How Many Calories Should I Eat? — Complete Guide

"How many calories should I eat?" is one of the most common health questions — and the honest answer is: it depends. Your needs are shaped by your age, sex, height, weight, and activity level. The good news is that finding your personal number takes just a few minutes and a little simple math.

Step 1: Find your BMR

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest. It's the foundation of your calorie needs and typically accounts for 60–70% of the calories you burn each day. We calculate it with the Mifflin-St Jeor equation, the most accurate predictive formula available.

Step 2: Calculate your TDEE

Nobody lies in bed all day, so we multiply your BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE) — the total calories you burn in a typical day. This is your maintenance level: eat this much and your weight stays stable.

Step 3: Adjust for your goal

Once you know your TDEE, set your target:

Maintain weight: eat at your TDEE.
Lose weight: subtract 250–500 calories for a gentle, sustainable deficit.
Gain muscle: add 250–500 calories for a lean surplus.

A worked example

Consider a 30-year-old woman, 165 cm and 65 kg, who exercises 3–4 times a week. Her BMR is roughly 1,400 calories. Multiplying by a "moderately active" factor of 1.55 gives a TDEE of about 2,170 calories. To lose around half a kilo per week, she'd eat roughly 1,670 calories per day.

Average calorie needs

Group	Sedentary	Active
Women 19–30	1,800–2,000	2,400
Women 31–50	1,800	2,200
Men 19–30	2,400–2,600	3,000
Men 31–50	2,200–2,400	2,800–3,000

These are population averages. Your personal number from the calorie calculator will be more accurate.

Don't eat too little

Cutting calories too aggressively backfires: you lose muscle, your metabolism adapts downward, and hunger becomes unmanageable. As a floor, most experts advise not dropping below about 1,200 calories (women) or 1,500 calories (men) without medical supervision.

Recalculate as you go

Your calorie needs change as your weight changes. Recalculate every 4–5 kg (about 10 lb) of weight change to keep your targets accurate, and adjust based on what the scale and mirror actually show over 2–3 weeks.

Frequently asked questions

How many calories should I eat a day?

Most adults need between 1,600 and 3,000 calories per day depending on sex, size, age, and activity. The most accurate way to find your number is to calculate your TDEE, then adjust it for your goal.

Is 1,200 calories a day enough?

1,200 calories is the commonly cited minimum for women (1,500 for men) and is quite low for most adults. Eating too little can slow metabolism and cause muscle loss. Use a moderate deficit from your TDEE instead of an arbitrary low number.

How many calories to lose 1 pound a week?

A deficit of about 500 calories per day below your maintenance level produces roughly one pound of fat loss per week, since a pound of fat stores about 3,500 calories.