Every calorie target starts with one question: how much energy do you use on an ordinary day? This calculator answers it by estimating your basal metabolic rate and scaling it by your activity level, giving your total daily energy expenditure (TDEE). It then shows what gradual weight change would look like in calories and how a maintenance intake splits into carbohydrate, protein and fat.
How to use the calorie calculator
- Pick US or Metric units, then enter your sex, age, height and weight.
- Choose the activity level that matches a typical week.
- Leave the BMR equation on Mifflin–St Jeor unless you want to compare it with Harris–Benedict.
- Read your maintenance calories on the tape. The chart compares activity levels, and the tables show weight-change targets and macronutrient ranges.
How the estimate is built
The calculator first finds your basal metabolic rate (BMR) — for the default equation:
with weight in kilograms, height in centimeters and age in years. It then multiplies by an activity factor:
The factor bundles three things the BMR leaves out: exercise, everyday movement such as walking and standing, and the roughly 10% of intake spent digesting food. The BMR calculator explains the equations in more detail.
Worked example
A 35-year-old woman, 5 ft 5 in and 140 lb (165.1 cm, 63.5 kg), who exercises lightly two or three times a week:
BMR = 10 × 63.5 + 6.25 × 165.1 − 5 × 35 − 161 ≈ 1,331 kcal/day
TDEE = 1,331 × 1.375 ≈ 1,830 kcal/day
A 250-kcal daily deficit (about 0.5 lb a week) gives roughly 1,580 kcal/day; a 250-kcal surplus gives about 2,080.
For comparison, a moderately active 40-year-old man who is 180 cm and 80 kg has a BMR of 1,730 kcal and a TDEE of about 2,682 kcal/day.
Choosing an activity level
| Level | Factor | Typical week |
|---|---|---|
| Sedentary | 1.2 | Desk job, mostly sitting, little planned exercise |
| Lightly active | 1.375 | Light workouts or long walks 1–3 days |
| Moderately active | 1.55 | Moderate exercise 3–5 days |
| Very active | 1.725 | Hard training 6–7 days |
| Extra active | 1.9 | Physical job plus hard training, or two-a-day sessions |
The multipliers come from decades of energy-expenditure research and are widely used in nutrition practice, but they are broad bands. Two people who both “exercise three times a week” can differ by several hundred calories depending on intensity, step count and job.
Calorie targets and the 3,500-calorie rule
The weight-change table assumes a pound of body weight holds about 3,500 kcal (about 7,700 kcal per kilogram). That makes a 500-kcal daily gap roughly one pound per week at first. In practice, progress slows over time because a lighter body needs less energy and the body adapts, which is why researchers at the NIH built dynamic models instead of using a fixed rule. Very low intakes — below about 1,200 kcal a day for women or 1,500 for men — are generally followed only under medical supervision, and the table flags them.
Macronutrient ranges
The National Academies of Sciences set Acceptable Macronutrient Distribution Ranges for adults: 45–65% of calories from carbohydrate, 10–35% from protein and 20–35% from fat. The calculator converts those percentages to grams using 4 kcal per gram for carbohydrate and protein and 9 for fat. They are broad ranges associated with adequate nutrition, not a prescription for any single diet.
This calculator is informational only and is not medical or nutritional advice. Talk with a healthcare professional or registered dietitian before making major changes to how you eat, especially if you are pregnant, breastfeeding or managing a health condition.
Frequently asked questions
What does TDEE mean?
Total daily energy expenditure is every calorie you burn in a day: your basal metabolic rate, the energy used to digest food, planned exercise and all the incidental movement of daily life. Eating about your TDEE keeps weight roughly stable.
How accurate is a TDEE estimate?
For most adults it lands within about 10% of the true value, but individual differences in metabolism and activity mean some people fall outside that. Use the result as a starting point and compare it with how your weight actually changes over several weeks.
Does cutting 500 calories a day really lose a pound a week?
It is a reasonable short-term rule of thumb based on the estimate that a pound of body weight stores about 3,500 kcal. Over months, weight loss usually slows because a smaller body burns fewer calories, so the simple rule tends to overpredict long-term results.
Which activity level should I choose?
Choose based on a typical week, not your best one. Desk workers who exercise two or three times a week are usually lightly active. Most people overestimate activity, so if you are between two levels, the lower one is often closer.
Do the macronutrient ranges apply to everyone?
They are the National Academies' Acceptable Macronutrient Distribution Ranges for healthy adults. People with diabetes, kidney disease or other conditions, as well as competitive athletes, may have different needs and should get individual guidance.