind type you choose affects measurement requirements. Here is what to know.

Roller Blinds

Property	Detail
Depth required (inside mount)	1.5 inches minimum
Mount type	Inside or outside
Measuring consideration	Standard measuring applies

Cellular Shades

Property	Detail
Depth required (inside mount)	1.5 inches minimum
Mount type	Inside or outside (outside recommended for blackout)
Measuring consideration	Outside mount needs 4-6 inches added

Faux Wood Blinds

Property	Detail
Depth required (inside mount)	2 inches minimum
Mount type	Inside or outside
Measuring consideration	Heavier – ensure brackets are secure

Vertical Blinds

Property	Detail
Depth required (inside mount)	3 inches minimum (headrail clearance)
Mount type	Outside mount recommended for sliding doors
Measuring consideration	Add 4-6 inches for outside mount

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FAQ Page -Frequently Asked Questions About Measuring for Blinds

Q: Can I measure for blinds myself or do I need a professional?

A: You can absolutely measure yourself. Thousands of homeowners do it successfully every day. Just follow the steps in this guide, measure three times, and double-check your numbers before ordering. That said, if you are unsure, $50 for professional measuring is cheap insurance.

Q: What happens if I measure wrong?

A: Most made to measure blind companies do not accept returns on custom orders since the blinds are made specifically for your windows. I learned this the hard way – it cost me $500. However, Blinds.com offers a “Perfect Fit Guarantee” – they will remake blinds if you measure incorrectly. Blindster has a 100% satisfaction guarantee.

Q: Should I measure in inches or centimeters?

A: Always measure in inches. All major blind companies (Blindster, SelectBlinds, Blinds.com, Lowe’s, Home Depot) use inches for their order forms.

Q: Do I need to measure for every window separately?

A: Yes. Even if your windows look the same size, measure each one individually. Construction variance of 1/4 to 1/2 inch is common. I learned this when two “identical” windows in my living room were 0.25 inches different.

Q: What if my window is not square?

A: This is common in older homes. Use the smallest width and smallest height measurements from your three measuring points. This ensures the blind will fit even if the window is slightly out of square.

Q: Can I measure for blinds on a sliding glass door myself?

A: Yes. Use outside mount. Measure the width of the door frame. Add 4-6 inches (2-3 inches each side). Measure from the top of the door frame to the floor. Add 2-4 inches above the frame. The blind should hang to within 1/2 inch of the floor.

Q: How do I measure for blinds on a French door?

A: Measure each door panel separately. Use inside mount if the panel has depth (at least 2 inches). Use outside mount if the panel is shallow. Ensure the blind does not block the door handle.

Q: What is the most common measuring mistake?

A: Measuring only one spot. Windows are rarely perfectly square. Measure at three points (top, middle, bottom) and use the smallest measurement. I made this mistake. It cost me $500.

Q: Can I use a laser measure instead of a tape measure?

A: Yes, laser measures are accurate. But a $15 steel tape measure from Home Depot works just as well and is easier for measuring depth.

Q: Should I measure to the nearest 1/8 inch or 1/16 inch?

A: 1/8 inch is sufficient. Most blind companies ask for measurements to the nearest 1/8 inch. Do not round to the nearest 1/4 inch – that can create gaps.

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Your Action Plan (What to Do Next)

Step 1: Print the measuring checklist above or copy it to paper.

Step 2: Gather your steel tape measure, pencil, and ladder.

Step 3: Measure each window using the steps above. Measure three times.

Step 4: Double-check all measurements. Have someone else verify if possible.

Step 5: Take photos of your measurements (backup in case you lose the paper).

Step 6: Order your made to measure blinds from a trusted brand.

Step 7: Wait for delivery (7-21 days). Do not panic – custom manufacturing takes time.

Step 8: Install yourself (save $100-$100−150 per window).

Ready to choose which blind to buy? See my Made to Measure Blinds Buying Guide for recommendations.