Enter the total number of calories in deficit per day and the total weight loss required to determine the days to lose that weight.

Weight Loss Time Calculator

Enter any 2 values to calculate the missing variable

Diet labels use Calories (kcal). (1 Calorie (food) = 1 kcal = 4.184 kJ)

Note: This calculator provides an educational estimate and is not medical advice. Consult a clinician or registered dietitian, especially if you’re pregnant, under 18, have a medical condition, or have a history of eating disorders.

Weight Loss Time Formula

The following formula is used to calculate the total time required to lose a certain amount of weight at a caloric deficit. 

T = WL * 3500 / CD
  • Where T is the total number of days required to lose the weight
  • WL is the desired weight loss in pounds
  • CD is the calorie deficit per day. Many adults aim for a deficit that supports about 0.5–2 lb (0.2–0.9 kg) per week, but needs vary. Larger deficits may be unsafe without medical supervision.

To calculate the weight loss time, multiply the desired weight loss by 3500, then divide by the average calorie deficit per day. This is a simplified estimate; real-world weight change can vary over time due to factors like metabolism, water balance, and activity.

Calorie Deficit Definition

A calorie deficit is defined as the number of calories below the number of calories your body needs per day to function that you are consuming. To learn more about maintenance calories, visit our calculator.

Weight Loss Time Example

How to calculate weight loss time?

  1. First, determine your desired weight loss.

    For example, let’s say you wish to lose 10 total pounds.

  2. Next, determine your calories deficit.

    Eating 500 Calories (kcal) less than normal may lead to about 1 pound per week for some people, but results vary.

  3. Finally, calculate the weight loss time.

    Calculate the number of days required to lose 10 pounds using the calculator or formula above.

FAQ

What is a healthy calorie deficit for weight loss?

Many adults aim for a calorie deficit that supports about 0.5–2 lb per week (0.2–0.9 kg/week), but what’s appropriate varies by body size, age, activity level, and medical history. Larger deficits (for example, >~1000 kcal/day) may be unsafe without clinician supervision.

How does the weight loss formula work?

The weight loss formula estimates the time needed to lose a specific amount of weight by dividing the total calorie deficit required (total pounds of weight loss times 3500 Calories (kcal) per pound) by the daily calorie deficit. It provides a straightforward estimate for planning.

Can weight loss be predicted accurately using the formula?

This formula provides a simplified estimate. Actual weight loss can vary due to factors like metabolic adaptation, water/glycogen changes, physical activity, and adherence. If you want a more personalized projection, consider using an evidence-based dynamic planning tool (such as one from a major public health or research institution) and discuss goals with a clinician or registered dietitian.

weight loss time calculator
weight loss time formula