The Calorie Calculator estimates how many calories a person needs each day to maintain current weight, then offers a moderate deficit or surplus as optional adjustments. Enter age, sex, height, weight and activity level; the tool returns a maintenance figure first, with any planned change capped at 500 calories either side of that baseline.
Daily energy need is an estimate, not a prescription. Bodies differ in muscle, hormones and habit, so two people with the same inputs can burn different amounts. This page returns the number, shows how it was built, and states the floors and limits that keep the result usable as general information rather than medical advice.
Calculate your daily calorie needs
Maintenance calories are the energy intake that roughly balances what the body uses across a normal day. That total is often called TDEE (total daily energy expenditure): basal metabolism plus the cost of movement, digestion and daily living. The calculator estimates it from resting burn and an activity multiplier drawn from a standard table.
Enter age, sex, height and weight so a BMR can be computed, then pick the activity level that best matches a typical week. The result opens on the maintenance figure. A moderate deficit or surplus of up to 500 calories per day is available as a secondary choice, never as the default view.
The figure is a planning estimate for general information. It does not diagnose a metabolic issue, and it does not replace advice from a doctor or dietitian for anyone with a medical condition, a history of disordered eating, or a need for supervised intake change.
Understand maintenance, deficit and surplus
Energy balance is simple in outline and uneven in practice. Eat roughly what is burned and weight tends to hold. Eat less and weight tends to fall over time. Eat more and weight tends to rise. Maintenance is the neutral reference this tool shows first, because it is the baseline every other plan is measured against.
A moderate deficit of about 500 calories per day is the largest reduction offered as a preset. Using the common convention of roughly 7,700 calories per kilogram of body fat, that pace corresponds to about half a kilogram per week on average. Results vary; water, glycogen and training all move the scale from week to week.
A moderate surplus of the same size supports gradual gain for those building muscle or recovering from under-fueling. Deficit and surplus sit with equal weight in the interface. Neither is framed as the goal everyone should chase. The right direction depends on the person, the context and clinical guidance when needed.
Choose a BMR formula
Basal metabolic rate is the calories used at complete rest. The Calorie Calculator multiplies that resting figure by an activity factor to reach daily maintenance. Three common equations are available; Mifflin-St Jeor is the default for the general adult population.
Mifflin-St Jeor (default): `` Male: BMR = 10×kg + 6.25×cm - 5×age + 5 Female: BMR = 10×kg + 6.25×cm - 5×age - 161 `` Source: Mifflin MD, St Jeor ST, et al., 1990.
Harris-Benedict (revised): Roza and Shizgal's 1984 revision of the 1919 Harris-Benedict equations. Slightly different coefficients; useful as a second opinion when comparing estimates.
Katch-McArdle: 370 + 21.6 × lean body mass (kg). Needs a body-fat estimate. Often better for lean, muscular adults because it keys off lean mass rather than total weight.
Activity multipliers applied to BMR:
| Activity level | Factor |
|---|---|
| Sedentary - little or no exercise | 1.2 |
| Light - exercise 1 to 3 times/week | 1.375 |
| Moderate - exercise 4 to 5 times/week | 1.465 |
| Active - daily exercise or intense 3 to 4 times/week | 1.55 |
| Very active - intense exercise 6 to 7 times/week | 1.725 |
| Extra active - intense daily or physical job | 1.9 |
Pick the row that matches a typical week, not the most optimistic week of the month. Overstating activity is the usual way people under-estimate how much they already eat relative to burn.
Calculate calories for a moderately active adult
A worked profile makes the maintenance path concrete: resting burn first, then the activity row, then optional offsets. The numbers below use Mifflin-St Jeor and the moderate multiplier 1.465 so every step can be checked by hand against the reference table.
Take a 35-year-old woman weighing 70 kg at 165 cm who exercises about four times a week. Mifflin-St Jeor is the default formula for this walkthrough.
1. Compute BMR. `` BMR = 10×70 + 6.25×165 - 5×35 - 161 = 700 + 1031.25 - 175 - 161 = 1,395 kcal/day ``
2. Apply the activity multiplier. `` Maintenance (TDEE) = 1,395 × 1.465 ≈ 2,044 kcal/day ``
So about 2,040 calories per day is the maintenance estimate for this profile. A moderate deficit preset would show about 1,544 kcal/day (2,044 - 500). A moderate surplus would show about 2,544 kcal/day.
That deficit stays above the 1,200 kcal floor used for female profiles in this tool, so the figure can appear as a planned intake with the usual estimate disclaimer. If maintenance minus 500 had fallen below the floor, the tool would still show the arithmetic but would flag professional guidance and would not present the low number as a target.
The same person on a sedentary day (factor 1.2) would land near 1,674 kcal maintenance. Activity choice moves the result by hundreds of calories; honesty about weekly movement matters more than fine-tuning the last digit of BMR.
Set a safe, moderate deficit
When weight loss is the chosen direction, this page supports only a moderate step: about 500 calories below maintenance. That is the largest deficit preset in the engine. Larger cuts are not offered, because unsupervised very-low intakes carry real risk and belong under medical care when they are used at all.
Half a kilogram per week is a rough average expectation from a 500-calorie daily gap, using the 7,700 kcal per kg convention. Some weeks the scale will move more; some weeks less. Strength training, higher protein within a sound overall diet, and sleep all affect how the body partitions the loss between fat and lean tissue, which no calorie equation can predict from age and height alone.
Gradual change is easier to sustain and easier to reverse if circumstances shift. Anyone with a medical condition, pregnancy, a history of disordered eating, or unexplained weight change should speak with a clinician before changing intake. The calculator does not construct very low calorie diets and does not explain how to build one.
Understand calorie floors
Below certain unsupervised intakes, this tool stops treating the number as a normal planning target. The floors used here are about 1,500 kcal per day for male profiles and about 1,200 kcal per day for female profiles. They reflect commonly cited minimums for unsupervised dieting; they are not personalised medical figures.
When maintenance minus 500 lands below the relevant floor, the result block shows a visible note recommending professional guidance. The computed intake may still appear for transparency, but it is labelled as a computed figure, not as a target to chase. No preset is allowed to push further below maintenance than 500 calories.
Very low intakes are used only under medical supervision when they are used at all. This page does not provide a pathway to build one. If the floor warning appears, the useful next step is a conversation with a doctor or registered dietitian, not a tighter deficit in another app.
Understand what a calorie estimate can and cannot tell you
A maintenance estimate answers one question: roughly how much energy this profile burns on a typical day, given the formula and activity row chosen. It does not measure thyroid function, insulin response, medication effects, or the gap between reported and actual intake.
Individual metabolism varies. Two adults with matching inputs can differ by a few hundred calories. Wearable devices estimate expenditure with their own error bands. Food labels and kitchen scales also carry rounding. Treat the result as a starting range to observe against real weeks of eating and weighing, then adjust.
The Calorie Calculator provides an estimate for general information. It is not medical advice. It cannot clear someone for a diet, diagnose why weight is stuck, or replace clinical care. Read the maintenance number as a reference line. Pair any planned deficit or surplus with attention to how energy, mood and training feel over time, and with professional input when health history calls for it.
Frequently asked questions
What is TDEE?
TDEE means total daily energy expenditure: the calories used across a full day, including rest, digestion and activity. The calculator estimates TDEE by multiplying a BMR by an activity factor. That product is the maintenance figure shown first on this page.
How accurate is a calorie calculator?
Population equations such as Mifflin-St Jeor are reasonably accurate on average and can miss by several percent for any one person. Activity self-rating is usually the larger error. Use the estimate as a starting point and adjust from weekly trends rather than treating a single number as exact.
Should maintenance calories be the starting point?
Yes for planning. Maintenance is the neutral reference; deficit and surplus are optional offsets from it. Starting from maintenance makes it clearer how large a change really is, and it avoids treating weight loss as the default goal for every visitor.
How large a deficit does this tool allow?
The largest deficit preset is 500 calories per day below maintenance. The engine does not return a larger planned cut. That cap exists so the tool stays within a moderate, unsupervised planning range.
What are the calorie floors?
About 1,500 kcal per day for male profiles and about 1,200 kcal per day for female profiles. If a moderate deficit would land below the floor, the tool shows a professional-guidance note and does not present the low figure as a target.
Does a surplus work the same way as a deficit?
Yes in structure: the surplus preset adds up to 500 calories above maintenance. It is offered with the same weight as the deficit option for those aiming to gain gradually. Individual results still vary with training and protein intake.
Which activity level should I pick?
Choose the level that matches a typical week, including job movement and training. If unsure, start one step lower rather than higher; overestimating activity underestimates how much is already being eaten relative to burn.
Can this replace a dietitian?
No. The estimate is general information. Anyone managing illness, medications that affect weight, pregnancy, breastfeeding, adolescence, or a history of disordered eating needs individual guidance from a qualified professional.
Why does my watch show a different burn?
Wearables use heart rate, motion and proprietary models; equation-based TDEE uses age, size and a coarse activity row. Both are estimates. Prefer multi-week weight and intake trends over any single device number when deciding whether to adjust.
Summary
The Calorie Calculator estimates daily maintenance calories from a BMR equation and an activity multiplier, then optionally applies a moderate deficit or surplus capped at 500 calories. Maintenance appears first.
Floors near 1,500 kcal (male) and 1,200 kcal (female) trigger a guidance note when a planned intake would fall below them, and the low figure is not presented as a target.
Mifflin-St Jeor is the default resting formula; Harris-Benedict and Katch-McArdle are alternatives. The result is an estimate for general information, not medical advice, and it cannot capture every factor that shapes an individual metabolism.