Calorie Calculator
Determine your maintenance calories and personalized targets for losing, maintaining, or gaining weight.
What is a Calorie Calculator?
A calorie calculator estimates how many calories your body needs each day to maintain, lose, or gain weight. This free tool starts with your Basal Metabolic Rate (BMR) — the energy your body burns at complete rest — then scales it by your activity level to find your Total Daily Energy Expenditure (TDEE), commonly called maintenance calories. Finally, it applies a calorie surplus or deficit based on the goal you select.
One pound of body fat stores roughly 3,500 calories, so a daily deficit of 500 calories adds up to about one pound of fat loss per week. By turning that math into clear daily targets, this calculator helps you set realistic, data-driven nutrition goals instead of guessing.
How to Use
- Select your gender and enter your age in years, height in centimeters, and weight in kilograms.
- Choose the activity level that best matches your typical week — be honest, because most people overestimate how active they are.
- Pick a goal: lose 0.5 or 1 lb per week, maintain your weight, or gain 0.5 or 1 lb per week.
- Click Calculate to see your maintenance calories, daily target, the difference, and the estimated time needed to change by one pound.
- Recalculate every few weeks — as your weight changes, so do your calorie needs.
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation, published in 1990 and widely regarded as the most accurate BMR formula for the general adult population:
Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5
Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161
- weight — body weight in kilograms (kg)
- height — height in centimeters (cm)
- age — age in years
- the constant — +5 for men, −161 for women — accounts for average differences in body composition between the sexes
The result is your BMR in calories per day: the energy needed to keep your heart beating, lungs breathing, and brain functioning even if you stayed in bed all day.
Activity Level Multipliers
To convert BMR into maintenance calories (your TDEE), multiply it by the factor that best describes your lifestyle:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job with little or no deliberate exercise |
| Lightly active | 1.375 | Light exercise or sports 1–3 days per week |
| Moderately active | 1.55 | Moderate exercise or sports 3–5 days per week |
| Very active | 1.725 | Hard exercise or sports 6–7 days per week |
| Extra active | 1.9 | Very hard training, a physical job, or twice-daily workouts |
If you are torn between two levels, pick the lower one and adjust after a few weeks based on how your weight actually responds.
Worked Example
Consider a 35-year-old man who weighs 80 kg, stands 180 cm tall, and exercises 3–5 days per week (moderately active).
Step 1 — BMR: BMR = 10 × 80 + 6.25 × 180 − 5 × 35 + 5 = 800 + 1,125 − 175 + 5 = 1,755 kcal/day
Step 2 — TDEE: TDEE = 1,755 × 1.55 ≈ 2,720 kcal/day — his maintenance calories.
Step 3 — Goal: To lose one pound per week, he selects a 500 kcal deficit: 2,720 − 500 = 2,220 kcal/day. At that intake, the 3,500-calorie-per-pound rule predicts about one pound of fat loss each week. Choosing the gentler 250 kcal deficit instead would set a target of 2,470 kcal/day and a pace of roughly half a pound per week.
For a woman with identical stats, the only change is the constant: BMR = 1,589 kcal/day and maintenance ≈ 2,463 kcal/day.
Safe Weight-Loss Guidelines
Keep the deficit moderate
A deficit of 250–500 kcal per day is the sweet spot for most people, producing roughly 0.25–0.5 kg (0.5–1 lb) of fat loss per week. Larger deficits accelerate muscle loss, intensify hunger, and are harder to sustain. Moderate, consistent deficits preserve more lean mass and lead to better long-term weight maintenance.
Respect minimum calorie floors
Without medical supervision, women should generally not eat below 1,200 kcal per day and men not below 1,500 kcal per day. Going lower makes it nearly impossible to meet vitamin, mineral, and protein needs, and can trigger metabolic adaptation. Avoid setting a target below your BMR for extended periods.
Prioritize protein and macros
When cutting calories, aim for about 1.6–2.2 g of protein per kilogram of body weight per day — for the 80 kg example above, roughly 130–175 g — to protect muscle and stay full. A balanced split for a 2,220 kcal weight-loss target is about 30% protein (≈165 g), 30% fat (≈74 g), and 40% carbohydrates (≈222 g). Use our Macro Calculator to fine-tune the split, and pair your diet with resistance training for the best body-composition results.
Frequently Asked Questions
How many calories should I eat to lose weight?
A safe and sustainable approach is to eat 250–500 calories below your maintenance level each day, which typically produces 0.5–1 pound (0.25–0.5 kg) of fat loss per week. Use the calculator above to find your maintenance calories, then subtract your chosen deficit.
What are maintenance calories?
Maintenance calories are the amount of energy you need to consume daily to keep your current weight stable. They equal your BMR multiplied by an activity factor, and they change as your weight, age, or activity level changes.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the energy your body burns at complete rest, while TDEE (Total Daily Energy Expenditure) adds the calories burned through daily movement and exercise. TDEE is the number that matters for setting weight-loss or weight-gain targets.
Is a 1,000 calorie deficit safe?
For most people, no. Very large deficits increase muscle loss, nutrient deficiencies, fatigue, and metabolic adaptation. A 1,000 kcal deficit may suit some individuals with higher body weights under professional guidance, but most adults do better with a moderate 250–500 kcal deficit.
What is the minimum number of calories I should eat?
Common minimums are 1,200 kcal per day for women and 1,500 kcal per day for men when dieting without medical supervision. Eating less makes it very difficult to cover essential nutrient needs and should only be done under the care of a healthcare professional.
Why does activity level matter?
Activity can swing your daily needs by hundreds of calories. Two people with identical BMRs can differ by 50% or more in TDEE if one is sedentary and the other trains daily, which is why this calculator asks about your typical exercise habits.
How much protein should I eat while cutting calories?
Aim for roughly 1.6–2.2 grams of protein per kilogram of body weight daily (about 0.7–1 gram per pound). Higher protein intake helps preserve muscle during a deficit and keeps you feeling full longer.