Following the Atkins eating plan you shouldn't have to count calories. But for those of us who watch them, the rule is 10 to 12 times range. This range has to rules people argue between. I follow the time your current weight rule. Other belieave it time you goal weight. I guess then a good rule of thumb would be dont go below 10 to 12x your goal weight, and not above 10 to 12x your current weight. Find what ever range your are comfortable in within that area.