TDEE.TECH is a free, evidence-based fitness calculator platform built by developers and nutrition researchers who believe science-backed health research should be accessible to everyone — no paywall, no signup, no personal data collection.
Our Mission
Too many fitness apps hide basic calorie calculations behind subscriptions or harvest your personal data for advertising. Knowing how many calories your body needs is fundamental health literacy. It should be as easy and free as checking the weather.
Every calculator on TDEE.TECH runs entirely inside your browser. Your age, weight, height, and body fat percentage are never transmitted to our servers and are never stored anywhere.
Who Built This
TDEE.TECH was created by a small team of software engineers and fitness enthusiasts with backgrounds in exercise physiology and clinical nutrition research. Our tools are used daily by people in the United States, United Kingdom, Canada, Australia, India, and Germany — from beginners tracking calories for the first time to competitive athletes fine-tuning their nutrition.
We are not a medical organisation. Our calculators are research tools, not prescriptions. We always recommend verifying results with a registered dietitian or qualified healthcare provider before making significant dietary changes.
Scientific Methodology & Citations
Every formula we implement is sourced from published, peer-reviewed clinical literature. We do not use proprietary or unvalidated equations.
The gold-standard BMR formula for non-obese adults. Validated in a 1990 clinical study across 498 subjects. More accurate than the older Harris-Benedict equation for the modern population.
Used when body fat % is provided. Calculates BMR from Lean Body Mass, making it more accurate for athletes and bodybuilders where standard formulas overestimate caloric needs.
Body Mass Index classification uses World Health Organization cut-off values: <18.5 Underweight, 18.5–24.9 Normal, 25–29.9 Overweight, ≥30 Obese.
The Devine formula (1974) is the most widely used ideal body weight reference in clinical practice and is the basis for drug dosing calculations.
Protein recommendations follow International Society of Sports Nutrition (ISSN) position stands. Carbohydrate and fat ratios follow ACSM guidelines for active adults.
Our Commitment to Accuracy
All calculators provide population-level estimates. The Mifflin-St Jeor equation is typically accurate within ±10% for healthy adults. Individual metabolic rates vary due to genetics, hormonal status (thyroid, PCOS, insulin resistance), medications, and degree of metabolic adaptation.
We always recommend using our results as a starting point and adjusting based on 2–4 weeks of real-world tracking. If your weight is not responding as expected, adjust intake by 100–200 kcal and reassess.
Activity Multipliers — Why We Use Harris & Benedict's Factors
The activity multipliers (1.2 → 1.9) applied to BMR were established by Harris & Benedict and refined through subsequent validation studies. They represent population-average energy expenditure increases across activity categories. These are estimates — not precise measurements — and are the industry standard used by every major nutrition platform.
Privacy & Data Transparency
All calculator inputs are processed 100% client-side in your browser using JavaScript. No data is ever sent to our servers. We use Google Analytics 4 for anonymous, aggregated traffic statistics (pages visited, session duration, country-level location) — this data cannot identify you individually.
Contact
Found an error in our calculations, have a feature request, or want to report a bug? Visit our Contact page — we review every message and typically respond within 48 hours on business days.