Things You'll Need
Table saw or power mitre saw with fine-tooth finish blade
Pen or pencil
1 1/2-inch or 2-inch masking tape
Cellular shades are attractive, work easily and are extremely energy efficient. Most stores offer shades custom made to your dimensions; they also offer free cutting service to customers who buy generic in-store shades. To have the shades cut at the store, you need to know the exact measurement of the window where the shade will be installed. If the shades are cut incorrectly and you want to re-cut them, if you want to cut the shades yourself from the beginning, this is not a complicated project to do.
Determine whether the shades will be installed inside or outside the window frame. Measure the desired length of the shade. If installing outside the window frame, the length should be at least two inches wider than the window frame. This allows one inch on each side of the frame for installation clearance. If installing inside the frame, measure the exact width of the inside of the window frame. Subtract one inch, allowing for a 1/2-inch clearance on each side of the shade.
Measure the actual length of the shade. Do not assume the sizes on the package are accurate. Subtract the desired length from the actual length to determine how much you need to cut off. Then divide the amount you need to cut off in half to determine the amount you need to cut off on each side.
Note: You must cut an equal amount off each side, or the shade will not work properly.
Measure from the end the amount needed to cut off. Retract the shade and wrap both ends tightly with the masking tape, covering the point where the shade will be cut. Make sure the ends are square. This keeps the shade from shifting or cutting crooked, and will keep the shade from snagging or fraying.
Carefully re-measure the amount needed to cut off on each side, and mark on the tape.
Using the mitre saw or table saw with mitre guide, carefully cut the shade at a 90-degree angle.
Remove the tape and install the shade.
Get a helper for accurate measurements and to help hold the blinds.
Most cellular bllinds use a nylon or polyester fabric that will cut cleanly. If you notice any fraying in the fabric after cutting, take an old steak knife with a plastic or wooden handle, heat the end of it in a propane torch until it begins to glow red, then gently run the knife along the edge of the fabric. This will actually melt the edge of the fabric sealing any fraying edges. Do a practice section on the fabric you cut off before doing the actual blind.
Always use caution when working with power tools.
You can only cut a shade down to the roller. If you need the shade narrower than that, you'll have to get a smaller shade.