Calorie Calculator: How to Calculate Your Daily Calorie Needs for Weight Loss, Maintenance, or Muscle Gain

Your daily calorie target is not a guess — it is your Total Daily Energy Expenditure (TDEE): the calories you burn at rest plus the calories you burn through activity. A Calorie Calculator works this out from your age, sex, height, weight, and activity level, so you can set a target that actually produces results instead of relying on a generic 2,000-calorie figure.

How Calorie Needs Are Calculated

Online calculators use two steps. First they estimate your Basal Metabolic Rate (BMR) — the calories your body burns just keeping you alive — using the Mifflin-St Jeor equation:

• Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
• Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Then they multiply BMR by an activity factor to get your TDEE:

Activity Level	Multiplier	What Counts
Sedentary	1.2	Desk job, little or no exercise
Lightly active	1.375	1–3 workout days per week
Moderately active	1.55	3–5 workout days per week
Very active	1.725	6–7 hard sessions per week
Extra active	1.9	Physical job plus daily training

The most common mistake is overestimating activity. If you are not sure, pick the lower level — most people who work out 3 times a week are “lightly” or “moderately” active, not “very”.

A Real-World Example

A 30-year-old woman who is 5’5″ (165 cm) and 150 lb (68 kg) with light activity:

Step	Value
BMR (Mifflin-St Jeor)	≈ 1,405 kcal/day
Activity multiplier	1.375
Maintenance (TDEE)	≈ 1,930 kcal/day

Eating at 1,930 keeps her weight stable. To lose about 1 lb per week she would target ~1,430 (a 500-calorie deficit); to gain muscle slowly she would target ~2,200–2,400.

Set Your Goal: Deficit, Maintenance, or Surplus

Goal	Adjustment from TDEE	Expected Rate
Lose fat	−300 to −500 kcal	0.5–1 lb per week
Maintain	0 kcal	Stable weight
Build muscle	+200 to +400 kcal	~0.25–0.5 lb per week

Do not slash calories below ~1,200 for women or ~1,500 for men without medical supervision, and never cut more than 500 kcal below maintenance — aggressive deficits cause muscle loss, hormone disruption, and rebound weight gain.

Protein Still Matters

Whatever your target, aim for roughly 1.6–2.2 g of protein per kg of body weight when training — about 110–150 g/day for the 68 kg example above. Protein keeps you full, preserves muscle during a cut, and supports growth in a surplus. A simple split: ~30% protein, ~40% carbs, ~30% fat is a fine starting point for most people.

How to Adjust Based on Real Results

Any calculator is an estimate. Your actual maintenance may differ by 100–200 calories depending on genetics, muscle mass, and daily movement. Use this method:

• Eat at the calculated target for 2 weeks, tracking accurately (weigh food, don’t eyeball).
• Weigh yourself 3–4 times per week and average the readings — daily weight fluctuates with water.
• If weight is flat after 2 weeks and the goal is fat loss, drop 100–150 kcal; if losing too fast (over 1 lb/week), add 100–150 kcal.
• Re-calculate every 10 lb of weight change — your BMR shrinks as you get lighter.

Get your personalized number in under a minute with the Calorie Calculator — then build your meal plan around the result and adjust from real-world feedback, not guesswork.