IIFYM Calculator - The Worlds Most Accurate Macro CalculatorĀ  - IIFYM

IIFYM Calculator

The IIFYM macro calculator is the first diet tool of its kind. We developed the IIFYM macro calculator to become the most comprehensive and easy to use weight loss calculator for people following the IIFYM diet plan and flexible dieting plan for fat loss. Our IIFYM weight loss calculator will calculate your specific macros based on all the information you enter so please be as accurate as you can be. Once you have your fat loss macros,  you can create a custom diet plan to help you reach your goal weight.

Our IIFYM Macro Calculator takes the guess work out of calculating macros for immediate fat loss.. All you have to do is enter your details, select your goals and retrieve your macro allotment for the day. Our diet calculator is the most accurate macro calculator there is, making tracking macros & IIFYM diet plan very easy.


Calculate Your Total Daily Energy Expenditure



Main Information



Choose Your Formula

Total body weight formula

lean mass formula

Describe your daily activities


Spend most of the day sitting (bank teller, desk job)

Light Activity

Spend a good part of the day on your feet (teacher, salesman)


Spend a good part of the day doing physical activity (waitress, mailman)

Very Active

Spend most of the day doing heavy physical activity (messanger, capenter)

Exercise Output
How intense is your exsercise


I can hold a conversation while working out and do not break a sweat


I am breathing very hard and challenge myself.


Always break a sweat & have an elevated heart rate. I cannot hold a conversation.


Don't talk to me, don't look at me. I'm here for a purpose and I might die today.


Set Your Goal

Now set your weight loss calories, based on your macro calculator numbers.

Now that the IIFYM Macronutrient Calculator has provided your TDEE (Total Daily Energy Expenditure), it is time set the number of weight loss calories you will be consuming while following the IIFYM diet and flexible dieting. In order to lose weight (burn fat), you need to consume fewer calories than your body needs. This is the key to flexible dieting and rapid weight loss. A calorie deficit of 15-20% off of your TDEE is a safe caloric deficit to shoot for to ensure fast fat loss without burning up your lean muscle mass.

To build muscle, on the other hand, you need to consume slightly more calories than your TDEE. 5-10% is a safe caloric surplus from our macronutrient calculator to consume in order to encourage muscle growth without packing on too much unwanted body fat. This is where the IIFYM Calculator shines! It really is the perfect tool for flexible dieting.

Weight Loss
(burn fat)
-15% Suggested
-20% Aggressive
-25% Reckless
(same as TDEE)
Same as TDEE
(Add Muscle)
+5% (cautious)
+10% (text book)
+15% (aggressive)
Enter Your Own Calories
Enter Your Own
Click here to get your macros!