The size of needle should suit the work being sewn, as well as the thickness of thread used. Charts suggesting the correct needle/thread size combination can be found in every sewing machine manual. As with the advice given for needle types, keep it simple. Almost universally, domestic sewing machines use the 705H needle which comes in many sizes (thicknesses). Choose a size of needle to suit the material being sewn. For light material use a size 70 needle. For medium weight material (general purpose sewing) use a size 80 or 90 needle. For heavier material use a size 100 or 110 needle (not recommended on domestic machines). Packets of needles are marked with these Metric sizes and an older, sometimes called “Imperial” equivalent (11, 14, 16, 18 etc.). If you feel the need to sew frequently with thicker needles than size 110, perhaps you should consider an Industrial machine! Don’t expect to sew too many Horse Rugs or Boat Covers before your domestic machine dies on you. Choose thread that comfortably matches the size of the needle eye. This usually results in the right size of thread for the fabric sewn. Usually. Remember …. insert the needle correctly, check the needle frequently for damage (ie. bent or burred) and replace if necessary.