The bottoms of blinds have a function. They add weight to the blinds so that they drop easily when lowered and keep the opened blinds hanging flat. Without that small amount of weight, the blinds might bunch up or hang loose in front of the window. Roll-up blinds have a hem at the bottom that often contains a dowel inside, but not always. Venetian blinds have a heavy bottom that houses all the strings. Cutting the bottoms of the blinds removes that weight. Properly cutting the bottoms requires replacing the weight.
Whether the roller shade has a dowel at the bottom or not, the cutting process remains the same. After resting the open shade on a flat surface, measure four inches past the desired length. Keep the blind from falling apart by placing strips of tape across the blind just above the measurement. When cutting below the tape use sharp scissors. Some roller shades have fabric while others have strings holding small pieces together. If the roller shade has a dowel, set it on the bottom of the blind. Roll the bottom of the blind to the back until it is the desired length and glue the bottom to create a heavy hem.
Venetian blinds have slats of varying sizes with connecting strings. The blinds are made of wood, bamboo or plastic and have a heavy, and thick, bottom for the strings. Shortening Venetian blinds requires removing the bottom and slipping the slats off the strings before replacing the bottom. Pry off the plastic pieces on the bottom of the blinds. There are usually three, and they cover the knot at the bottom of the string. Untie the knots and slip the bottom off the blinds. Remove as many slats as necessary to achieve the desired length. Once the bottom is back on the blinds, tie the knot as close to the bottom as possible and slip the extra string inside before placing the plastic pieces. Do not cut the string. It is possible to add more slats to the blind, if necessary, if the string remains.
Standard blinds have specific widths and not every window follows standard measurements. It is necessary to cut the width if the blind does not fit inside the window. The process for cutting width is different from the process for cutting length. Measure the correct width and mark the measurement all the way down the blind. Cut the blind using a sharp blade and cut the top of the blind using a hacksaw.
Finding blinds for non-standard size windows is difficult because companies will pre-cut blinds for mass production. Locate a shade manufacture or DIY store that offers to cut blinds to size and does not charge for the service. Before purchasing blinds, measure the windows to determine the correct size. Measure the width and height of the window. If the blinds go inside the window, measure the inside of the window frame from side to side and top to bottom. If the blinds sit on top of the window, measure the window frame and add two inches to each measurement.