About BurnMath

Free fitness calculators built by an engineer who got tired of bloated diet apps that wanted his email, his phone number, and a 7-day trial just to add 10 + 20.

What we do

BurnMath builds single-purpose, mobile-friendly fitness calculators that work the way the web used to work: open the page, get the answer, close the tab. No signup. No email collection. No app to download. No upsell to "premium." Calculations run entirely in your browser, your numbers never touch our servers.

Why these formulas?

Every calculator on BurnMath uses peer-reviewed equations from the published nutrition science literature. Specifically:

• Mifflin-St Jeor equation for basal metabolic rate, published in the American Journal of Clinical Nutrition in 1990 and shown in independent comparisons (Frankenfield et al., 2005) to be more accurate than the older Harris-Benedict equation for the general population.
• Katch-McArdle equation for users who provide body fat percentage, more accurate for athletic and lean populations because it uses lean body mass directly.
• Standard activity multipliers (1.2 sedentary → 1.9 very active) drawn from FAO/WHO/UN energy expenditure guidelines.
• ~3,500 kcal per pound of body fat for goal-target estimation. (This is a simplification, the true value varies, but it's the standard heuristic used across the field.)

All formulas are documented in plain English on the calculator pages themselves, so you can see exactly what's being computed.

What we don't do

• We don't ask for your email, phone, or any personal information.
• We don't make accounts.
• We don't sell or share data.
• We don't give medical advice. The calculators are educational tools, not a substitute for a registered dietitian or physician.
• We don't promise weight-loss results. Calorie math is a starting point. Real outcomes depend on consistency, sleep, stress, and dozens of other variables.

How we make money

BurnMath is supported by display advertising via Google AdSense. Ads pay the hosting bill and fund the time it takes to build new calculators. We don't take payment from supplement companies, diet brands, or fitness influencers in exchange for endorsements. The methodology is independent.

Roadmap

Built so far:

• TDEE Calculator, total daily energy expenditure

Coming soon:

• BMR Calculator, basal metabolic rate as a standalone tool
• Body Fat Calculator, Navy method + skinfold
• Macro Calculator, adjustable splits for cutting, maintenance, and bulking
• Calorie Deficit Calculator, week-by-week deficit planner
• Ideal Weight, multiple formulas (Devine, Robinson, Miller)
• One Rep Max, strength-training calculator (Brzycki, Epley, Lombardi)

Disclaimers

All information on BurnMath is for educational purposes only and does not constitute medical, nutritional, or fitness advice. Consult a qualified healthcare professional before starting any diet or exercise program, particularly if you have pre-existing health conditions, are pregnant, or are recovering from injury or surgery.

Calculator results are estimates derived from population-average formulas and may not reflect your individual metabolism precisely. Use them as a starting point and adjust based on real-world results over 2-3 weeks.