Weight Gain Calculator – The Bulking Calculator

So you’re trying to gain weight? Our weight gain calculator is a bulking calculator and a calorie surplus calculator in one. It estimates how many calories you burn each day, adds a surplus for your lifting experience (10%, or 5% if you’re advanced) or one you choose, and gives you a daily calorie target, your protein, fat and carbs, and a rough date for reaching your goal weight.

How to Use the Bulking Calculator

1. Enter your weight and pick lb or kg. Height then takes feet and inches, or centimeters.
2. Enter your age and select male or female.
3. Choose how active you are, from Sedentary to Extra active. These are the five levels our TDEE calculator uses.
4. Choose your calorie surplus. “Recommended for my experience” adds 10% to your maintenance calories, or 5% if you’re an advanced lifter. You can also pick 5, 10, 15 or 20%, or type your own surplus in calories a day. Not sure? Keep the recommended option, and see how big your surplus should be below.
5. Pick your lifting experience: none yet, beginner, intermediate or advanced.
6. Enter a goal weight if you want a date. You can leave it empty.
7. Pick how many meals you eat a day, from 3 to 6.
8. If you know your body fat percentage, tap “Know your body fat? Add it” and enter it.

Then press Work out my bulking calories.

Understanding Your Bulking Calculator Results

Your results show:

• Daily calories: your maintenance calories plus the surplus. This is the number to eat each day.
• Weekly gain: in kg or lb and as a share of your body weight, next to the guide for your lifting experience. If your surplus would gain faster than that guide, the result tells you.
• Goal date: if you entered a goal weight, the earliest likely date you reach it and about how many weeks that takes.
• Protein, fat and carbs: grams a day and grams per meal.
• How we got your number: your BMR, the calories your body burns at complete rest (BMR calculator); your maintenance calories, the amount that keeps your weight steady at your activity level (TDEE calculator); the surplus; and your daily target.

Protein follows the same rules as our protein calculator. Fat is 30% of your calories, and carbs make up the rest. To move calories between carbs and fat, open our macronutrient calculator, choose “I know my calories”, enter your daily calories, set your goal to “Gain slowly” and pick more carbs or more fat.

How the Weight Gain Calculator Works

Your numbers come from four steps.

1. BMR. The calculator uses the Mifflin-St Jeor equation in the rounded form our TDEE calculator uses: 10 × weight in kg, plus 6.25 × height in cm, minus 5 × age. Men then add 5 and women subtract 161. If you add your body fat percentage, it uses the Katch-McArdle equation instead: 370 + 21.6 × lean body mass in kg, where lean mass is your weight minus your body fat. If you enter pounds, feet and inches, the calculator converts them first (1 lb = 0.4536 kg, 1 inch = 2.54 cm).

2. Maintenance calories (TDEE). For adults 19 and over, the calculator uses the 2023 National Academies equation for energy needs, the same one our TDEE calculator uses. The equation works from your weight, height, age, sex and activity level; your BMR appears in the result for reference. If you add your body fat percentage, or you’re 18, the calculator multiplies your BMR by an activity factor instead: 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active and 1.9 for extra active.

3. Calorie surplus. The recommended surplus is 10% of your maintenance calories, or 5% if you’re an advanced lifter, the low end of each range in the review below. You can also pick 5, 10, 15 or 20%, or enter your own surplus in calories a day. Your daily calories are your maintenance plus that surplus.

4. Time to your goal. The calculator assumes every kilogram you gain takes 7,700 extra calories, whether you enter pounds or kilograms. That’s about 3,490 calories per pound, close to the 3,500 per pound rule of thumb. It multiplies the weight you want to gain by that figure and divides the total by your daily surplus.

Example: a 30-year-old man who weighs 80 kg and stands 180 cm tall is moderately active and lifts at an intermediate level. His BMR is 1,780 calories. His maintenance, from the 2023 equation, is 2,946. The recommended 10% surplus adds 295 calories, for a daily target of 3,241. That gains about 0.27 kg (0.6 lb) a week, 0.34% of his body weight, inside the guide for his experience. Gaining 5 kg at that surplus takes about 131 days, or 19 weeks. His protein is 128 g (1.6 g per kg), fat 108 g and carbs 439 g, which over four meals is 32 g of protein a meal.

Treat the target date as a rough guide. Your body tends to burn a little more when you eat more, and water and stored carbs move the scale from day to day, so real gains rarely follow a straight line. Weigh yourself on the same day each week and adjust from the trend.

How Big Should Your Calorie Surplus Be?

A 2019 review of off-season bodybuilding nutrition (Iraki et al.) recommends eating 10-20% above maintenance if you’re a beginner or intermediate lifter, and 5-10% if you’re advanced.

• Beginners and intermediates: the calculator starts you at 10%. A 15% surplus can land at or above the top of the weekly rate below, and 20% usually goes past it; the result warns you when yours does. Save 20% for when you’re underweight or haven’t gained on a smaller surplus.
• Advanced lifters: choose Advanced as your lifting experience and keep the recommended option, which sets 5%. Pick 10% for the top of the range.

After two or three weeks, compare your weekly weigh-ins with the rates below. If you’re gaining faster, lower the surplus. If the scale hasn’t moved, raise it a little, for example by 100 to 200 calories a day.

How Fast Should You Gain Weight on a Bulk?

The same review sets a weekly target by training experience. Gain faster than this and the extra weight tends to be fat. The table shows the target and what it means for an 80 kg (176 lb) lifter.

Newer lifters can aim for the upper end, because they build muscle fastest. If you’re underweight, a faster rate is reasonable; ask your doctor what pace suits you.

How Much Protein Do You Need When Bulking?

Aim for 1.6 to 2.2 grams of protein per kilogram of body weight a day (about 0.7 to 1 gram per pound). A 2018 meta-analysis of 49 studies (Morton et al.) found that muscle gains from strength training leveled off at about 1.6 g/kg a day on average, and suggested about 2.2 g/kg for people who want to be sure of getting the full benefit. For an 80 kg lifter, that’s 128 to 176 grams a day.

The calculator sets your protein with the same rules as our protein calculator. If you lift and you’re under 65, that’s 1.6 g per kg, the low end of this range. If you don’t lift yet, or you’re 65 or older, it’s 1.2 g per kg. With a BMI of 30 or more, it uses the weight that would give you a BMI of 25 at your height. The protein tile in your result shows the rate and the weight it used.

Why Some People Struggle to Gain Weight

Gaining solid weight can be rather difficult for some people whether it be in the form of fat or muscle. Now, there can be a few different reasons for this but to keep it simple, a fast metabolism, small appetite, and not eating enough are the most common. 

Although, certain health conditions can also be a cause but in this case, we recommend following the guidance of a medical professional rather than trying to self-treat.

But back to the main causes, a fast metabolism simply means you burn through calories from food at a faster rate than someone with a slower metabolism. Your basal metabolic rate (BMR) which is essentially your metabolism; is determined by the number of calories it takes to fuel the body’s most basic functions at rest like blood circulation, temperature regulation, etc.

But as far as a small appetite goes, if you’re typically not hungry throughout the day then upping your meal frequency and eating more calorically dense foods should be the first step, while liquid calories (e.g. Milk, homemade weight gain shakes, healthy oils, fruit juices, etc) are going to be your best friend ultimately. But oftentimes when someone says they have no appetite or a small appetite, they are just not used to eating enough which becomes their norm and they don’t usually give in to the hunger pangs.

Well, this habit of not eating has to change if you plan on gaining weight/bulking up because you can’t eat like a bird and put on size.

But back to talk of appetite, certain lifestyle factors can also be a big cause like stress, stomach problems, medications, lack of activity, eating disorder, other health issues, etc. But again, this is something that needs to be addressed by consulting with a medical professional.

And the information we’ve provided is intended for generally healthy individuals who to the best of their knowledge only need to make a few minor lifestyle adjustments. 

To ensure you maintain a good appetite make sure you’re doing the following… 

• Stay active but don’t overdo it
• Make your meals more enjoyable
• Eat when you’re relaxed
• Set a schedule to eat more frequently
• Go easy on very high-fiber foods
• Practice mindfulness/meditation/seek help

If you’re a very active individual then you’ll have to eat even more than someone who is sedentary, lightly, or even moderately active, to gain weight without spinning your wheels. A lot of people underestimate their daily caloric intake in general, so you want to be especially observant as to factor in your activities.

But a viable solution for many very active individuals who have a hard time packing on the lbs is to cut down on the duration of their activities.

Then when it comes to mealtime, you should look forward to eating which is very important for staying on track in your weight gain journey. Now, we’re not saying to eat pizzas and ice cream every day but don’t be afraid to add some seasonings, sauces, and other options to make your foods more palatable.

As for the third point, it’s best to eat when you’re relaxed and not on the run where distractions and stress can inhibit your meal intake. Designate a few different times throughout the day to sit down and enjoy your food which is a good habit for maintaining a consistent eating schedule.

We also mentioned fiber. Fiber tends to soak up water and fill you up, so meals built on very high-fiber foods can make it harder to eat enough. Meat, dairy and white rice are lower in fiber and easier to eat in bigger amounts. Keep your fiber intake adequate, though, since you still need it for healthy bowel movements. (1)

And practicing some form of meditation is a good natural and effective way to improve how you deal with emotions which are a normal part of everyday life. Sometimes stress, depression, anxiety, etc can take a toll on your appetite so being in a healthy state of mind more consistently will only help. Although, it is also common for these issues to cause the opposite effect (causing weight gain and emotional eating habits) over the long term. (2, 3)

But when severe enough, we recommend talking to a therapist and/or getting some treatment as you don’t want either of these issues to worsen. 

Also try other related calculators:

• Creatine Calculator
• LBM Calculator
• Macronutrient Calculator
• TDEE Calculator
• Carb Cycling Calculator
• Intermittent Fasting Calculator
• Body Fat Calculator
• Weight Loss Percentage
• Protein Calculator
• Calorie Deficit Calculator

Frequently Asked Questions