How to Cut Glass

Cutting glass requires patience, the right tools, and proper safety precautions. With some practice, you can learn to safely and accurately cut glass for a variety of projects and repairs around the home.

Selecting the Right Glass Cutter

Choosing the right glass cutter is the first step to achieving clean, precise cuts in glass. Here are the most common types of cutters used for DIY glass cutting:

Glass Cutter

This handheld tool has a small cutting wheel made of tungsten carbide. It scores the glass to create a splitting point. A glass cutter must be lubricated with cutting oil so the wheel can roll smoothly across the glass surface. It takes a steady hand and light pressure to cut consistently with a glass cutter.

Glass Pliers

Special pliers act as breaking pliers to snap off small pieces along a scored line. The jaws have a groove that applies even pressure. Glass pliers give you better control and protection from sharp edges.

Glass Scratch Awl

An awl has a sharp point for etching lines before scoring with a cutter. The etched line serves as a guide. An awl can also help start cracks at the end of a score line.

Diamond Glass Cutter

This cutting wheel has a small diamond chip. Diamond cutters don’t require oil and can score curved or circular lines. Diamond cutters are more expensive but last longer than standard tungsten cutters.

Ring Saw

A ring saw has a coated steel ring with diamond grit. It’s used for detailed curved cuts in stained glass. Ring saws spin a cutting ring around a glass circle.

Glass Nippers

Nippers have a plier-like design but small jaws with a slight overlap to nibble away excess glass. They create small inward curves and shapes along a cutting line.

Laminated Glass Cutter

Laminated glass like a car windshield requires a specialized cutter with a tungsten or diamond cutting head and a steel wheel that rolls alongside to break through the lamination.

Heavy-Duty Glass Cutter

For very thick plate glass, a specialized cutter has adjusted oil reservoirs, guide sticks, and cutting pressure to score consistently at full thickness.

How to Choose the Right Cutting Wheel

The small but mighty cutting wheel on a glass cutter does the hard work of scoring the glass surface. Paying attention to the wheel shape, diameter, angle, and sharpness will ensure smooth efficient scoring and clean breakage.

  • Opt for a tungsten carbide wheel for frequent use on most glass cutting projects. It has the optimal strength and sharpness.
  • A steel wheel is a budget option but wears out quickly. It’s best for occasional use.
  • Diamond wheels last the longest but come at a higher price. They’re recommended for regular glasswork.
  • Cutting wheels come in different diameters from 5mm to 9mm. Larger wheels roll more smoothly for straight long cuts. Smaller wheels are more precise for curved cuts.
  • A 60-90 degree angle on the cutting wheel is best to apply scoring pressure straight down into the glass.
  • Replace the wheel as soon as it starts to drag instead of rolling smoothly. Dull wheels make for ragged unsmooth cuts.

How to Use a Glass Cutter

Follow these basic steps to start scoring glass with your handheld cutter:

  1. Position the glass on a smooth, clean surface like a tabletop. You need a stable, vibration-free surface for controlled scoring.
  2. Keep your glass cutter oiled. Dip the cutting wheel in oil before starting. Oil allows the wheel to glide smoothly across the glass.
  3. Position the cutter against the edge of a straightedge guide. This helps guide straight even lines. Rulers and carpenter squares work well.
  4. Begin scoring by rolling the wheel firmly along the straightedge. Apply steady downward pressure as you roll the cutter. Let the wheel do the work.
  5. Make long, continuous scores in one pass for the cleanest cuts. Avoid stopping and starting along a score line.
  6. Score on the ‘good’ side of glass that will have the best edge after breaking. score 1-2mm into glass thickness. Deeper is not better.
  7. Follow curved patterns by pivoting the straightedge or using a freehand relaxed technique. Curve gradually, don’t make tight turns.
  8. Make multiple passes over thick glass. Turn the scoring angle 2 degrees with each pass to widen the score groove.
  9. Avoid scratching across the score line after making it. This weakens the tension you need for clean breakage.
  10. Use the same oil-dipped cutter on a glass piece for consistency. Don’t swap to other cutters mid-project.

How to Snap Glass Along a Score Line

Scoring glass is only the first step. Next you need to snap off small pieces or make larger breaks along the score line. Here are some safe and effective techniques:

For Small Pieces:

  • Place thumbs close together on either side of the score line.
  • Press thumbs away from each other while applying pressure on the score.
  • A clean snap will break glass right along the scoring path.

For Longer Breaks:

  • With scored glass on a table, use your hands to apply slight downward pressure on both sides near the score line.
  • Leverage your body weight and let the glass bend slowly until it snaps cleanly apart.
  • Alternatively, use a dowel, rubber squeegee, or snapping pliers on thicker glass.

To Make Controlled Breaks:

  • Use a scratch awl or carbide scribe to create a small chip at the score line’s endpoint.
  • Next, use pliers or gentle pressure to slowly crack the glass from the chip outward along the score.
  • This is the safest method and prevents cracks from veering off.

To Break Curves:

  • Use nippers to nip tiny shards outward from the score line. This slowly shapes the curve.
  • Alternatively, tap gently along the score with a small hammer and carbide scribe to fracture the curve incrementally.


  • Excess force or pressure in one spot, which can cause uncontrolled cracking.
  • Touching the freshly cut edges before sanding or grinding smooth.

How to Cut Circles and Holes in Glass

Cutting circular pieces of glass requires a few special tools and techniques. Here are some options for cutting holes and discs:

With a Glass Saw

  • A ring saw lets you spin a cutting ring to score a perfect circle.
  • Cut just inside your pencil line to account for the saw’s thickness.
  • Submerge glass in water to keep the saw blade wet and minimize chipping.
  • Use this method for smaller holes and discs under 12 inches.

With a Drill

  • Mark the circle and center point using a trammel point tool.
  • Drill an access hole on the waste side of glass using a carbide or diamond hole saw bit.
  • Insert a carbide rod into the drilled hole and tap to start cracks.
  • Turn the glass and continue tapping around the circle to cut out the hole or disc shape.

With Glass Nippers

  • Score the full circle lightly. Nip tiny bits outward from different points on the circle.
  • Gradually cut and nip your way around the scored line to complete the round shape.
  • Use nippers and a grozing rod for better control on detailed shapes.

With a Ring Cutting Jig

  • This tool has bearings that fit around a glass circle and guide a handheld cutter.
  • Score the perimeter and break outward from an access hole or by tapping.
  • Suction cup versions allow scoring circles on vertical or angled glass.

Tips for Round Cuts:

  • Grind and smooth the edges of cut holes and discs with a diamond pad or silicon carbide stones.
  • A bottle of cutting fluid helps lubricate carbide rods and grinding stones for smooth circles.

How to Cut Glass Bottle and Jars

Upcycling old bottles and jars requires some precise glass cutting techniques. Follow these steps:

1. Protect Hands and Eyes

  • Wear safety glasses and cut-resistant gloves when handling and breaking glass.

2. Score Bottleneck

  • Measure and mark the height where you want to cut off the bottle top.
  • Use a glass cutter to score around the full circumference at the height mark.

3. Heat Score Line

  • Use a small torch to heat the scored line, moving evenly around the bottle.
  • This helps expand the score line to ease breaking.

4. Cool and Dip in Water

  • Cool the scored line with a damp towel, then submerge the bottle neck-deep in water.

5. Snap Off Top

  • With bottle still in water, apply light pressure with a twisting motion to break off the top.
  • The water cushions and contains flying shards.

6. Smooth Rough Edges

  • Use silicon carbide sandpaper or a diamond pad to carefully smooth sharp edges.

7. Clean Bottle

  • Wash thoroughly with soap and water before using upcycled glassware.

Safety Tips:

  • Wear eye and hand protection at all stages.
  • Control direction that glass breaks.
  • Discard badly cracked or shattered bottles. Some imperfections are unsafe for reuse.

How to Cut Tempered Glass

Tempered glass is treated with heat or chemicals to create a distinct crystallized molecular structure. The tempering process makes it very strong but causes it to shatter in tiny cubed pieces rather than cracking or splitting. Cutting and drilling tempered glass takes specialized methods:

Methods to Avoid on Tempered Glass:

  • Standard glass cutters – will shatter tempered glass instead of scoring it.
  • Abrrasive wheels – cause too much pressure and shattering.
  • Lasers – heat causes tempered glass to explode.

Recommended Methods:

Specialized cutters – Use manual tungsten carbide or diamond wheel cutters designed for tempered glass. Cut slowly and lightly.

Ring saw – Submerge glass in water during cutting to minimize heat and shockwaves.

Waterjet machines – High-pressure water jet cleanly slices tempered glass. No heat or shockwaves.

CNC machines – Computer controls ensure precision cuts in tempered glass. Expensive but accurate.

Tips for Tempered Glass:

  • Never grind or smooth cut edges. This destroys tempering.
  • All cuts must be polished, flame finished, or sealed with epoxy or silicone. No exposed edges.
  • Expect chipping on edges. The cut may travel slightly from the score.
  • Budget extra material for test cuts to get the right pressure and feel.

How to Cut Laminated Glass

Laminated glass like a car windshield consists of two sheets of glass bonded together by a flexible layer of polyvinyl butyral (PVB). The PVB holds shards together if glass breaks. You’ll need a special cutting method:


  1. Mark your cut line on the top layer of glass. Use straightedges for straight cuts.
  2. Use a specialty cutter with both a cutting wheel and scoring wheel. The added wheel rolls alongside to cut through lamination.
  3. Cut through the top layer of glass first, then continue cutting to penetrate the PVB layer beneath.
  4. Go over the line a few times applying firm pressure to score through all layers.
  5. Clamp snapping pliers along the score line and snap upwards to break cleanly.
  6. For curves, make relief cuts and use snapping pliers in sections to follow the line.


  • Keep cutting wheels oiled for smooth rolling without dragging.
  • Apply firm pressure, but not too much – cutting through lamination takes finesse.
  • Use a utility knife to pick apart PVB at corners if it doesn’t snap cleanly.
  • Wear protective gear – laminated glass can have jagged layered edges when cut.

How to Cut Stained Glass

The art of cutting stained glass for leaded windows and other decorative objects requires precision and planning. Follow this process:

Choose Glass Type

  • Select transparent colored glass like cathedral or stained glass in thickness compatible with your project.
  • Avoid tempered, laminated, or frosted glass which are very difficult to cut intricately.

Plan Your Pattern

  • Design the full pattern on paper first. Measure and mark glass piece dimensions.
  • Use pieces larger than your pattern to allow for the width of lead cames between.

Prepare Glass

  • Wash glass thoroughly to remove any oily residue. Oils can deflect the cutter.
  • Plan cuts to avoid weak spots like bubbles or lines in the glass.

Cutting Techniques

  • Use a handheld glass cutter with oil to score lines just inside your paper pattern lines.
  • Snip inward curves and circles with specialty pliers or nippers.
  • Grind edges smooth with a silicon wheel. Use a grozing plier to nibble small chips for precision.

Follow With Precision

  • Aim for tight puzzle-like fit between pieces. Leaded joints hide minor gaps.
  • Match orientation of pieces to achieve desired pattern flow and color intensity through light.
  • Number pieces and lay pattern out before soldering to ensure proper placement.

How to Make Interior Cutouts in Glass

Creating custom cutout shapes within a glass piece requires careful planning and controlled cutting:

Choose Glass Type

  • Opt for thinner glass around 3/16″ thickness so interior shapes are easier to cut out cleanly.

Draw Pattern on Top Side

  • Plan the full design and mark an outline on the top side of the glass. This is your visual scoring guide.

Secure Underside for Scoring

  • Tape a paper template to the underside, matching your outlines so score lines meet. Or use a ring cutting jig for stability.

Score Top Side Lines

  • With glass secured underside, score along the outline on the top side. Follow curves gradually. Use an awl to start turns.

Create Access Hole

  • Protect hands and drill an access hole on the inside of the cutout shape using a diamond drill bit.

Tap to Break Out Shape

  • Insert a carbide rod into the drilled hole. Tap gently along scores to break glass out in the desired shape.

Smooth Edges

  • File and sand cut edges smooth and safe. Use a diamond pad for beveled polish.


  • Interior cutouts work best on straight-sided basic shapes rather than ornate curves.
  • Designs over 6 inches should have a few access holes drilled for stability while breaking out pieces.
  • Expect some trial and error on first attempts at intricate interior cutouts.

How to Cut Glass Tile

Small glass mosaic tiles require some modified cutting techniques. Here are some tips:

  • Use a pistol grip cutter for best control on small tiles. Carbide or diamond cutting wheels both work.
  • Lubricate the cutting wheel prior to scoring each tile – oil evaporates quickly from small cuts.
  • Score tiles face up with tile surface against a straightedge guide. Very light scoring pressure is needed.
  • Line several tiles up together against the straightedge and score them in sequence for efficiency.
  • Snap tiles up from the tabletop to break cleanly. Use snapping pliers or nippers on sturdier glass tiles.
  • For curved cuts, score and break tiles larger than your final shape. Then nip to the line with curved pliers.
  • Smooth rough tile edges by rubbing on a diamond pad or silicon carbide stone. Broken edges are very sharp.
  • Wash and dry tiles thoroughly after cutting to remove any oily residue before setting into mortar or adhesive.
  • Cut tiles a bit smaller than the space to allow for grout or mortar lines between.

How to Use a Glass Ring Saw

Ring saws spin a cutting ring coated in diamond grit to score circular cuts in glass. Water helps lubricate and minimize chipping. Follow these steps:

1. Mark Cut Line

Use a compass to draw the desired circle on your glass. Account for the width of the cutting ring in your radius.

2. Set Up Saw

Attach blade guard and proper diameter cutting ring. Fill water tray. Plug in and ensure ring spins smoothly.

3. Position Glass

Place glass over tray opening and hold firmly in place. Align your cut line with the blade.

4. Make Cut

Slowly lower the spinning ring to contact the glass. Keep it centered on your line as you cut fully through the glass. Let water lubricate.

5. Lift and Stop Blade

When cut is complete, lift blade and turn off saw. Remove glass and empty water tray.


  • Cut in multiple gradual passes on thicker glass. Don’t rush through in one pass.
  • If chipping occurs, slow down feed rate and ensure the ring is centered on cut line.
  • For beveled edges, angle blade to cut at 30-45 degrees.

How to Use Glass Nippers

Specialty glass nippers help shape detailed interior cutouts and stained glass pieces. Here’s how to use them properly:

  • Hold nippers at a 45 degree angle against the glass edge.
  • Grip nipper handles to apply slow, even pressure as the jaws come together.
  • Close jaws fully to nibble away only a small shard of glass.
  • Work gradually along an edge or curve in small increments. Don’t nip off large pieces.
  • Use light pressure and smooth strokes for clean breaks. Forceful hacking leads to cracked edges.
  • Curve the line by alternating the direction you face the nipper jaws as you cut.
  • Keep nippers sharpened. Dull teeth require excessive pressure and cause cracking.
  • Lubricate the cutting wheel and oil nipper jaws periodically for smooth operation.
  • For inside curves, work from an access hole outward. For outside curves, work outside in.