How to Measure Your Old Window Hardware: Complete Guide for First-Time Renovators

One of the biggest headaches in old house renovation is ordering the wrong size window hardware. You find the perfect vintage-style handle, wait two weeks for delivery, and then discover it doesn't fit your existing hole positions – that's a 30%+ return rate problem we see every day.

This guide will walk you through exactly what to measure, what tools you need, and how to avoid the most common measurement mistakes, even if you've never done this before.

What You'll Need Before You Start

You don't need fancy tools – just 3 things:

- A standard tape measure (metric preferred, as most hardware is sized in millimeters)

- A pen and paper to write down measurements

- Your old hardware (if you still have it)

Pro tip: Always measure in millimeters, not inches. Even 1mm difference can mean the difference between a perfect fit and a hardware that won't install.

Step 1: Measure the Handle Spindle Size (Most Important)

The spindle is the square metal bar that connects the handle to the window locking mechanism. This is the single most common reason for returns.

How to measure:

1. Remove the old handle from the window

2. Pull out the square spindle bar

3. Measure the width of one side of the square

4. Write down the exact measurement (most common sizes: 7mm, 8mm, 9mm)

Common mistake: Measuring diagonally instead of straight across. Always measure the flat side, not the corner.

For compatible replacement handles that fit most standard spindle sizes, check our window handles collection

Step 2: Measure the Screw Hole Distance

This is the distance between the two screws that hold the handle base to the window frame. Get this wrong, and you'll have to drill new holes in your vintage window frame – something most renovators want to avoid.

How to measure:

1. Measure from the center of the top screw hole to the center of the bottom screw hole

2. Don't measure from the edges – always measure from center to center

3. Most common sizes: 43mm, 50mm, 55mm, 65mm

Pro tip: If your old hardware is still attached, you don't even need to remove it – just measure between the screw centers right on the frame.

Step 3: Measure the Gearbox Length (For Full Mechanism Replacement)

If you're replacing the entire locking mechanism (not just the handle), you need to measure the gearbox length.

How to measure:

1. Remove the entire mechanism from the window frame

2. Measure the total length from top to bottom, including the end caps

3. Count the number of locking points (most common: 2-point, 3-point, 4-point)

For replacement gearboxes that fit most vintage window frames, see our gearbox operators collection.

Step 4: Measure Hinge Size (For Door & Window Hinges)

Replacing hinges? You need 3 key measurements:

1. Leaf height: The total height of the hinge plate

2. Leaf width: The width of one leaf when open

3. Knuckle length: The length of the central pin section

Common mistake: Forgetting to check the offset. Some vintage windows have offset hinges that sit further out from the frame than modern ones.

For high-quality replacement friction hinges, browse our friction hinges collection

The #1 Mistake to Avoid

Guessing. So many renovators think "it looks standard" and order without measuring. 9 times out of 10, they're wrong, and end up returning the hardware.

Even if you think it's a standard size, take 2 minutes to measure. It will save you 2 weeks of waiting for a replacement.

What to Do If Your Measurements Are Non-Standard

Don't panic! Many old houses have custom-sized hardware from the original construction. We regularly make custom hardware for non-standard measurements – just send us your measurements and a photo of your old hardware, and we can make an exact match.

Quick Measurement Checklist Before You Order

✅ Spindle size measured in millimeters (not inches)

✅ Screw hole distance measured center-to-center

✅ Gearbox total length measured

✅ Hinge leaf height and width noted

✅ You have photos of your old hardware ready

Check all 5 boxes, and you'll get the right hardware on the first try, guaranteed.