Calorie Calculator: How Many Calories Should I Eat?

The short answer is your maintenance level, minus or plus a moderate adjustment. The calculator estimates what your body burns in a day, then moves that figure by a fixed amount in the direction of your goal. Nothing about the size of your goal changes the size of that daily adjustment. It only changes how long the estimate says the journey takes.

Typical adult maintenance sits somewhere between roughly 1,600 and 3,000 calories per day, with smaller and less active adults toward the low end and larger, younger, or more active adults toward the high end. The USDA Dietary Guidelines for Americans, Appendix 2 estimated calorie needs publishes those ranges by age, sex, and activity level, and they are wide on purpose.

That is also why a headline number like 2,000 calories is not a personal target. It is a label-rounding convention chosen so nutrition facts panels have one reference point to express a percent daily value against. It was never a recommendation for you specifically, and treating it as one is the most common way people end up eating far above or far below what their own body actually uses.

Three steps, all of them auditable. Nothing is hidden, and the whole calculation runs in your browser.

Basal metabolic rate is the energy your body uses at complete rest. The calculator estimates it with the Mifflin-St Jeor equation, which takes weight in kilograms, height in centimetres, and age in years, and applies one of two published constants depending on the sex you select.

The equation comes from Mifflin MD, St Jeor ST, et al., A new predictive equation for resting energy expenditure in healthy individuals, Am J Clin Nutr 1990. It is the predictive equation most commonly recommended for healthy adults, and it carries roughly a 10% margin in either direction at the individual level, per Frankenfield D, Roth-Yousey L, Compher C, Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review, J Am Diet Assoc 2005.

BMR only covers resting energy. Total daily energy expenditure adds the calories you burn moving, training, and digesting food, and the calculator approximates that by multiplying your BMR by one of five factors: 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active, and 1.9 for extra active.

That multiplier is the single coarsest part of the whole estimate, which is why the total carries more uncertainty than the resting figure underneath it. If you want to look at the expenditure side on its own, use the TDEE calculator (your total daily burn).

If your goal weight is below your current weight, the calculator subtracts a fixed 500 calories per day, capped at 25% of your total daily energy expenditure so the adjustment can never swallow a quarter of a smaller person's needs. If your goal weight is above your current weight, it adds a fixed 300 calories per day, capped at 15%. If the two weights are within a pound of each other, the target is simply maintenance.

We cap rather than scale the adjustment to the size of the goal on purpose. Scaling the daily gap to an ambitious goal is how tools end up printing intakes that are unsafe for the person reading them, and a bigger gap does not make a bigger deficit more tolerable. The distance to your goal weight affects only the timeline, never the size of the daily adjustment.

One more guard sits on top of all of it. If the adjusted target would fall below the safety floor, the tool shows the floor instead, or shows no target at all, and recalculates the timeline from the deficit that actually survives.

The most common error on this field is picking a level based on intent rather than on the last four weeks of actual behaviour. A desk job plus three gym sessions is lightly to moderately active, not very active, and choosing the higher band inflates every number downstream of it: the maintenance figure, the target, and the timeline all move together.

For a reference point on what counts as meaningful weekly activity, see the CDC Physical Activity Guidelines for Adults. If you are genuinely between two levels, the lower one produces the more conservative estimate.

The 3,500-calories-per-pound figure is the approximate energy density of stored body fat. Used as a planning rule it assumes a body that never adapts: a fixed deficit producing a fixed weekly change, forever. Real bodies do not behave that way.

As body weight falls, so does the energy cost of maintaining and moving it, which means the same intake represents a smaller and smaller deficit over time. Measured weight-change curves flatten over months rather than continuing in a straight line. Hall KD, Sacks G, Chandramohan D, et al., Quantification of the effect of energy imbalance on bodyweight, Lancet 2011 quantifies how far the linear rule drifts from observed outcomes over longer periods.

If you want a model that accounts for that adaptation rather than assuming it away, the NIH Body Weight Planner is a dynamic model built for exactly that. The timeline this tool prints is deliberately the simpler, linear version, which is why it should be read as an order of magnitude and not as a date.

This tool will not display a daily intake target below 1,500 calories for men or 1,200 calories for women. If your goal and your inputs would require going lower, it shows the floor instead, or shows no target at all, and it says so plainly.

The constraint is nutrient adequacy, not willpower. Below roughly that intake it becomes difficult to meet protein, vitamin, and mineral needs from food alone, and the risks that follow (muscle loss, gallbladder problems, micronutrient gaps) are not the kind of thing a web page should be setting you up for. Very-low-calorie approaches do exist in clinical practice. They come with physician supervision and monitoring, which a calculator cannot provide.

A longer timeline is a normal and acceptable answer. If the honest arithmetic says your goal takes many months at a safe rate, that is the answer, and it is a better one than a number you cannot sustain or should not be eating.

If tracking calories or weight feels compulsive or distressing, that is worth raising with a clinician. In the US you can text "NEDA" to 741741 to reach a trained volunteer at Crisis Text Line, any time.

The equation sees five things: sex, age, height, weight, and a self-reported activity band. Everything else that moves your energy needs is invisible to it.

• Body composition. Two people at the same weight with different amounts of lean mass burn different amounts at rest, and the equation cannot tell them apart.
• Thyroid function and other medical conditions, which can shift energy needs meaningfully in either direction.
• Medications, some of which influence appetite, energy expenditure, or both.
• Sleep. Short or fragmented sleep changes appetite signalling and how much spontaneous movement you do the next day.
• Non-exercise activity drift. When intake drops, unconscious movement often drops with it, quietly shrinking the deficit you thought you had.
• Menstrual-cycle water shifts, which can mask real change on the scale for a week or more at a time.
• Self-reported food intake, which is well documented to be under-reported, often substantially, even by people trying hard to be accurate.

Treat the output as a starting point, then adjust it based on two to four weeks of real-world data: what actually happened to your weight, your energy, and your training. Reality is a better input than an equation.

Weight on a scale is muscle, water, glycogen, bone, organs, and fat, all added together. A calorie target moves that total. It does not decide what the change is made of.

Protein intake and resistance training are what shift that composition. The same deficit, run with adequate protein and regular lifting, tends to preserve more lean mass than the same deficit run without them. That is a different question from the calorie number, and usually a more useful one to be asking.

For the population screening view of weight relative to height, see the BMI calculator, with its limitations spelled out. It is worth reading with the caveat attached: BMI does not distinguish muscle from fat, so two people with very different body compositions can land in exactly the same category.

The estimates above are calculated from your height, weight, age, and activity alone. They are not results from any treatment, and no medication is being offered to produce them.

For some people, consistent effort on nutrition, sleep, training, and stress still does not move things. That is a clinical conversation, not a discipline problem. A physician can look at history, labs, medications, and context, and evaluate whether medical options are appropriate for an individual.

If you have addressed the fundamentals and want to discuss medical options, a physician can evaluate whether treatment such as compounded GLP-1 through Protocol MD is appropriate for you. Compounded semaglutide and tirzepatide are prepared by a licensed compounding pharmacy. They are not FDA-approved, and FDA does not review compounded drugs for safety, effectiveness, or quality. They are available only when a licensed physician determines the treatment is appropriate for you. If you want the background first, here is how semaglutide and tirzepatide differ.

When you are ready, you can start the physician-guided assessment.

Protocol MD is a physician-guided peptide therapy practice: performance, longevity, and body composition, evaluated and prescribed by licensed physicians. Body composition is one of several things patients come to us for, alongside recovery, sleep, energy, and cellular health.

If you want the background, read what peptide therapy is and how it is used.