How To Cut Window Trim with A Miter Saw

Nowadays window trim is used in almost all homes because of the advantages it brings to the table. Not only does it cover the edge between the window frame and sliding but it also adds more beauty and character to your house.

If you’re planning to install window trim in your house, you first need to cut it at an angle so that it looks neat. The easiest way to achieve that is to use a miter saw. But it can be tricky if you don’t know how to cut the proper angles accurately.

Here is a step-by-step method to cut your window trim with a miter saw.

How To Cut Window Trim with a Miter Saw

Even basic, beginner miter saws have the capabilities to easily cut trim pieces. Follow the detailed steps listed below carefully to cut window trim with a miter saw within minutes.

Step 1: Buy Window Trim

There are different types of window trims available on the market and you need to choose the one that matches the theme of your house. Make sure that you buy at least 5-10 percent more material than you think you’ll need to use. 

This is because mistakes can happen that can lead to material waste. Buying a little extra material will keep you from having to make multiple trips to get the right amount of material.

After buying window trim, place it in the area where you need to install it and wait for at least a couple of days. It’s an important step because the trim can expand and contract depending upon the climate of your house. 

A window of some days will allow the trim to acclimate to the humidity levels and temperature of your house. Waiting several weeks is even better. 

Step 2: Take Measurements

Now you’ll need to take measurements of the window where you need to install the trim. Use a measuring tape to measure the horizontal length of your window and write it down on a notepad.

Keep in mind that your window trim (once cut at an angle) will have two longer pieces and two shorter pieces. The longer pieces will run vertical, while the shorter pieces will run horizontal. 

The easiest way to determine length and width is to measure the width of your window trim. Then, multiply this by “2” and add it to the horizontal length of your window, written on the notepad.

For example, if the horizontal length of your window is 16 inches and the width of your trim is 2 inches, the correct measurement for the long points of the trim will be 20 inches.

You don’t really need to perform this calculation for the vertical sides. I’ll use the horizontal borders to take measurements for the vertical sides.

Step 3: Mark Window Trim

After taking measurements, you need to mark your window trim using a pencil. You only need to mark the measurement for the long points. For example, if the horizontal length of your window is 16 inches, you need to make a cut line at the 20-inch mark on your window trim.

Step 4: Cut Window Trim

Use the following steps to cut the trim for the horizontal and vertical borders of the window.

Cutting Trim for Horizontal Sides

Start by cutting the horizontal sides of your new window trim: 

1. Most top end miter saws come with 0 to 60 markings in both directions where “0” is in the center. It cuts the stock at a 90-degree angle. Set your miter saw to 0 and place your window trim against the fence of the machine. Make sure that your marked line is perfectly aligned with the blade of your miter saw. 
2. Clamp the window trim and turn on the device to make the cut at a 90 degree angle. According to the example that I’m following, you’ll have a 20-inch piece of the window trim.
3. Now, set your miter saw to 45 on the left side.
4. Place your window trim piece on the same side.
5. Move the blade head down, without turning it on, to make sure the blade is aligned with the top corner of the trim. If it’s not, make necessary adjustments and then clamp the trim.
6. Turn your miter saw on to make the cut at a 45 degree angle and turn off the machine.
7. Remove the clamp and slide the trim to the right side of the miter saw. Don’t flip or change the side of the trim.
8. Set the angle to 45 on the right side.
9. Clamp the trim again on the right side by making sure that the blade is aligned with its top corner.
10. Turn the miter saw on to make another 45 degree angle cut.
11. Use the same technique again to cut another window trim piece.

The steps mentioned above will allow you to cut both the top and bottom horizontal window trim pieces. The distance between their short points will be identical to the horizontal length of your window.

Cutting Trim for Vertical Sides

To take the right measurement for the vertical sides, you’ll need to first install the horizontal sides. I recommend using a nail gun to affix the horizontal window trim pieces. 

After that, measure the distance between the long points of the top and bottom trim with a measuring tape. You can choose either the right or the left side to take this measurement.

Mark your window trim using that measurement and cut two identical pieces by setting your miter saw to 0. Then you’ll need to use the same technique discussed above to cut the vertical sides at a 45-degree angle.

Step 5: Fit Opposite Miters

Use the following steps to complete the window trim installation properly.

1. Apply glue to both sides of each window trim piece that you have cut for the vertical sides.
2. Use the glue activator on the horizontal window trim pieces that you have already installed. A glue activator is an acetone-based chemical that helps the glue to dry faster. The acetone present in the glue activator allows the moisture to evaporate faster in order to accelerate the drying process.
3. Place the vertical sides in their place and secure them using a nail gun.

The glue and activator will attach the four window trim pieces together to make a complete frame. The nails will secure the entire frame and will keep it in place.

Tips to Use a Miter Saw to Cut Window Trim

The most important thing to keep in mind while using a miter saw is to ensure your security. It’s a powerful tool and you must follow the safety tips listed below while using this tool.

• Read the user’s manual of the miter saw you have to understand its functions and the right way to use it.
• The process of cutting wood with a miter saw creates a lot of dust and debris that can be harmful to your health. That’s why you must wear a dust mask or respirator.
• The small wood particles can also hurt your eyes, so you must also wear safety goggles. You can also install a dust extraction system with your machine to minimize dust and debris.
• Never wear dangling jewelry and loose clothes because they can get stuck into the spinning blade. It can lead to unwanted accidents.
• Turn off the power supply if you need to make adjustments to your machine’s blade.
• Don’t try to use a dull or damaged blade to minimize accidents, even if you need to cut a very soft material.
• Never leave your workspace without turning the machine off.
• Move the head of your miter saw down before turning it on to make sure the blade guard is working as it should be.
• Use a clamp to secure the stock instead of using your hands to avoid hand injuries.
• Wait for the guard to cover the blade before picking up the stock you just cut.
• Always grab the handle of the miter saw with your dominant hand.

Final Word

A miter saw is a great tool to make cuts at different angles. Because of this unique functionality, it’s the best tool to cut window trim. I hope this guide will help you cut your window trim easily to give your windows a great look.