About MuscleCalc
Free fitness calculators that give you honest numbers, explain where they come from, and show you what to do with them.
Why we built this
Most fitness calculators hand you a single number and stop there. You do not see the formula, you do not know how precise it is, and you are left to work out what to do next. We built MuscleCalc to fix that: every calculator shows its method, gives a range where the science gives a range, and turns the result into something practical, like protein per meal or the plates to load on the bar.
What you will find here
8 calculators today, covering protein, calories, TDEE, macros, BMI, water intake, ideal weight and one-rep max, plus guides that explain the science behind them. We are adding more calculators and articles over time.
How we make our calculators
- We use published, peer-reviewed methods. For example the Mifflin-St Jeor equation for metabolism, International Society of Sports Nutrition guidelines and meta-analyses for protein, and the Epley and Brzycki formulas for strength.
- We name our sources. Calculator pages and articles link to the research they rely on.
- We test the math. Every formula is checked against hand-calculated reference values before it goes live.
- We review our content. Pages show when they were last reviewed, and we update them when the evidence changes.
Our editorial standards
Articles and calculator guides are based on current research in sports nutrition and exercise science, and link to the studies they rely on. We avoid hype and fads, we separate strong evidence from early findings, and we say so when something is uncertain. Advertising never influences what we write or recommend.
We use AI tools to help research and draft our content. Every figure is checked against the sources we cite, and we correct errors as soon as we find them. If you spot one, tell us.
Your privacy
Calculations run in your browser, and the numbers you enter are never sent to us. Tick "Remember on this device" in any calculator and your numbers are saved in your own browser, ready for your next visit. Read more in our privacy policy.
A note on medical advice
Our calculators give estimates for healthy adults. They do not replace advice from a doctor, registered dietitian or other qualified professional, especially if you are pregnant, under 18 or living with a medical condition.
Get in touch
Spotted an error, or have an idea for a calculator? We would like to hear from you. Contact us.