In my tests, I found the cheapest electric blanket to run was the Silentnight Comfort Control Electric Blanket. Using just 70W of energy when it's in use, that equates to running costs of under 2p per hour when it's on full power. However, if you have a double or king-sized bed, then, depending on your usage, the Silentnight Yours & Mine Dual Control Electric Blanket could work out even cheaper to run. This electric blanket allows you to operate both sides of the bed independently, with each side using just 60W of power. If you regularly go to bed before your partner, or vice versa, or one of you likes a boost of heat whilst the other doesn't, then being able to heat only one side of the bed could save you both arguments, and money, as you're not wasting energy heating both sides of the bed unnecessarily.