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How to Repair a Broken Window and Cut Glass

Marc McCollough

By Marc McCollough
Updated July 13, 2026

A broken window is an annoyance but repairing it doesn’t need to be intimidating. Replacing broken plate glass in a traditional wood window is often a job a DIYer can handle. You might even be able to cut replacement glass yourself. Here’s how to do it all.

Skill

Beginner

Time

Few Hours

Key takeaways.
  • A typical DIYer can replace broken plate glass on a wood window and cut new glass to fit the repair.
  • Wear safety glasses and cut-resistant gloves.
  • Remove the window putty and broken glass.
  • Apply glazing compound to the frame and press replacement glass into the compound.
  • Install glazing points and apply glazing compound around the edge of the glass.
  • Cut glass by creating a score line on the glass with a glass cutter.
  • Lift the glass and snap it at the score line on the edge of the work surface.

Tools and Materials

Tools

Materials

Note

Product costs, availability and item numbers may vary online or by market.

Protect Yourself When Working With Glass

Use these tips on replacing broken glass and cutting glass as general instructions. Always follow the use and safety instructions for the tools and materials you use. Remember:

  • Wear safety glasses and cut-resistant gloves when working with broken glass.
  • Wear a respirator when scraping paint or putty and sanding a window frame.
  • If your home was built before 1978, the paint might contain lead, so use a test kit and consult a professional, your local health department or the Environmental Protection Agency for instructions before scraping or sanding.
  • Don’t attempt to cut tempered glass, typically identified by an etching in a corner.
  • If you’re unsure of the type of glass you have, consult a professional glazier.

How to Replace Broken Glass in a Window

The instructions below tell you how to fix a standard, wood-frame window with single-pane annealed glass, also known as plate glass. If you have a vinyl or aluminum window with broken glass, or a broken double-pane window, see our window repair project for tips.

Step 1: Remove the Glazing and Remaining Glass

  1. Pull any loose glass from the frame.
  2. Carefully scrape and pry out the putty from the window pane with a painter's multi-tool.
  3. If the putty is hardened and won’t come loose, use a heat gun to soften it and try scraping again.
  4. Pull out the old glazier points with pliers.
  5. Carefully pull any remaining glass from the frame.
  6. Lightly sand the wood, making sure that it is clean and the groove is clear of debris.
  7. Use a small brush to sweep any debris away from the frame and then sweep or vacuum the work area.
  8. Wrap the broken glass in paper, seal it in a plastic bag and dispose of it according to the rules for your waste collection service.

Caution

Don’t use a heat gun if you suspect the paint might contain lead.

Step 2: Size the New Glass

  1. Measure the opening and subtract 1/8 inch from the width and height to allow space for the frame to expand and contract with temperature and humidity changes.
  2. Purchase replacement glass with the same thickness as your existing glass.
  3. Have the new piece of glass cut to your measurements or cut it using the instructions below.
  4. Dry fit the glass in the frame.

Good to Know

If you purchase replacement plate glass at your local Lowe’s, a Red Vest associate can cut it to your measurements.

Step 3: Apply a Bead of Glazing Compound

Applying Glazing Putty From a Tub

  1. Apply a coat of primer to the window frame, if specified by the glazing compound instructions.
  2. Knead the putty in gloved hands to warm and soften the material.
  3. Roll it into a thin length and apply around the frame, leaving no gaps.

Applying Glazing Compound From a Tube

  1. Apply a coat of primer to the window frame, if specified by the glazing compound instructions.
  2. Cut the tube tip at a 45-degree angle and apply it with a caulk gun, leaving no gaps around the frame.

Step 4: Install the New Glass

  1. Set the glass in place and apply even pressure to push it fully into the glazing compound, ensuring there is no glass-to-wood contact.
  2. Use a putty knife to push new glazier points into the frame a couple of inches from each corner and spaced every 6 to 8 inches on small panes, or 4 to 6 inches on larger panes.
  3. Apply another layer of glazing compound over the glass and glazier points.
  4. Ensure there are no gaps and smooth the compound with a putty knife or caulk tool, sloping it up to the frame.
  5. Wipe away excess compound according to your compound instructions, before the material dries.
  6. Let the compound cure fully, then sand and paint if necessary.

How To Cut Glass

The steps below tell you how to cut a piece of annealed glass, also known as plate glass, with a glass cutter. While cutting plate glass is relatively simple, you should practice on a few pieces of scrap glass before cutting your project piece.

Caution

Don’t attempt to cut tempered glass. Tempered glass should have an etching in a corner identifying it, but if you’re unsure of the glass type, consult a professional glazier.

Step 1: Measure and Mark the Glass

  1. Place a piece of cardboard on a flat work surface to act as padding.
  2. Clean the glass with glass cleaner and a microfiber cloth and place it on the padding.
  3. Mark the replacement glass with a wax pencil or permanent marker, according to your measurements.
  4. Use a straight edge or carpenter square to connect the marks and create a straight cut line.

Step 2: Score the Glass

  1. Apply cutting oil to the glass cutter wheel, if recommended by the instructions.
  2. Place the wheel on the cut line and slowly pull the cutter toward you, applying firm, even pressure to create a score line.
  3. The cutting wheel won’t cut through the glass, but a light hissing sound indicates you’re scoring it correctly.

Tip

Try to make the cut in one smooth action. Stopping and starting again may make an uneven cut.

Step 3: Snap the Glass

  1. Move the glass so the shorter end overhangs the work surface with the score line just over the edge.
  2. Holding the long end against the work surface, lift the overhanging end a couple of inches and bring it down quickly on the edge to snap the glass.
  3. Depending on your project, you might want to sand down rough or sharp edges with 400-grit silicon carbide sandpaper.
  4. Sweep or vacuum the work area to remove any glass particles.

FAQs on Replacing and Cutting Glass