Calorie Calculator
Calculate the daily calorie intake that matches your goal, from aggressive fat loss through maintenance to a controlled surplus, with each target derived from your own expenditure.
Calorie Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: Daily calorie needs are your Basal Metabolic Rate multiplied by an activity factor, then adjusted for your goal. Because one kilogram of body fat stores roughly 7,700 calories, a deficit of 550 calories per day produces about 0.5 kg of loss per week, and 1,100 per day about 1 kg.
Formula
7,700 kcal is the conventional energy content of one kilogram of adipose tissue, so a 0.5 kg weekly change corresponds to 550 kcal per day.
Worked Example
- Compute BMR. Mifflin-St Jeor gives 10×82 + 6.25×178 − 5×35 + 5 = 1,763 kcal/day.
- Apply activity. 1,762.5 × 1.55 = 2,732 kcal/day maintenance.
- Choose a goal. Losing 0.5 kg per week needs a 550 kcal daily deficit.
- Apply it. 2,732 − 550 = 2,182 kcal/day.
- Check the floor. 2,182 is comfortably above BMR, so the target is sustainable.
Clinical note. The 7,700 kcal per kilogram rule is a linear approximation that holds well over weeks but overstates loss over months, because expenditure falls as body mass falls. Expect the real curve to flatten and recalculate periodically.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Setting an intake target that matches a specific goal
A goal expressed in kilograms per week converts directly into a daily calorie figure, which is far more actionable than a vague instruction to eat less. Split the result into grams with the Macro Calculator.
Avoiding a deficit that is too aggressive
Targets below basal metabolic rate are flagged here for good reason: they accelerate lean tissue loss and are difficult to sustain. Check your body composition with the Body Fat Calculator before choosing the fastest option.
Planning a controlled surplus for muscle gain
A 275 to 550 calorie surplus supports growth while limiting fat accumulation. Pair it with adequate protein from the Protein Calculator and progressive resistance training.
Methodology & Editorial Standards
Basal metabolic rate uses the Mifflin-St Jeor equation, the most accurate of the widely used predictive formulas for contemporary adults. Maintenance applies the standard activity multipliers from 1.2 to 1.9. Goal adjustments convert a weekly rate of weight change into a daily energy differential using the conventional 7,700 kcal per kilogram of adipose tissue. The safety check flags any target falling below basal metabolic rate, and separately below the widely cited general floors of 1,500 kcal for men and 1,200 for women — thresholds below which nutritional adequacy becomes difficult without supervision. This engine implements the published formula exactly as specified in the source literature, with inputs validated for physiological plausibility before evaluation. Values outside the domain of the formula return an em-dash rather than a misleading figure.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Calorie Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How many calories should I eat to lose weight?
Take your maintenance figure and subtract 500 to 1,000 calories per day, which produces roughly 0.5 to 1 kg of loss per week. For this reference subject that means eating around 2,182 rather than 2,732 calories daily.
Is a 1,200 calorie diet safe?
For most adults it is very low, and it is below basal metabolic rate for nearly all men. It can be appropriate for small, sedentary women under supervision, but sustained intake at that level makes nutritional adequacy difficult and tends to cost lean mass.
Why is my calorie target higher than expected?
Because maintenance scales with body mass and activity. A larger or more active body genuinely costs more to run, and setting a target far below that figure usually backfires through hunger and abandonment rather than producing faster loss.
How accurate is the 7,700 calories per kilogram rule?
It is a reasonable linear approximation over a few weeks but overstates loss over months. As weight falls, expenditure falls with it, so the same deficit yields progressively less loss — the reason plateaus are near universal.
Should I eat back exercise calories?
Not if your activity multiplier already accounts for training. Doing so double counts. Only add them back if you calculated at the sedentary level and log workouts separately.
Do calories from different foods count the same?
For energy balance, broadly yes, but not for satiety, muscle retention or health. Protein has a higher thermic effect and preserves lean mass far better, which is why macronutrient composition matters alongside the total.
How long before I see results?
Scale weight responds within one to two weeks, though early changes are mostly water and glycogen. Genuine fat loss becomes clear over three to four weeks, which is the shortest window worth judging a plan on.
Why did my weight loss stop?
A lighter body burns fewer calories, so the original deficit gradually becomes maintenance. Adaptive reductions in spontaneous movement contribute too. Recalculate every 3 to 5 kg of change.
Can I lose weight without counting calories?
Certainly. Portion control, higher protein intake and reduced ultra-processed food often create a deficit without formal tracking. Counting is a measurement tool, not a mechanism.
Does meal timing affect calorie needs?
Total daily intake dominates. Meal timing can help with adherence, hunger management and training performance, but it does not meaningfully change how many calories you need.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest keeping basic physiology running. TDEE adds activity, digestion and all incidental movement, and is typically 20 to 90% higher depending on how active you are.
Are calorie targets different for men and women?
The equation differs by a constant — plus 5 for men and minus 161 for women — but most of the difference in practice comes from body size and composition rather than sex itself.
Is this calorie calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.
Which currency does it use?
Amounts display in US$ accounting format, but the underlying mathematics is currency-agnostic. The result is identical in any currency, so simply read the figures in your own.
Why does a result show an em-dash?
An em-dash indicates the calculation is not defined for the inputs given — typically a division by zero or a value outside the valid domain. We show a dash rather than a misleading number.
How do I report an error?
Email apexconverter.praxiscalc@gmail.com with the tool URL, your exact inputs, the output received and the output you expected. Verified mathematical errors are patched within 72 hours.