How to Use the Calorie Calculator
Use the calculator to estimate BMR, maintenance calories (TDEE), and a goal-based daily calorie target from your entered details.
- Choose Metric (cm / kg) or Imperial (ft-in / lb).
- Enter your height and weight, choosing the unit beside each value, then enter Age (years).
- Choose Male (default) or Female, an activity level, and a goal.
- Click Calculate Calories.
The initial selections are Male (default), Moderately active (moderate exercise 3-5 days/week), and Maintain weight.
Inputs, Units, and Controls
Height accepts cm, ft, or in, and Weight accepts kg or lb. The calculator also provides a Sex selector, five activity levels, and three goals.
Changing the unit or sex hides the current result, so click Calculate Calories again. Reset clears the entered fields, selects Male (default), and sets the first activity and goal options: Sedentary (little or no exercise) and Lose weight (-500 kcal/day).
What the Result Shows
After a valid calculation, the result section shows these rounded whole-number values:
- BMR (kcal/day)
- Maintenance (TDEE, kcal/day)
- Target for goal (kcal/day)
The formula and assumptions table then show the entered values, metric values used in the formula, age, sex, activity level, goal, multiplier, TDEE, and target. Imperial height and weight are converted to metric values in the result. The formula, assumptions, and actions remain hidden until a valid calculation.
Formula and Fixed Goal Adjustments
BMR uses the Mifflin-St Jeor equations:
Men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5
Women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161
Imperial inputs are converted before the formula is applied: 1 in = 2.54 cm and 1 lb = 0.45359237 kg. TDEE uses the selected activity multiplier:
- Sedentary:
1.2 - Lightly active:
1.375 - Moderately active:
1.55 - Very active:
1.725 - Extra active:
1.9
TDEE = BMR x activity multiplier. The goal adjustment is -500 kcal/day for Lose weight, 0 for Maintain weight, or +500 kcal/day for Gain weight:
Target = Math.max(0, TDEE + goal adjustment)
The target is therefore never below zero.
Validation and Recalculation
Height and weight must be finite numbers greater than zero. Age must be a whole number from 15 through 120. The selected unit beside each value determines its conversion before calculation.
The calculator does not apply a meaningful upper limit to height, weight, feet, pounds, or inches in its JavaScript validation. Missing or invalid values show an error and prevent the result.
Copying and Downloading the Result
Copy result copies the plain-text result when clipboard access succeeds. If it cannot copy, the message “Could not copy - select and copy manually.” appears.
Download result (.txt) downloads the plain-text result as calorie-calculator-result.txt.
Limits and Privacy Scope
This is a deterministic estimate based on the numbers entered, not medical advice. The visible disclaimer notes that actual needs vary with individual metabolism, body composition, and other factors, and recommends a healthcare professional or registered dietitian for a full assessment.
The calculator script performs the calculation in the browser and contains no request that sends calculator values. The inspected page also includes analytics and a subscription form, so this does not establish that nothing entered anywhere on the page is sent to a server.
The tool has no user-selectable formula, custom calorie adjustment, medical-condition adjustment, or body-composition input.
Frequently Asked Questions
How is BMR calculated?
This tool uses the Mifflin-St Jeor formula: for men, BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (years) + 5. For women, BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (years) - 161. If you enter imperial units, height and weight are first converted to metric before applying the formula.
What is TDEE and how is it calculated?
TDEE (Total Daily Energy Expenditure) is your estimated maintenance calories - the calories you burn in a day including activity. It is calculated as BMR multiplied by an activity factor ranging from 1.2 (sedentary) to 1.9 (extra active), based on the activity level you select.
How is the calorie target for my goal calculated?
The target applies a fixed daily adjustment to your TDEE: -500 kcal/day for weight loss, no change for maintenance, and +500 kcal/day for weight gain. The implementation uses Math.max(0, TDEE + goal adjustment), so the displayed target cannot be below zero.
Can I use imperial units instead of metric?
Yes. Choose ft or in beside Height and lb beside Weight. The values are converted to metric internally before the formula is applied, and the conversion is shown in the result.
What happens if I enter invalid values?
Calculation stops with an error if height or weight is missing, not finite, or not greater than zero. Age must be a whole number from 15 through 120. The selected units are applied to the entered values.