I am using the exact same converter with out any problem and yes the 300 watts is more than enough for the sewing machine look at your machine it will tell you the wattage of your machine, my daughter in law is using the same converter and a friend bought the exact same on ebay for her singer machine, I presume you are Australian for this type of converter and you are buying your sewing machine from other country! The voltage throught the machine is going from 240 to 120 etc.. which is what you to get. I hope this help don't hesitate to get back to me if you need more help. Good Luck .