Calorie Calculator

Food Energy Converter

The following converter can be used to convert between Calories and other common food energy units.

Calorie [Nutritional, kcal]Calorie [International Table, cal]Calorie [Thermochemical, cal]Kilojoules [kJ]Joules [J]Kilowatt-hours [kWh]British thermal units [BTU] =

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Calorie [Nutritional, kcal]Calorie [International Table, cal]Calorie [Thermochemical, cal]Kilojoules [kJ]Joules [J]Kilowatt-hours [kWh]British thermal units [BTU]

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How to use this calculator

1. Choose US Units or Metric Units. Switching converts figures you have already typed rather than clearing them.
2. Enter your age and select your gender.
3. Enter your height and weight.
4. Pick the activity level that best matches a typical week.
5. Press Calculate to see your maintenance calories, three rates of loss, and — behind the disclosure — three rates of gain.

+ Settings holds two choices most people never change: which of the three published BMR equations to use, and a body fat percentage for the one that needs it. Other Units opens a converter above the calculator for anyone whose scales read in stones; it is not a third unit system, and the calculator stays on whichever system you chose.

How your daily needs are worked out

The calculator first estimates your Basal Metabolic Rate — the calories you burn at rest — then multiplies it by an activity factor to reach your Total Daily Energy Expenditure (TDEE). TDEE is your maintenance level: eat that amount and your weight holds steady. The loss and gain targets are simply that number with a deficit or surplus applied.

The Mifflin-St Jeor formula

BMR is estimated with the Mifflin-St Jeor equation, then scaled by activity:

Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5

Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161

Maintenance (TDEE) = BMR × activity factor

• kg / cm — weight in kilograms and height in centimetres (imperial entries are converted for you)
• age — age in years
• activity factor — 1.2 for sedentary up to 1.9 for very active

Choosing your activity level

• Sedentary (1.2) — desk job, little or no exercise.
• Light (1.375) — light exercise 1–3 days a week.
• Moderate (1.55) — moderate exercise 3–5 days a week.
• Active (1.725) — hard exercise 6–7 days a week.
• Very active (1.9) — very hard exercise or a physical job.

When in doubt, pick the lower of two levels — most people overestimate how active they are, which inflates the target.

A worked example

Take a 30-year-old woman, 165 cm and 68 kg, who exercises a few times a week (moderate, 1.55). Her BMR is 10 × 68 + 6.25 × 165 − 5 × 30 − 161 ≈ 1,400, so her maintenance is 1,400 × 1.55 ≈ 2,170 calories a day. From there the calculator sets her loss and gain targets in 250- and 500-calorie steps:

Goal	Daily calories	Approx. weekly change
Lose faster	1,670	−0.5 kg (−1 lb)
Lose gradually	1,920	−0.25 kg
Maintain	2,170	—
Gain gradually	2,420	+0.25 kg
Gain faster	2,670	+0.5 kg (+1 lb)

Setting a loss or gain target

A pound of body fat stores roughly 3,500 calories, so a deficit of about 500 a day adds up to about a pound a week (500 × 7 = 3,500). That is why the calculator's targets step in 250- and 500-calorie increments. Gentler deficits are usually easier to sustain, and a surplus paired with resistance training favours muscle over fat.

Limitations to keep in mind

• Estimates, not guarantees. The equation predicts an average; adjust based on how your weight actually responds over a few weeks.
• Activity is self-reported. The factor is the biggest source of error — an honest, slightly conservative choice serves you better.
• Very low intakes. Extended, very-low-calorie diets need professional supervision, not a calculator.

To split your target across macronutrients, see the protein calculator and fat intake calculator. These are general estimates, not medical or dietary advice; consult a doctor or registered dietitian before making significant changes to your diet.