Measuring for grommet drapes is the most important step because miscalculations can result in drapes that are too short or not full enough for your windows. To ensure that you get it right the first time, take your time and make a drawing that will hold all your measurements. That way, when you go to the fabric store to choose the perfect fabric to complement your room, you'll have the necessary measurements ready to purchase the right amount of fabric to make your grommet drapes. It's always better to buy a little over your exact measurement because you never know when those extra few inches will make all the difference.
Measuring Grommet Drape Length
Install the drapery rod, making sure that the bottom of the S-hooks will hang above the window frame and each end of the curtain rod will extend 4 to 5 inches from the window frame. Draw a large picture of the windows on paper. It doesn't need to be to scale, just large enough to accommodate multiple measurements.
Measure from where you want your grommet drapes to hang (touching the floor or to the bottom of the window frame) to 1/2 inch above the bottom of the S hook to get your finished length. Note this on your drawing.
Add 8 inches for the bottom hem depth and 3 inches for the top hem depth to your finished length. Write this to the side on your drawing and circle it as your total length. If you plan to use more than one grommet drape panel, multiply the total length by the number of panels.
Measuring for Grommet Curtain Width
Measure the inner width of each window beginning at the bottom, then measuring in the middle and finally at the top. Write the widest measurement on the drawing and repeat for any additional windows.
Draw a thick line above the top of the windows to represent your drapery rod. Measure end to end the drapery rod you installed and note this measurement on your drawing above the thick line.
Multiply this width by 1.5, 2 or 2.5, depending on how full you want the grommet drapes to be. Note this measurement above the drapery rod on your drawing and circle it.
Divide the circled width measurement by 48 or 54 (these are the standard drapery fabric widths) and round up to the closest whole number. This tells you how many fabric widths you need to make the grommet drapes. If you haven't chosen your fabric yet, take your drawing to the fabric store and make this final calculation at the store.