Bariatric Surgery Weight Loss Calculator​

Based on the bariatric procedure you undertake you can expect different levels of weight loss between twelve to eighteen months. The following calculator is meant to give you an idea of what to expect using your gender, height, starting weight and surgery type.

Choose the type of surgery, including gastric bypass, gastric sleeve, and gastric balloon, choose your gender and get your estimated weight loss. 

Related: Determine your Bariatric Candidacy with our BMI Calculator

Use the options below to see what your estimated weight loss will be for the various types of surgeries available.

Starting Weight

155 lbs


After 12-18 Months

155 lbs

Estimated Weight Loss

With you're estimated to lose 67 lbs over 12-18 months

You are currently below your ideal body weight and thus not a candidate for surgery.

Ideal Body Weight (IBW) represents the weight a person should be for their height. Excess Body Weight (EBW) is the amount of weight a person is over their IBW.

Get a Free Consultation

Find out if you are eligible for bariatric surgery. For faster answers please call 844-736-3963.

How to Use Our Bariatric Weight Loss Calculator?

Our calculator is based on large, meta studies on weight loss based on surgery types. 

Instructions as follows:

  1. Choose your gender (for the most reliable results, choose the gender that you were born and not as you currently identify).
  2. Indicate your current height
  3. Share your current weight
  4. Make sure that you identify the procedure you wish to undergo

The left graph will show some yellow and some green. EBW = Expected Body Weight and IBW = Ideal Body Weight. The yellow shows how many pounds you would need to lose to hit your ideal body weight.

The right graph will show your expected weight loss after 12-18 months. You will likely not have hit your ideal body weight in that amount of time.

Related: Gastric Sleeve Expected Weight Loss Calculator

Let’s suppose you are a woman and you are 5’7, 230 lbs and you are going to be going through Gastric Bypass Surgery. Your expected weight loss in order to hit your ideal weight (135 lbs) would be 95 lbs. After 12-18 months you are likely to lose approximately 67 lbs which leaves you 29 lbs away from your ideal body weight.

Purpose of the Bariatric Weight Loss Calculator

There are many reasons why we suggest participating in the bariatric weight loss calculator found on our website. Our calculator is to help our patients understand the potential weight loss outcomes that are to be expected if they follow their post-surgery plans.

Our calculator is designed to provide estimates based on various factors including height, weight, and the type of procedure that is going to be performed.

Our calculator aims to achieve:

  • Estimated Weight Loss: The calculator gives an estimate of how much weight a patient should expect to lose after their procedure.
  • Procedure Comparison: Since we provide the option to choose different procedures on our calculator you are able to see which procedure will likely lead to the most amount of weight loss.
  • Motivation: When patients see the possibilities for their weight loss they are more likely to embark on the journey. They will also keep that goal in mind when things get tough so they know what they can achieve.
  • Educational Tool: Our calculator serves as an educational tool for patients to better understand what they can expect for their specific procedure

We hope that our calculator provides you with a solid estimate on how much weight loss is possible based on the specific surgery that you choose.

Bariatric surgery refers to the operative management of obesity that is aimed at achieving weight loss. It is the most effective option for individuals who have yet to achieve satisfactory weight loss with non-surgical methods. Many of them are available, but the common ones are Laparoscopic adjustable gastric banding, Gastric sleeve surgery, Roux-en-Y gastric bypass, and Biliopancreatic diversion with duodenal switch (BPD-DS). 

The question of “which bariatric surgery is the best” may not have a simple answer as all of them have their pros and cons but what is common to all is the proven effectiveness regarding weight loss and reversal of comorbid conditions. The first step is to meet a doctor and determine if you are a candidate for bariatric surgery.

The eligibility criteria for surgical management of obesity include:

  • Body Mass Index 30+
  • Physical problems that result from excess weight with adverse effects on day-to-day activities
  • Failure of other non-surgical treatment modalities with the risk of obesity-associated morbidity and mortality

After confirming that you are eligible for bariatric surgery, the next step is to determine the best bariatric medicine with your healthcare provider. Although general BMI calculators and eligibility criteria are used for all forms of weight loss surgeries, your unique BMI, body fat, and health conditions may favor the choice of one bariatric surgery over another. Your ultimate goal, whether it is reducing the risk of heart disease or achieving a specific weight loss target, can also impact the choice of the surgical procedure.

Here are some questions to consider:

  • Are you seeking a reversible procedure?
  • Is your BMI significantly high?
  • What is your target for excess weight loss?
  • Do you have any pre-existing conditions that might make you a high-risk patient for a specific procedure?

Consider Your Uniques Needs Before Determining Procedure

The concept of the “best bariatric surgery” is contingent upon the unique needs and goals of each patient. It may involve prioritizing the bariatric surgery with the highest weight loss, the lowest rate of complications, or the most affordable bariatric surgery option.

If you are looking for a procedure that will not alter the anatomy of your gastrointestinal tract or a process that is reversible, then laparoscopic adjustable gastric banding will be the best bariatric surgery for you.

For those with a BMI greater than 50 kg/m² and a desire to achieve the maximum weight loss possible, Biliopancreatic diversion with duodenal switch (BPD-DS) may be the most suitable bariatric surgery option. This procedure limits the stomach capacity and also reduces the absorption of nutrients from the intestine. Up to 78% of the excess weight can be lost within 12-18 months. The drawback of this procedure is that it is irreversible, has the highest rate of complications, and is also the most expensive bariatric surgery in most centers.

Patients are often placed on nutritional supplements for life. Therefore, most surgeons prefer it as the last option when others have failed. For obese patients with heartburn due to gastroesophageal reflux disease (GERD) and a BMI greater than 30, gastric bypass surgery may be the best bariatric surgery if you are considering weight loss.

Various studies, considering the patient’s BMI, have shown that Roux-en-Y gastric bypass improves symptoms in those with GERD. The weight loss is substantial, contributing significantly to weight loss goals, only second to what is obtained after BPD-DS. This result is more effective for people with a BMI of 35 or higher.

Our Guide to Choosing the “Right” Surgery

For us, the ideal bariatric surgery requires a minimal alteration of the digestive tract anatomy, satisfactory weight loss, fewer complications, a low mortality rate, optimal improvement/reversal of comorbidities, and an affordable and low failure rate.

Bariatric surgery, similar to a primary bariatric surgical procedure, such as gastric sleeve surgery, offers almost all these benefits. It involves the resection of the stomach to limit food intake, the intestine is left undisturbed, and the complication rate is low while the risk is low.

The estimated weight loss, or the amount of weight the patient loses, is usually about 60% of excess weight, contributing to the percent total weight change provided. Although nutritional supplements may be required after the surgery, it is short-term.

In conclusion, determining the most suitable bariatric surgery for you is a decision best made by your doctor or other healthcare provider. This decision can be reached after a comprehensive evaluation of your clinical status and a consideration of your desired goals.

Get a Free Consultation

Find out if you are eligible for bariatric surgery. For faster answers please call 844-736-3963.