How much electricity does a strand of christmas lights use?

My wife just loves Christmas and shows it by lighting a lot of Christmas lights. She swears that they don't use a lot of electricity so she wants them lit 24/7. How much is it costing me?|||The average strand of Christmas lights pulls about 1 amp, which is roughly the same as a 100 watt light bulb. It's hard to say how much it is costing you without knowing exactly how many lights you have and the exact wattage. But, most people wouldn't leave a light on all day .... just as you probably wouldn't want to leave your Christmas lights on all day. Hope this helps.