Watch more Windows & Window Treatments videos: http://www.howcast.com/videos/405615-How-to-Measure-for-Window-Blinds Ordering the wrong size of blinds for your windows can be a costly mistake. Follow these tips and measure twice for accurate dimensions. Step 1: Determine inside or outside Determine if the blinds will be mounted inside or outside the window frame in your home. Step 2: Measure for outside mounted blinds Measure the exact height and width you want your blinds to cover for outside mounted blinds. Step 3: Check with the manufacturer Visit the blind manufacturer's website for any other tips or directions specific to their products. Place your order in the sure knowledge that your blinds will fit your windows. Step 4: Use a steel tape measure Use a tape measure and measure to the nearest eighth of an inch for accuracy. Tip Do not subtract from the width. The manufacturer will take up to a half of an inch off so the blinds will not rub on the frame and will operate properly. Tip If installing on a wall and not the outside of the frame, add four to five inches on each side for horizontal blinds, or one inch to an inch and a half on each side for vertical blinds, to lessen light gaps and increase privacy. Tip For vertical blinds write down the shortest length. Step 5: Measure from top to bottom Measure from top to bottom inside the frame in three places. Round up to the nearest eighth of an inch and write down the longest measurement. Step 6: Measure the depth Measure the depth of the frame to confirm the blinds you have chosen fit in the opening. Step 7: Measure from side to side Measure from the inside of the right frame to the inside of the left frame on the top, middle, and bottom of the window for inside mounted blinds. Round down to the nearest eighth of an inch and record the smallest measurement. Did You Know? The U.S. Consumer Products Safety Commission and the Window Covering Safety Council recalled all blinds that did not have a split tassel design in order to prevent injury to children. Tip Measure everything twice to avoid error.