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Weight Gain Calculator

Created by Joanna Michałowska, PhD
Reviewed by Dominik Czernia, PhD and Jack Bowater
Based on research by
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals; The American Journal of Clinical Nutrition; February 1990See 1 more source
U.S. Department of Health and Human Services and U.S. Department of Agriculture 2015–2020 Dietary Guidelines for Americans. 8th Edition.;; December 2015
Last updated: Mar 06, 2024

The weight gain calculator helps you to estimate how many calories you need to eat to increase your weight. In the article below, you will find an explanation of how calorie calculator for weight gain works and practical tips on how to gain weight. Interested? Let's answer the question "How many calories do I need to gain weight?"!

Are you currently pregnant and looking for a tool that estimates how much weight you should gain? Be sure to check out our pregnancy weight gain calculator!

Prefer watching over reading? Learn all you need in 90 seconds with this video we made for you:

How to use weight gain calculator

Let's explain how the weight gain calculator works so you can quickly answer the question, "How many calories do I need to gain weight?".

  1. Unit of measurement selection: Determine your preferred units of measurement before entering values. This choice will impact how the calculator interprets your inputs throughout the process. Select your desired units (metric or imperial) for the Weight, Height, and Target weight variables.

  2. Sex selection: Indicate your sex.

  3. Height entry: Input your height, ensuring it falls within the range of 0.5 m (1'64'') to less than 3 m (9'84'').

  4. Weight input: Enter your current weight, ensuring it falls within the range of 15 kg (33 lbs) to 700 kg (1,543 lbs). This range is set to maintain the accuracy and reliability of calculations, as extremely low or high weights can introduce complexities and may not align with standard health guidelines.

  5. Age input: Enter your age in years. Note that this calculator is designed for adults above 18 and under 120 years old.

  6. Activity level: Choose your activity level from little, light, moderate, hard, physical job/intense exercise, or professional athlete.

  7. Target weight: Proceed to set your desired weight goal. Ensure that the target weight falls within the range of at least 20 kg (44 lbs) and doesn't exceed 300 kg (661 lbs).

  8. Weight gain pace: Choose your preferred pace of weight gain, either a normal pace (0.5 kg or 1 lb per week) or a stricter approach (1 kg or 2 lbs per week).

  9. Graph display options: Choose whether you want to display the graph of weight change, calorie intake, or both.

  10. Results: After entering the information above, you will determine how many calories you need to maintain your current weight. Furthermore, the calculator will generate a graph illustrating how your calorie intake should change week by week and how your weight will increase over time.

💾🔒 Note that your input variables will be autosaved for convenience, ensuring they are remembered between visits. Additionally, all entered variables will be locked to prevent recalculation. These features enable you to revisit the graphs below the calculator, tracking how your calorie intake should change week by week and how your weight will increase weekly, all without having to re-enter data.

For example, consider a 28-year-old woman who is 170 cm (5'5'') tall and currently weighs 60 kg (132 lbs). She engages in light exercise 1 to 2 times per week, and her objective is to reach a weight of 65 kg (143 lbs) through a normal, healthy-paced gain of 0.5 kg or 1 lb per week.

According to the calculator, she needs around 1906 calories to maintain her current weight. However, if she aims to reach her target goal, the suggested calorie intake for the first week starts at 2407 kcal/day and gradually increases, reaching 2477 kcal/day by the end of week 10. After the initial week, her estimated weight is expected to be around 60.5 kg (133.4 lbs), ultimately reaching her goal weight of 65 kg (143 lbs) by week 10.

Want to learn about tips on how to gain weight? Then read on to empower yourself with the knowledge needed for a successful weight gain journey.

Risks associated with being underweight

It's well established that too high a body mass index (if you want to learn more about it, the BMI calculator is waiting for you!) is associated with an increased risk of some diseases, including cardiovascular disease and diabetes, but is being underweight dangerous too?

Actually, it is! There are several risks associated with being underweight:

  • Malnutrition;
  • Vitamin deficiencies;
  • Osteoporosis;
  • Decreased immune function;
  • Decreased fertility; and
  • Increased risk for complications from surgery.

How to gain weight?

The answer to this question may seem pretty simple - you need to eat more calories than you burn. But this is easier said than done. If your total daily energy expenditure (TDEE) is high, it might be difficult to consume as many calories as you need. This may be the case if you are, for example, vigorously running, swimming, cycling, or training some other sports.

🙋 Do you want to calculate how many calories are you burning? We created some comprehensive tools: the TDEE Calculator and the calories burned calculator!

Here are some tips to make sure that you are consuming enough micro and macronutrients:

  • Don't skip main meals;
  • Try to include healthy, energy-dense snacks in your meal plan (e.g., nuts; oat bars);
  • Get some extra calories into your meals by adding toppings like seeds, nuts, healthy dressings, etc.;
  • If drinks decrease your appetite, don't consume them with your meal; and
  • Try to estimate how many calories you eat.

How many calories do I need to gain weight?

First of all, you need to consume more calories than your total energy expenditure. TDEE depends on many different factors, including:

  • Basal metabolism, which depends on many factors itself, including: age, sex, height, weight, fat free mass, and fat mass. You can calculate it with the BMR calculator, that uses the Mifflin-St. Jeor equation;
  • The metabolic response to the food eaten, which is the energy needed to ingest and digest food;
  • Physical activity, which can vary every day. After BMR, this is the second-largest component of TDEE; and
  • Physiological state - growth, pregnancy, lactation, etc.

Once you know how many calories you burn every day, you need to add excess calories. It is estimated that you need approximately 7000 kcal to gain 1 kg or 2 lbs in a week. This means that if you will eat an extra 1000 kcal every day, you should gain 1 kg (2 lbs) within a week.

Have you already had a look at the calorie calculator for weight gain? It estimates your individual daily energy expenditure so you'll know how much calories you need per day to gain weight. If not, just give it a try!

Behind the scenes of weight gain calculator

I'm Joanna Michałowska, a dedicated Ph.D. student specializing in nutrition at Poznan University of Medical Sciences, and I'm the mastermind behind the weight gain calculator. With a profound understanding of the intricacies of diet and nutrition, I'm driven by a passion to make this knowledge accessible to a broader audience.

I was inspired to create a weight gain calculator when I noticed a common need for more clarity among patients trying to understand the complexities of weight gain and its associated steps. I decided to develop a calculator that could simplify this process, providing a broad audience with a reliable and easy-to-use tool to determine their weekly calorie intake and approximate weight gain results.

This calculator is especially valuable for individuals seeking personalized insights into their nutritional needs for weight gain. Recognizing its practicality, I promptly found myself suggesting this tool to individuals needing assistance on their weight gain journey.

I put extra care into the quality of the content so that the information and calculations provided are as accurate and reliable as possible. Each tool undergoes a rigorous process, starting with peer review by trained experts and concluding with thorough proofreading by native speakers. To learn more about our standards, please check the Editorial Policies page.

Disclaimers and warnings

We strive to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a dietitian's personalized assessment. All information on this website is for informational purposes only and is not intended as a substitute for medical consultation. If you have health or weight management concerns, always consult your healthcare provider for personalized advice. Particularly, if you are someone with a history of malnutrition or an eating disorder and are considering changes in caloric intake for weight gain, it's crucial to be aware of refeeding syndrome.

Refeeding syndrome is a potentially serious and life-threatening condition that can occur when transitioning from a state of severe undernourishment to a normal or increased caloric intake. If you are struggling with an eating disorder or malnutrition and are seeking to recover and gain weight, it's imperative to consult with a healthcare professional before making significant changes to your diet.


Can being underweight be unhealthy?

Yes, being underweight can bring certain health conditions.
Maintaining a healthy weight is crucial to having a fulfilling life. A few of the problems that could come with being underweight are:

  • Malnutrition;
  • Vitamin deficiency; and
  • Weakened immune system.

So, make sure you consume calories as per your body's needs.

How many calories should I eat in a day to gain weight?

A minimum of 7000 calories are required to increase your body weight by 1 kg. If you want to gain weight, you need to eat at least 500 to 1000 calories more than you normally would eat in a day. At this rate, you would have gained 1 kg by the end of 1 or 2 weeks, depending on your intake. Also, keep in mind that the calories you burn also impact the rate of weight gain. The more calories you burn, the slower you will gain weight.

Can I maintain my current weight without gaining or loosing any weight?

Yes, you can maintain your current weight.

The main thing to keep in mind is maintaining a balance between the calories you consume and the calories you burn. If both numbers are equal, you are more likely to maintain weight.

How fast can I gain weight?

Each body is unique; therefore, we all have a different tendency to gain weight.
A minimum of 7000 calories equals a weight gain of 1 kg. So, if you consume 1000 calories more than your typical consumption, you would have gained 1 kilogram by the end of the week.

Keep in mind that if you have a workout routine, your calorie consumption will need to be much greater as you are burning more energy.

Joanna Michałowska, PhD
Personal details
Activity level
Light exercise 1-2 times/week
Target weight
Weight gain pace
Normal 0.5 kg (1.1 lb) / week
Calories to maintain weight
😋 This is the amount of calories you should eat to maintain your weight. Check the calorie intake graph below to see your recommended daily energy consumption for weight gain.
Display graphs
Calorie intake
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