THE NUMORIX GUIDE
How to use the Weight Loss Calculator
Last reviewed September 14, 2026
What this calculator does
The engine computes pounds to lose as current weight - goal weight and converts that difference to kilograms with 0.
Formula and method
The engine computes pounds to lose as current weight - goal weight and converts that difference to kilograms with 0.453592. It estimates weeks as ceil(pounds to lose / rate) when current weight is higher, and calculates goal-weight BMR with Mifflin-St Jeor using pounds converted to kg and height inches converted to cm. The returned daily deficit is round(rate x 7700 / 7), while the step text separately prints rate x 3500 as a weekly deficit.
Variables and inputs
The form takes current and goal weight in lb, height in inches, age, male/female formula choice, and rate in lb/week. The component also stores an activity value of 1.55, but it renders no activity field and the engine never uses its activityLevel argument. Output is weeks, a calculated daily calorie figure, and goal-weight BMR.
Worked example
For 180 lb current weight, 160 lb goal, 70-inch height, age 30, male, and 1 lb/week, pounds to lose = 20 and weeks = ceil(20 / 1) = 20. The returned calorie figure is round(1 x 7700 / 7) = 1,100 calories/day, and goal-weight BMR is about 1,692 calories/day. The step text also says 3,500 calories/week, so the two deficit descriptions are not internally consistent.
How to interpret the result
The 20-week result is a straight-line projection from the entered rate, not a promise that scale weight will fall evenly. The BMR output is recalculated at the goal weight, but it is not a maintenance calorie target and is not multiplied by activity in this engine.
Common mistakes to avoid
Enter the rate in pounds per week, not kilograms per week or a daily percentage. Check that goal weight is lower than current weight; otherwise the engine returns zero weeks even though it does not present a separate maintenance or weight-gain mode. Do not rely on the activity value because it is not used.
Assumptions and limitations
The implementation contains a meaningful inconsistency: its returned daily deficit uses 7,700 calories per kilogram while rate is labeled lb/week, and its explanatory step uses 3,500 calories per pound per week. The local totalCalories variable is unused, activityLevel is ignored, and the projection omits water shifts, adherence, adaptive metabolism, medications, health conditions, and lean-mass change. Treat the output as educational arithmetic and obtain individualized weight-management advice when needed.