This is the exact reason why I don't believe in calorie calculators.
Even if you did get the same exact answer at each one...you might lose weight at one calorie level...while someone else here at a similar weight may do fine 100 calories above or below each day what YOU need, due to personal genetics.
Basically, figure out what you eat in an average day. Do FitDay for a day-or food journal on paper, whatever works for you. Eat normally. If you had, lets say, 2500 calories...drop it down by about 500. Do that for a week, weigh in, and see what happens. If you drop a pound or so-then great! Keep it up! If not, drop it down another 100 calories a day for a week-weigh in again. See what happens. You have to find the HIGHEST calorie level that you can eat and lose 1/2-2 pounds per week.
Why do I say "highest"? Because as you lose, a smaller body uses less calories per day. Why? Because if you weigh 180 pounds...then a few months later you weigh 160...it takes less effort to move around 160 pounds all day than it did when you were 20 pounds heavier. Your body uses less energy doing the same things.
Basically, when you get to a point where you do not lose after a couple weeks at a calorie level-it is time to drop it down by about 100 a day. You don't want to START low...then have nowhere to go (without starving and eating in an unhealthy manner) when your loss plateaus.