The Ultimate Calorie Calculator for Flexible Dieting


If you follow the most up to date evidence, then you’ll know that calories provide the environment for your goal to take place. Whether you want to lose fat, build muscle, maintain your weight? Calories are king

While calories are king for weight control, Macronutrients control what type of weight you gain or lose and are just as important.

This calculator was designed to be THE most accurate macro and calorie calculator for your goals on the internet..Give the IIFYM Calculator below a spin. (please provide any feedback in the comments section below)

Want to know how to use the IIFYM Calculator?  Click Here For Detailed info

NOTE : If you are using a mobile device, please turn the screen landscape/wide otherwise you will need to scroll across to see all the totals. 


Step 1: Calculate your TDEE

Step 2: Choose your goals.
Fat Loss
Calories/Day 4
Calories/Day 4
Calories/Day 4
Calories/Day 4
How fast do you want to lose fat?
How fast do you want to gain weight?
Step 3: How much of each macronutrient would you like?

Choose your own ratio of macronutrients :
are calculated based on the calories you have remaining after calories from protein and fat have been subtracted from your TDEE.
Step 4: Your Results.
Carbs Protein Fat Fiber Calories
Grams per day

Calories per Meal

Meals per day



How to Use the IIFYM Calculator

Without knowing and consuming the correct amount of calories for your goal, you may as well be taking shots in the dark where your goals are concerned. That’s where this calculator is your hook up..

Of course, calories are not the end all and be all – WHERE those calories come from is also important so that you can determine where your weight gain or loss comes from.

If you want to build muscle? You want the majority of your weight gain to come from lean muscle tissue. If the goal is fat loss, obviously the weight you want to lose is fat while retaining as much lean muscle as possible.

This is where MACRONUTRIENTS come in. These are your proteins, carbs and fats – Your calories are made up of macronutrients.

This iifym calorie calculator takes the guesswork out of how many calories you need for your goal and what those calories consist of (macronutrients)


STEP 1 – Calculate Your TDEE

Your TDEE is your total daily energy expenditure including all of your daily activities – Step 1 is about finding this total out and calculating how many calories you burn in a given day.



The image above is pretty self explanatory and asks standard questions. Enter your gender, your age, height and weight (Use the tabs to the right of these to choose imperial or metric for each. Whichever you are used to using with)

Do you know your body fat %? This question is really only for people who have a very good idea of their bodyfat percentage.

If you have any doubts about what your bodyfat is, just choose “no”. Honestly, most people do not have an accurate idea of their bodyfat percentage and the calculator will still spit out a relatively accurate estimation of your calories.


STEP 1.2 – Your BMR and Your Daily Activity Level (NEAT + NEPA)




As pictured above, after you’ve input your bodyfat % (or not) you’ll get an initial calculation of your BMR – Basal Metabolic Rate. This is the energy (calories) you expend doing absolutely nothing, simply by being alive.

For all intents and purposes, this number is just for your information and isn’t something you should overly concern yourself with. Maybe just a, “Yay, I know how many calories I burn by being alive!”. It can be a fun fact you can annoy people with at parties or something…I dunno.

Anyway, let’s roll on to the next question pictured above..

How do you describe your daily activity? : Depending on how active your everyday life is (Don’t include exercise in this question), it could potentially make a difference to the amount of calories you burn. Be honest and describe yourself accurately for the most accurate result.



By answering this question, the calculator will try to take into account your NEAT (non-exercise activity thermogenesis) and calculate your NEPA (Non-Exercise Physical Activity).

Sick of acronyms yet? Don’t worry, these two are pretty simple. “Neat” refers to your subconcious, involuntary movements over the course of a day (i.e. fidgeting) and “Nepa” refers to energy you expend intentionally, for example, if you were a builder you’d intentionally need to expend more energy than an office worker at a desk all day.

NEAT can be particularly difficult to predict since subconcious movements can vary vastly between individuals and/or vary due to genetics – Which means this information, again is for your own knowledge and education.

Due to NEAT being such a wildcard, it also means that no calculator can truly claim to be 100% accurate (nope, not even this, the most badass calorie calculator online..) so it would be good practice to take this initial figure as starting point rather than an absolute number. Log your progress and adjust your calories up or down if necessary

(Download my free step by step guide to find out how to do this in more detail)


STEP 1.3 – Your Exercise Activity Level + TDEE Calculation





This is the part of the calorie calculator that separates it from the rest of the calculators online.

Not only does this calculator ask for your estimated activity levels, it will also calculate your calories based on the TYPE of exercise you are performing as well as how much time you spend on those activities for the most accurate result.

The reason this is more accurate is because individual exercises have a different MET value.


MET Value of Exercises

MET stands for “Metabolic Equivalent of Task”. Different exercises and intensities have a different MET value. We can use this figure and multiply it by the duration you did the exercise to estimate a calorie expenditure.

Luckily, you don’t have to get your hands dirty with that – the Ultimate IIFYM Calculator is a smart cookie and calculates it all for you. Just enter the amount of times you perform and exercise per week, the duration of each exercise session as well as the intensity.

Just hit the “Calculate Your TDEE” button and done.


STEP 2 – Choose Your Goal

At this point, your TDEE will be calculated in the IIFYM calculator when you press the “calculate your tdee” button – As pictured below, the calculation appears below the button once it has been pressed.

The next step is to choose your goal..





Click on the box that describes the goal you want to achieve and you’ll see the calories required for that goal. You have 4 options :


FAT LOSS : If you click on this box, you’ll be given the option below to choose how fast you’d like to lose fat. You have the choice of 1/2lb per week, 1lb per week or 1.5lb per week. I wouldn’t recommend losing fat more aggressively than that as you increase your risk of muscle loss, especially the leaner you get.

The more aggressive your fat loss, the lower your calories will be. However, if you do want to get even more aggressive, then you would click on the PERSONAL box and enter your own calories.


BULKING : This option is for those who are looking to add muscle mass to their frame. By clicking this button, you’ll have calories added on top of your TDEE to put you in a calorie surplus thus putting you in a better environment for building muscle.

You’ll again have 3 options to choose from relating to how aggressively you want to build muscle. The options are Lean Gains, Standard Bulk and “What abs…? I’m Bulking Bro”. A good starting place is the “standard bulk” option. Being too aggressive with your calorie surplus will not lead to more muscle gain but will lead to increased excess fat storage.

There is a point of diminishing returns. Start with standard bulk which will add 10% to your TDEE calories and monitor from there. If you add too much fat reduce back to “lean gains” calories or if you are not putting on weight, go for the “I’m bulking bro” option.


MAINTAIN : This goal is pretty simple. You just want to maintain your weight or you want to slowly body recomposition (potentially burn fat and build muscle at the same time). No calculations need to be made here. This is the same calorie value as your TDEE.


PERSONAL : If none of the calculations look right to you and you want to go against the calorie calculator (blasphemy!), then click on the “Personal” button. This will allow you to input your own calorie number. Maybe you want to get more aggressive than the fat loss button allows or maybe you want to be more aggressive than the bulking figure allows? Maybe you want something in between? This is the place to do it.


STEP 3 – Breaking Down Your Calories. Macronutrient Ratios

This next section will break down your calories into macronutrients that will make up your calorie number. The breakdown depends on your choices below.




Initially, you’ll see two options. “Choose predefined ratio” and “Choose your own ratio”. I recommend leaving it on the former.


Protein : You have 4 options here.

0.85 grams of protein per lb of your bodyweight : This is ideal if you’re bulking. The higher calories and carbs that come with your goal of building muscle also have an anabolic effect and therefore 0.85 grams of protein per lb is more than enough to support your goal.

1 gram of protein per lbs of bodyweight : This is the bog standard recommendation and can be used for both bulking and fat loss. I like starting here for fat loss because protein has high satiety properties (keeps you fuller for longer) and this can be useful when you’re on a calorie deficit.

1.15 grams of protein per lb of bodyweight : No need to use this option for bulking at all and should only be used if you’re on a very calorie restricted (aggressive) cut. In this case it may help with lean muscle tissue retention.

Custom : input your own amount of grams per lb of your bodyweight. You’d generally not need to use this option as 0.85-1.15 grams of protein per lb tend to fall in line with evidence based practice.


Fats : You have 4 options here

The research on the optimal amount of fats is quite mixed. Choose your total amount of fats based on personal preference (Staying away from the extremes of too low or too high) and what you think will help you to adhere to your diet.

Generally, it’s recommended to have a healthy mix of different types of fats with more coming from monounsaturated fats and polyunsaturated fats, less coming from saturated fats and a very minimal amount coming from trans fats. Omega 3 fatty acids coming from oily fish/supplements have also been shown to carry potential health benefits. (2-3 grams of EPA/DHA from omega 3’s is the general recommendation. You should be able to find this information on the back of your Omega 3 supplement)

As a maximum I personally wouldn’t recommend going higher than 50% of total calories (This high amount would generally be for the “low carb” crowd)

As a minimum, I wouldn’t go any lower than 0.2 grams per lb of bodyweight and if you do, don’t do it for any appreciable length of time. Fat’s are important for the production of hormones and going too low would not be considered healthy.


Carbs : These will automatically be calculated to fill in the remainder of your calories left over.


What about “choose your own ratio of macronutrients”?

The second option at the top of Step 3 allows you to choose your own custom percentages. Click this button and you’ll see three boxes pop up for each macronutrient. Protein, carbs and fats.

Enter your preferred percentage into each box making sure all 3 boxes add up to 100%

This will then base the macronutrient percentage split on your own personal preference. Again, I would recommend staying within the evidence based guidelines and avoiding extremes. Here are some ranges :


Protein : At least 0.75 grams per lb and no higher than 1.25 grams per lb

Carbs : Non essential macronutrient but an important fuel source for the active individual. Choose this number based on how active you are and how many carbs will be helpful for your individual gym/exercise performance.

Fats : No lower than 0.2 grams per lb of bodyweight.

Once you’re finished filling out the relevant fields, click the “GET RESULTS” button to get your final calculation.



In step 4 you get the results of the calorie calculator for your goal.

NOTE : If you are using a mobile device, please turn the screen landscape/wide otherwise you will need to scroll across to see all the totals. 




The top row shows you how many grams of carbs, protein, fats, fiber and calories you should be aiming to eat daily to achieve your goal.

The second row is really helpful if you structure and prepare your meals. Just click on the number of meals that you eat daily (Above the “Meals per day” area at the bottom) and the calculator will automatically tell you how many carbs, fats and protein you should try to eat at each meal.

This can be very helpful in structuring your meals/recipes when your prepare them. Of course, the beauty of IIFYM is that each meal doesn’t have to be so exact as long as you hit your calorie target and macronutrients. There are various strategies and ways to structure the diet to suit your lifestyle but that’s for another post..


Final Note 

Although yes, I do believe this is the most accurate calorie calculator on the internet (I built it with that in mind), there are some things a calculator can’t calculate for such as genetics and the massive variances in individual’s NEAT.

Take this number as a start point rather than an absolute and monitor your progress. If the data you are tracking (such as weight and/or bodypart measurements and/or gym performance) shows that you are progressing towards your goal and you’re progressing visually, then there’s no need to change.

If your progress stalls and you reach a plateau? Simply make the relevant adjustment to your calories up or down until you are moving in the right direction.


If this calculator was helpful, please share it with your friends on FB, Twitter, Instagram or wherever you hang out on the interwebz. I’d love your feedback on the calculator down below in the comments section too so feel free to start a conversation.



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