Know the numbers behind the numbers.
Each calculator on FitCalc is built on an established formula. These guides explain where those formulas come from, what they get right, where they fall short, and how to actually use the result.
TDEE Explained: How to Calculate the Calories You Actually Burn
What TDEE means, how the Mifflin–St Jeor equation gets there, and how to use your number without obsessing over it.
Read the guide →BMI Explained: What It Gets Right, What It Misses
Where BMI came from, what it's actually useful for, and when you should look at other measurements instead.
Read the guide →How to Set Your Macros: A Practical Guide
What protein, carbs, and fat each actually do, and how to pick a split that fits your goal and your life.
Read the guide →How to Use Your One-Rep Max to Plan Smarter Training
What 1RM is for, how the Epley formula estimates it, and how to turn that number into an actual training plan.
Read the guide →How Big Should Your Calorie Deficit Be?
The maths behind losing 1kg a week, why bigger deficits usually backfire, and how to pick a rate that's actually sustainable.
Read the guide →Body Fat Percentage: How to Measure It Without a DEXA Scan
The U.S. Navy tape-measure method, how to measure correctly, and how accurate it really is.
Read the guide →How Much Water Should You Actually Drink?
Why "8 glasses a day" is mostly a myth, and a formula that actually accounts for your body, activity, and climate.
Read the guide →