Measuring for Eyelet Curtains. We recommend that you fix your pole at least 10cm (4) above the window. This should be done before taking measurements. We recommend you use a metal tape measure, which will not stretch.f you prefer a fuller look to your curtain then simply add 20-30cm to the size calculated. 1  Measure the width of the window. 2  Add 30cm to this measurement. 3  You now have the required curtain width (same width as the pole). 4  Enter this width in the 'Width' box after selecting your fabric.