Every calculator gives you the same number it would give anyone your height and age. HabitSync watches what your weight actually does, and corrects the estimate with what it finds.
Most weight loss planners are a calculator with a calendar stapled on. You set a goal and a pace, it draws a straight line to a date, and the line never moves no matter what the scale says. HabitSync draws the same line to start. Then every weigh-in you log pulls it toward what is happening, so the date you are planning around is one the data still supports.
Mifflin-St Jeor, Harris-Benedict, Katch-McArdle. HabitSync ships all three, and they will disagree with each other about you. That is the honest state of the science, and it is why a number from any of them is a place to start rather than a fact about your body.
Log your weight, keep a rough eye on what you eat, and the 60 day projection redraws itself around what is really happening. If your weight is not moving the way the formula said it should, the forecast believes the scale. For the generic version before the personal one, here is how long it takes to lose 10, 20, or 50 pounds by the standard math.
The calories side of a forecast runs on one of three things: a target you set, an average of the meals you logged recently, or a plain BMR estimate when there is nothing recent to go on. HabitSync labels which one it used. Logged days age out too, so one heavy week from last month cannot quietly drive your projection forever.
The planning only works because the tracking is quick. A weigh-in is one number and one tap. The trend line smooths out the daily water swings, so you are not reacting to a salty dinner. Calories are optional: log them and the forecast sharpens, skip them and it runs on a target or an estimate and says which. Either way the record is yours, and it exports to CSV on the free plan.
You can log calories, but that is not the point of it. The point is what your weight actually does against what you actually logged. Plenty of people log a rough target and let the scale do the talking.
A calculator runs your height, weight, age and activity through a formula and hands you a number. It is a starting estimate built from population averages, and it has never met you. HabitSync watches what your weight does over time and works out what your body is really doing, so the projection corrects itself as you log. Seeing that number, your daily burn, is part of the paid plan.
A few days gives you a shape. A month gives you something worth planning around. The app tells you which of three sources the calories side is running on, so a projection built on a stale meal log never looks like one built on this week's real eating.
Nothing breaks. Old logged days stop counting toward the calorie average once they age out, so a heavy week from a month ago cannot keep driving your projection forever. Pick it back up and the numbers catch up with you.
No. Weight, calories, sleep, mood, medication and notes are all free, along with streaks, adherence, your 7 and 30 day averages, and the strongest pattern found in your own data. The full correlation analysis and your measured daily burn are the paid plan.