FitCalcTools provides free, science-based calculators for health, fitness, and personal finance. Every tool on this site uses peer-reviewed formulas and transparent methodology — no black boxes, no guesswork.
Our formulas include: Mifflin-St Jeor and Harris-Benedict equations (BMR/TDEE), U.S. Navy circumference method (body fat), Devine/Robinson/Miller/Hamwi formulas (ideal weight), Widmark formula (blood alcohol content), Epley/Brzycki/Lombardi equations (one-rep max), Karvonen method (heart rate zones), and Naegele's Rule (pregnancy due date). Financial calculators use standard compound interest, amortization, and budget allocation formulas.
We believe useful tools should be fast, clean, and accessible to everyone without requiring an account, a download, or a payment.
Our calculators cover sleep optimization (based on 90-minute sleep cycles), body composition (body fat, ideal weight, BMR), nutrition planning (macronutrient targets), hydration needs, and compound interest projections.
Each calculator includes detailed explanations of the underlying science, FAQs, and structured data for search engines. We aim to be the most accurate and user-friendly calculator site on the web.
The information provided by FitCalcTools is for educational and informational purposes only. All calculator results are mathematical estimates based on published formulas and population averages. They do not constitute professional medical, financial, legal, or nutritional advice.
Health & medical calculators: Results from our health calculators (BMR, TDEE, body fat, macros, calorie deficit, water intake, sleep, heart rate) are estimates that do not account for individual health conditions, medications, or medical history. Do not use these results to self-diagnose or self-treat any condition. Always consult a qualified healthcare professional before making changes to your diet, exercise, or health regimen. Results do not account for conditions such as diabetes, kidney disease, thyroid disorders, or eating disorders. Pregnant or nursing women, minors, and individuals with pre-existing medical conditions must consult a physician before modifying their diet, exercise, or water intake.
Fertility & pregnancy calculators: Our ovulation calculator and pregnancy due date calculator provide estimates based on average cycle data. They should never be used as a method of birth control or as a substitute for clinical fertility evaluation. Consult your OB-GYN, midwife, or fertility specialist for personalized guidance.
Blood alcohol calculator: BAC estimates are approximations only. Actual blood alcohol levels depend on many individual factors including genetics, medications, food intake, liver function, and hydration. This tool must never be used to determine whether you are safe to drive, operate machinery, or perform any activity requiring alertness. When in doubt, do not drive. If you are concerned about alcohol use, contact SAMHSA's National Helpline at 1-800-662-4357.
Fitness calculators: Our 1RM calculator and other fitness tools provide estimates for training programming. Always use proper form, adequate warm-up, and a qualified spotter when lifting heavy weights. Consult a certified fitness professional before beginning any new exercise program, especially if you have pre-existing injuries or health conditions.
Financial calculators: Our compound interest, budget, debt payoff, salary, and rent vs. buy calculators provide mathematical projections that do not account for taxes, fees, inflation, market conditions, or individual financial circumstances. They do not constitute financial, investment, tax, or legal advice. No fiduciary relationship is established by using our tools. FitCalcTools is not your financial advisor, CPA, attorney, or broker. Users are solely responsible for their financial decisions and any resulting gains or losses. Consult a qualified professional before making financial decisions.
Limitation of liability: FitCalcTools, its creators, and contributors shall not be held liable for any decisions, actions, losses, damages, or injuries resulting from the use of or reliance on any calculator or content on this website. Use all tools at your own risk.
Have feedback, questions, or suggestions for new calculators? We'd love to hear from you.
Email: hello@fitcalctools.com