Calorie Calculator

What this calculator gives you

A calorie calculator answers one question: how much should you eat each day to move your weight in the direction you picked? It answers in three steps. First it estimates the energy your body burns while resting. Then it adds the energy your daily movement costs. Then it puts a gap between that total and the food you eat, and the size of the gap sets how fast the scale moves.

Three terms cover the whole page. Basal metabolic rate, or BMR, is the energy you would burn lying still all day. Total daily energy expenditure, or TDEE, is BMR multiplied by an activity factor. Your calorie target is TDEE plus or minus the daily gap that matches your goal. The calculator shows all three, so you can see which piece moved when a number surprises you.

The results table goes past the headline figure. It also returns body mass index, protein, fat and carbohydrate grams, a fiber target, calories for each meal, and a date when you would reach a goal weight at the pace you chose. Those extra lines exist because a calorie number on its own does not tell you what to put on the plate.

What the tool cannot do is measure you. Two people with the same age, height and weight can burn a few hundred calories a day apart, because muscle mass, medication, sleep and thyroid function all sit outside any equation. Treat the first number as a starting bid. The scale over two to three weeks is the referee, and the section on mistakes below explains how to read it.

Why the number deserves attention at all: the CDC reported that 41.9 percent of U.S. adults had obesity in 2017 through March 2020, with severe obesity at 9.2 percent (CDC Adult Obesity Facts, page updated 2024). A daily target you can hold for months beats a perfect plan you abandon in ten days.

The formula behind the number

Resting burn comes from the Mifflin-St Jeor equation, published in 1990 in the American Journal of Clinical Nutrition. The authors built it from 498 healthy adults aged 19 to 78, including 234 people with obesity, and measured resting energy by indirect calorimetry (PubMed record for Mifflin et al., 1990).

For men, BMR = 10 x weight in kilograms + 6.25 x height in centimeters - 5 x age + 5. For women, the same expression ends with -161 instead of +5. Pounds become kilograms by multiplying by 0.45359237. Inches become centimeters by multiplying by 2.54.

Here is the whole calculation for the default case, a 35 year old man at 5 feet 10 inches and 180 pounds. His weight is 180 x 0.45359237 = 81.6 kg. His height is 70 x 2.54 = 177.8 cm. The weight term is 10 x 81.6 = 816. The height term is 6.25 x 177.8 = 1,111. The age term is 5 x 35 = 175. Add the three and the sign flips once: 816 + 1,111 - 175 + 5 = 1,757. The widget prints 1,758 because it keeps the decimals until the last step.

Resting burn is not what you eat. The multiplier below turns BMR into TDEE, and it is the shakiest input on the page because it depends on a self report. Pick the row you could defend to a friend who has seen your week.

Those multipliers are a working convention, not part of the 1990 paper. They also do not travel well. The NIDDK Body Weight Planner uses its own scale that runs from 1.4 for sedentary to 2.5 for very active, and it sets 1.6 as a default for someone who sits at work and walks or cycles once a week. A 1.55 on this page and a 1.55 in that planner are not the same quantity, so do not copy a number between tools.

The last step is the gap. A pound of body fat stores about 3,500 calories, which is the figure NIDDK uses in its weight management teaching material (NIDDK weight management teaching material). Divide 3,500 by seven and 500 calories a day is the arithmetic behind a pound a week. Half a pound a week is 250 a day, 1.5 pounds is 750, and 2 pounds is 1,000.

How to use it, step by step

Six steps, about five minutes, and one of them happens three weeks later.

1. Weigh yourself the same way twice. Step on the scale in the morning, after the bathroom, before food, three days running, and average the three. A single reading swings by two or three pounds on water alone. The average is the number you type.

2. Measure height without shoes. Most people round up by an inch. An inch of height moves BMR by about 16 calories, which is small, but the same rounding habit applied to weight moves it by 45 calories per 10 pounds.

3. Choose the activity row honestly. If you train hard four days a week and sit the other three, moderate is right. Gym sessions do not cancel a nine hour desk day.

4. Pick a pace you can hold. One pound a week suits most people. Two pounds a week is where the arithmetic starts fighting the floor, as the next section shows.

5. Add a goal weight if you want a date. The field is optional. Leave it at zero and the tool skips the timeline.

6. Check the scale after two to three weeks. If the average dropped faster than planned, add 100 to 200 calories. If it did not move at all, cut 100 to 200. Small corrections beat a restart.

One reading habit matters more than any setting. The FDA notes that 2,000 calories a day is a general guide for nutrition advice and that your needs depend on age, sex, height, weight and activity, and it also points out that serving sizes on labels describe what people typically eat, not a recommended portion (FDA, Calories on the Nutrition Facts Label). A bag of chips with three servings is three times the label. Weigh food for a week when you start, and you will find the 300 calorie error that no formula can fix.

Three worked examples

Same equation, three bodies, all numbers taken from the calculator output.

Example A: 35 year old man, 5 feet 10 inches, 180 pounds, moderate activity, wants to lose 1 pound a week. Resting burn 1,758 calories, daily burn 2,724, target 2,224. That is a 500 calorie gap, so the projection is 1.00 pound a week and ten weeks to reach 170 pounds. Protein at 1.6 grams per kilogram is 131 grams, or 523 calories. Fat at 30 percent of the target is 74 grams, or 667 calories. Carbohydrate takes what is left: 1,034 calories, or 259 grams. Fiber lands at 31 grams, and the day splits into 556 calories at breakfast, 667 at lunch, 779 at dinner and 222 in snacks. His BMI is 25.8, which the table labels overweight.

Example B: 35 year old woman, 5 feet 6 inches, 170 pounds, moderate activity, wants to lose 1 pound a week. Resting burn 1,483, daily burn 2,298, target 1,798. Protein 123 grams (494 calories), fat 60 grams (540 calories), carbohydrate 191 grams (765 calories), fiber 25 grams. Twenty pounds to her 150 pound goal takes 20 weeks at this pace. Her BMI is 27.4.

Example C: 30 year old man, 5 feet 10 inches, 260 pounds, light activity, wants to lose 1.5 pounds a week. Resting burn 2,146, daily burn 2,950, target 2,200. The gap is 750 calories, so the pace holds at 1.50 pounds a week and 40 pounds takes 27 weeks. Protein 189 grams (755 calories), fat 73 grams (660 calories), carbohydrate 196 grams (785 calories), fiber 31 grams. BMI 37.3.

Read the three side by side and one pattern shows up. The bigger body carries the bigger target even while losing faster, because resting burn scales with weight. Example C eats 2,200 calories to lose a pound and a half a week. Example B eats 1,798 to lose one. The woman in example B is working with a smaller budget and a slower pace, which is why a 1,200 calorie floor appears in her range and not in his.

For contrast, the same 35 year old man from example A who only wants to hold 180 pounds eats 2,724 calories. Maintenance is the number to know even when the goal is loss, because every diet ends there.

When the math hits a floor

Subtract 1,000 calories from a small body and the answer stops making sense. Take a 60 year old woman at 5 feet 2 inches and 140 pounds, light activity, who asks for 2 pounds a week. Her resting burn is 1,158 calories and her daily burn is 1,593. A 1,000 calorie gap would put her at 593 calories a day.

The widget refuses that answer. It holds the target at 1,200 calories and reports the real gap: 393 calories, which is 0.79 pounds a week, not 2. Her macros at that target are 102 grams of protein (406 calories), 40 grams of fat (360 calories) and 108 grams of carbohydrate (434 calories). Ten pounds takes 13 weeks instead of five.

The floor is not a website rule. The 2013 AHA/ACC/TOS guideline for managing overweight and obesity in adults describes an energy intake target usually set at 1,200 to 1,500 calories a day for women and 1,500 to 1,800 for men, adjusted for body weight and activity, with a deficit of 500 to 750 calories a day (JACC, 2013 guideline). The same guideline sets a first goal of 5 to 10 percent of body weight over about six months. The NHLBI puts the same target in patient language and notes that a 3 to 5 percent loss already improves triglycerides and blood glucose (NHLBI, Aim for a Healthy Weight).

The CDC's own guidance is a pace, not a floor: people who lose about 1 to 2 pounds a week are more likely to keep it off than people who lose faster (CDC, Steps for Losing Weight, updated January 2025).

Two groups should not use this page as written. The NIDDK planner is built for adults 18 and older who are not pregnant or breastfeeding, and its disclaimer says so. Pregnancy, breastfeeding, a history of eating disorders, diabetes medication, thyroid treatment or any condition that changes appetite belongs in a conversation with a clinician, not in a web form.

Splitting the calories into protein, fat and carbs

A calorie target without a macro split turns into guesswork at dinner. The split here has one guideline anchor and two deliberate choices, and the page says which is which.

Protein is the anchored piece. The Dietary Guidelines for Americans 2025-2030, released in January 2026, sets protein serving goals at 1.2 to 1.6 grams per kilogram of body weight per day, adjusted for calorie needs (Dietary Guidelines for Americans 2025-2030). That is a range, not a single number, so the calculator offers 1.2, 1.4 and 1.6 and defaults to the top of the range for people who are cutting. For the 180 pound man that is 131 grams. For the 140 pound woman it is 102 grams.

Fat is a design choice. The tool spends 30 percent of the target on fat. That is mid range for a mixed diet and it keeps the arithmetic easy: 30 percent of 2,224 is 667 calories, and 667 divided by 9 is 74 grams. The guideline number that does carry authority is the ceiling on saturated fat, which the same 2025-2030 edition puts at no more than 10 percent of total daily calories.

Carbohydrate is the remainder. Whatever calories are left after protein and fat go to carbohydrate: 2,224 minus 523 minus 667 leaves 1,034 calories, and 1,034 divided by 4 is 259 grams. Protein and carbohydrate carry 4 calories per gram and fat carries 9, the factors the FDA uses on the Nutrition Facts label. Fiber follows the 14 grams per 1,000 calories rule that NIDDK cites from the Dietary Guidelines, so 2,224 calories comes to 31 grams.

Two more numbers come from the same 2025-2030 edition: sodium under 2,300 milligrams a day for people 14 and older, and no more than 10 grams of added sugars in any single meal. Both are easy to blow through at breakfast, which is why the meal split matters. Breakfast takes 25 percent of the target, lunch 30, dinner 35 and snacks 10. For the 180 pound man that is 556, 667, 779 and 222 calories.

Five mistakes that break the math

1. Eating back exercise calories twice. The activity multiplier already pays for your training. Log a 400 calorie run, add 400 calories to the target, and the deficit disappears. Pick one accounting method: either a moderate multiplier and no exercise credits, or a sedentary multiplier and honest credits.

2. Believing the multiplier more than the scale. NIDDK warns on its own planner that people often underestimate how much they eat, and that its values will run high for someone with a low metabolism or a fully sedentary week. The same warning applies here. Three weeks of flat scale weight outvotes any multiplier.

3. Reading one morning's weight. Water, sodium, glycogen and the previous night's dinner move the scale by two or three pounds. A 500 calorie daily deficit removes about one pound of fat a week, and a single salty meal can hide it. Compare seven day averages, not Mondays.

4. Treating 3,500 calories per pound as a law. It is a useful shortcut for a few weeks, not a forecast for a year. As body weight falls, resting burn falls with it, so a fixed 500 calorie gap produces slower and slower losses. A published review of obesity myths points out that a set daily deficit cannot keep producing the same weekly loss indefinitely (a 2023 review of obesity myths in NIH's PubMed Central). Recalculate at each new weight: ten pounds off cuts resting burn by roughly 45 calories a day, which turns a 1.00 pound week into about 0.91.

5. Cutting calories and protein at the same time. A steep deficit with 60 grams of protein sheds muscle along with fat, and muscle is the tissue that keeps resting burn up. The 1.2 to 1.6 gram range exists to protect that tissue. If the protein target does not fit the calorie target, the deficit is too steep, not the protein too high.

One more quiet error sits behind all five: changing three things at once. Change the calorie target, keep the food the same for two weeks, then judge.

Where these numbers come from

Each figure on this page traces to a named institution and a year. If a source changes, the page changes with it.

The gaps between sources are worth naming. The AHA/ACC/TOS floors describe a prescribed diet for adults under care, not a universal minimum, and they were written for weight loss, not for athletes or for people recovering from illness. The protein range comes from a guideline written for the general public, while lifters and older adults often land at the top of it. The activity multipliers come from no single paper at all, which is why the NIDDK scale and the common 1.2 to 1.9 scale disagree.

Where the sources agree is the direction of travel: a deficit produces loss, the pace should sit near one to two pounds a week, protein protects lean mass, and a 5 to 10 percent loss already moves health markers. Those four statements hold across every document in the table.

This page is an estimate, not medical advice. It does not know your lab work, your medication list or your training history, and it should not replace a clinician who does.