How Many Calories Do You Need a Day? BMR, Activity and Weight Goals

Calories are the energy in food. Eat more than your body uses and weight tends to rise; eat less and it tends to fall. The tricky part is knowing roughly how many your body needs. The free Calorie Calculator gives an estimate from your age, height, weight and activity level.

This is general information, not medical advice. If you have a health condition, talk to a doctor or dietitian.

Quick answer

Enter your age, sex, height, weight and activity level. The calculator finds your basal metabolic rate (BMR), adjusts it for activity and shows a calorie figure to maintain your weight, plus simple targets to lose or gain about half a kilo a week.

What is BMR?

Your basal metabolic rate is the energy your body burns at complete rest to keep you alive: breathing, circulation, temperature, cell repair. For most people it is the largest part of daily energy use. The tool uses the Mifflin-St Jeor formula, a widely used equation for estimating it.

From BMR to daily needs

BMR is multiplied by an activity factor to account for movement:

• Little or no exercise: mostly sitting, desk work.
• Light activity: light exercise one to three days a week.
• Moderate activity: exercise three to five days a week.
• Very active: hard exercise most days or a physical job.

The result is the calories you need to maintain your current weight.

Losing or gaining weight

About half a kilo of body weight corresponds to roughly 3,500 calories, so a daily change of about 500 calories leads to about half a kilo a week. The calculator shows these simple targets. Some practical points:

• Do not cut too hard. Very low intake can leave you tired, hungry and short of nutrients, and it is hard to sustain.
• Aim for gradual change. A slow, steady rate is more likely to last.
• Pay attention to food quality, such as protein, fibre, fruit and vegetables, not only the number.
• Keep moving. Activity helps health and mood independent of weight.

How to use the calculator, step by step

1. Open the Calorie Calculator.
2. Enter your age, height and weight, and your sex.
3. Choose your activity level honestly. Most people overestimate it.
4. Read the maintenance calories and the loss and gain targets.

Limits of any calculator

• It is an estimate. Real needs vary by person.
• It does not account for medical conditions, pregnancy or medicines.
• Check against reality. If you follow the estimate for a few weeks and your weight does not change as expected, adjust by 100 to 200 calories.

Related tools

• BMI Calculator for a quick screening number.
• BMR and Macro Calculator for protein, carb and fat targets.
• Water Intake Calculator for daily water.

Calories are not the whole story

Counting calories is a useful tool, but food quality shapes how you feel and how healthy you are. Two meals with the same calories can differ greatly in nutrition and in how filling they are.

• Protein helps you feel full and supports muscles.
• Fibre from vegetables, fruit, pulses and whole grains supports digestion and fullness.
• Healthy fats such as those in nuts, seeds and fish support the body's functions.
• Added sugar and refined flour raise calories quickly without keeping you full.

For protein, carbohydrate and fat targets, try the BMR and Macro Calculator.

Practical ways to eat within your target

1. Plan your meals for the day rather than deciding when hungry.
2. Fill half your plate with vegetables at lunch and dinner.
3. Choose water or unsweetened tea instead of sugary drinks.
4. Watch portions of oil, rice and fried snacks, which add up quickly.
5. Eat slowly, and stop when comfortably full.
6. Keep healthy snacks such as fruit, nuts and boiled eggs available.

Common mistakes

• Cutting calories too low, which leads to tiredness, cravings and rebound eating.
• Ignoring liquid calories from juice, sweet tea and soft drinks.
• Overestimating exercise. A one-hour walk burns less than many assume.
• Weighing yourself daily and panicking. Water weight causes normal swings.
• Expecting quick results. Steady change over months lasts.

Gaining weight healthily

If your goal is to gain weight, add about 300 to 500 calories a day from nutritious foods, such as milk, eggs, nuts and rice with pulses, and combine this with strength exercise to build muscle rather than only fat.

This guide is general information, not medical advice. People with medical conditions should follow their doctor's guidance.

Quick checklist

1. Enter honest numbers, especially activity.
2. Aim for gradual change.
3. Prioritise protein, fibre and water.
4. Re-check after four weeks.

A worked example: a sedentary office worker

Farhan is 30, 172 cm and 78 kg, and works at a desk with little exercise. The calculator gives a maintenance figure of about 2,100 calories a day. He wants to lose weight steadily, so he aims for roughly 1,700 to 1,800 calories, which is a moderate reduction. He plans three meals and one snack, increases vegetables and pulses, cuts sweet tea and fried snacks, and adds a 30-minute walk after dinner. After four weeks he has lost about 1.5 kg, which matches the estimate. He keeps the plan, checks again after another month and adjusts if progress stalls.

Safety notes

• Do not drop below a level your doctor advises, especially if you have a medical condition.
• If you feel dizzy or unwell, eat and speak to a professional.
• Children, teenagers, pregnant and breastfeeding women have different needs.

Frequently asked questions

What is the Mifflin-St Jeor formula? A commonly used equation that estimates BMR from age, sex, height and weight.

How many calories should I cut to lose weight? About 500 a day gives roughly half a kilo a week, but go gradually.

Is this medical advice? No. It is a guide.

Why is my activity level important? Because it changes the estimate by hundreds of calories.

Is it free? Yes, and it runs in your browser.

Is a very low-calorie diet a good idea? Not usually. It can cause nutrient shortages and is hard to sustain.

Do I need to count calories forever? No. Many people use counting for a short period to learn portions, then eat by habit.

How accurate is the estimate? It is a starting point. Adjust after a few weeks based on how your weight changes.

Do I need to eat back exercise calories? Not necessarily. The activity level in the calculator already accounts for your usual exercise.

Are all calories equal? For energy, yes; for health and fullness, food quality matters.

Next step

Open the Calorie Calculator below and find your starting estimate.