What This Calculator Does
The Time to Reach Goal Weight Calculator estimates how long it will take to reach a target weight given a consistent daily calorie deficit. It is built on the widely used rule of thumb that one pound of body fat is roughly equivalent to 3,500 calories. By dividing the total calorie gap to your goal by how many calories you cut each week, the tool gives a simple weeks-and-days projection.
How to Use It
Enter your current weight and goal weight in pounds, then enter the average daily calorie deficit you plan to maintain (the gap between calories burned and calories eaten). The calculator returns the estimated number of weeks and days to reach your goal, the total weight to lose, and your expected weekly loss.
The Formula
The core equation is:
$$\text{Weeks} = \frac{\left(\text{Current (lb)} - \text{Goal (lb)}\right) \times 3500}{\text{Daily Deficit} \times 7}$$The numerator is the total calorie deficit needed to lose all the target pounds (each pound \(\approx\) 3,500 calories). The denominator is your weekly deficit. A 500 cal/day deficit equals 3,500 cal/week, or about 1 pound per week.
Worked Example
Suppose you weigh 180 lb and want to reach 160 lb with a 500 cal/day deficit. You need to lose 20 lb, or
$$20 \times 3{,}500 = 70{,}000 \text{ calories}$$Your weekly deficit is
$$500 \times 7 = 3{,}500 \text{ calories}$$So
$$70{,}000 \div 3{,}500 = 20 \text{ weeks (140 days)}$$losing about 1 lb per week.
FAQ
Is the 3,500-calorie rule exact? No. It is a useful approximation; real weight loss slows as metabolism adapts, so treat the result as a planning estimate.
What is a safe deficit? Many guidelines suggest 500–1,000 cal/day for steady loss of 1–2 lb per week. Consult a professional for personal advice.
Can I use kilograms? This version uses pounds and the 3,500 cal/lb figure. Convert kg to lb (1 kg \(\approx\) 2.205 lb) before entering values.
