Straight answers about how Calorie Check calculators work, how accurate they are, and how to use the numbers.
Below are the questions we hear most often about Calorie Check — how our formulas work, how much to trust the numbers, and when to talk to a professional instead of a calculator. Individual calculator pages also carry their own FAQ sections covering tool-specific questions.
They are accurate estimates, not exact measurements. Our BMR, TDEE, deficit and macro calculators use well-established formulas (Mifflin–St Jeor for BMR, standard activity multipliers for TDEE) that are widely used in clinical and sports-nutrition settings and are considered among the more reliable equations available. But any formula built on population averages will be slightly off for any given individual, because real metabolism is affected by genetics, muscle mass, medical conditions, medication and hormones in ways no calculator can measure from a few form fields. Treat every result as a well-informed starting point to test and adjust over two to three weeks, not a lab-verified number.
Because they likely used different formulas. BMR alone can be estimated with Mifflin–St Jeor, the Harris–Benedict equation, or the Katch–McArdle formula (which needs body-fat percentage), and each produces a slightly different figure — usually within about 5–10% of each other for most people. Our calculators state exactly which formula runs behind the result, so you can compare like with like instead of assuming one tool is simply "wrong."
No. Every calculator on this site runs entirely in your browser using JavaScript. Nothing you type — your weight, height, age, or any other field — is transmitted to a server, stored in a database, or linked to your identity in any way. Refreshing the page clears everything. See our Privacy Policy for full detail.
No. Our restaurant-specific calculators are independent tools built from compiled, publicly available nutrition information and are not affiliated with, endorsed by, or sponsored by the restaurant brands they reference. Menus, recipes and portion sizes change, so figures can drift out of date between our review cycles. If you manage a food allergy, a medical condition, or need guaranteed-accurate figures, always check the restaurant's own official nutrition information directly before ordering.
We calculate Basal Metabolic Rate with the Mifflin–St Jeor equation, then multiply it by an activity multiplier ranging from 1.2 (sedentary) to 1.9 (very active) to estimate Total Daily Energy Expenditure — the calories you burn in an average day including movement and exercise. Full formulas, multiplier definitions and worked examples are on our Editorial Methodology page.
A widely used, generally sustainable approach is a deficit of roughly 300–750 calories a day below your TDEE, which tends to produce weight loss of about 0.25–0.75 kg per week for most adults. Our Calorie Deficit Calculator will total this for you based on your own numbers and goal timeframe, and it will flag deficits that fall outside commonly recommended, sustainable ranges. Very large deficits can be harder to sustain and may affect energy, mood and muscle retention, so faster is not automatically better.
BMI is a simple, fast screening tool, not a diagnostic measurement. It uses only height and weight, so it cannot distinguish muscle from fat — a very muscular person can register as "overweight" on the BMI scale despite low body fat, and an older adult with low muscle mass can register as "normal" despite a higher fat percentage. It is useful as a rough population-level indicator, but body composition, waist circumference, and how you actually feel and perform are generally more informative for an individual.
Recalculate whenever an input changes meaningfully: after a weight change of around 4–5 kg, a significant shift in activity level (starting or stopping regular exercise, a new job that changes how much you move), or roughly every couple of months during an active diet phase, since your maintenance calories fall as body weight drops. Outside of that, checking in every 4–6 weeks is a reasonable default.
Our general calculators are built for healthy adults and do not account for pregnancy, breastfeeding, diagnosed medical conditions, disordered eating history, or medications that affect metabolism or appetite. If any of these apply to you, please speak with a doctor, registered dietitian, or other qualified healthcare professional for individual guidance rather than relying on our figures.
No — all nutrition information on this site is published free for anyone to use. We don't require sign-up, payment, or any personal data in exchange for calculator results.
If you couldn't find what you're looking for, visit our Contact page — we read and respond to every message. For a deeper dive into the exact formulas, data sources and review process behind every calculator, see our Editorial Methodology page.
