Weight Gain Calculator

Enter either your ovulation date or last period date with length of menstrual cycle. The calculator will take moments to predict your implantation date and complete window.




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Weight (lb)

Weight you want to gain? (lb)

Daily Activity

Calorie Surplus

Time to reach your weight goal?

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Target Date


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Created By:

Emily Smith
Emily Smith

Emily Smith

Emily holds a Bachelor's degree in Computer Science from a renowned university. She continued her education with specialized courses in mathematics and data analytics.

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Verified By:



Adam holds a Master's degree in Public Health with a focus on reproductive health and epidemiology.Adam has worked closely with healthcare providers and policymakers to develop evidence-based strategies.

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Based on Research By: U.S. Department of Agriculture and U.S. Department of Health and Human Services Dietary Guidelines for Americans, 2020-2025. 9th edition: Chapter 5 - Women Who Are Pregnant or Lactating; December 2020

Note: The product on this page can provide estimations only due to the change in the length of the menstrual cycle. The results can not replace medical advice by a Doctor.

How Many Calories Should I Eat to Gain Weight?

The Weight Gain Calculator provides personalized recommendations based on age, gender, weight, height, activity level, and weight gain goals. You need to eat more calories to gain weight that your body burns.

The reasonable range of calories is from an extra 300–500 calories per day for slow weight gain. For fast gain of weight, this range is from 700–1,000 calories per day to gain weight quickly.

Factors to Gain Weight

Different factors contribute to the weight gain of a person. For both genders, factors influencing weight gain are generally similar, you can calculate the number of calories to eat by our weight gain calculator. For both genders, there may be some variations due to differences in physiology and metabolism. 

The factors contributing to the weight gain for normal, healthy persons

Caloric Intake

You should know how many calories I need to gain weight regularly. Eating more calories and doing exercise is a simple way to gain body mass and weight. For a proper balance of calories consumed and calories taken try out our weight gain calculator.

Dietary Habits

Eating habits and food choices can contribute to gaining weight. A diet high in processed foods, sugary snacks, and unhealthy fats may be a cause of gaining weight quickly. For a healthy life try to apply the calorie calculator to gain weight in 

Physical Activity

The sedimentary lifestyle may be a cause of the quick weight gain. The other factor can be a lack of exercise, which can lead to accumulation of the excessive fats in the body. 


Basal metabolic rate (BMR) and metabolic efficiency can vary in different individuals. The BMR can affect how many calories should i eat to gain weight regularly. Some people may have naturally higher BMR impacting their weight.


Genetic factors play a role in determining body weight and composition. A person may have a history of obesity in the family or a metabolic disorder

Medical Conditions

The medical condition can cause hormone disorders and hence body metabolism. Addressing underlying healthy conditions for managing weight efficiently.


The BMR (Basal metabolic rate) may tend to decrease with the age of the person. So people do gain weight in the lateral part of their age. The weight gain calculator does include age as a major factor in gaining weight. 

Weight Gain Factors Table

Factor Description
Caloric Intake Consuming more calories than needed leads to gain.
Dietary Habits Food choices and portion sizes influence calorie intake.
Physical Activity Sedentary lifestyles reduce calorie expenditure.
Metabolism Varies among individuals, impacting calorie processing.
Genetics Genetic factors influence body composition and weight.
Hormonal Imbalance Hormonal changes affect metabolism and fat storage.
Stress and Emotions Emotional eating may lead to overeating.
Medical Conditions Certain conditions or medications contribute to gain.
Age Metabolic rate decreases with age.
Sleep Patterns Poor sleep quality affects appetite and metabolism.

Risks Associated With Underweight

There are different risks involved in being underweight including

Risk Description
Nutrient Deficiencies Underweight individuals may lack essential nutrients, increasing the risk of deficiencies in vitamins and minerals.
Weakened Immune System Inadequate nutrition can compromise the immune system, making underweight individuals more susceptible to infections.
Osteoporosis and Fractures Low body weight may lead to reduced bone density and increased risk of osteoporosis, fractures, and bone injuries.
Fertility Issues Underweight women may experience irregular menstrual cycles or infertility due to hormonal imbalances.
Delayed Growth and Development Children and adolescents who are underweight may experience delays in physical growth and development milestones.
Muscle Wasting Chronic undernourishment can lead to muscle wasting and weakness, affecting overall strength and mobility.
Fatigue and Weakness Inadequate calorie intake can result in fatigue, weakness, and reduced energy levels, impacting daily activities.
Increased Risk of Malnutrition Prolonged underweight status may increase the risk of severe malnutrition, leading to serious health complications.
Impaired Cognitive Function Insufficient calorie intake can impair cognitive function, affecting memory, concentration, and decision-making.
Compromised Heart Health Severe underweight status may strain the heart and cardiovascular system, increasing the risk of heart problems.


You can figure out how many calories should I eat to gain weight with the weight gain calculator.



How to Gain 5 kg Weight in 1 Month?

A person can gain 5 kg weight in one month by the following 5 steps

  1. Eat 3 to 5 Meals a Day
  2. Weight Training and Exercise
  3. Add Protein Enriched Food
  4. Add Fibrous Carbohydrates 
  5. Drink High-Calorie Shakes

The weight gain calorie calculator guides the personalized recommendations based on age, gender, weight, height, activity level, and weight gain goals.

What Can Cause Weight Gain Faster?

The different causes of fast weight gain are