Calorie Deficit Calculator

How to use the calorie deficit calculator

The calculator takes less than a minute. Follow these steps and you will get a daily calorie target you can start using today.

1. Pick your unit system. Choose metric (kilograms and centimetres) or US units (pounds, feet and inches). The labels update automatically.
2. Select your gender and enter your age. Both affect how many calories your body burns at rest.
3. Enter your current weight and height. Use a recent morning weight, after using the bathroom and before eating, for the most reliable number.
4. Choose your activity level. Be honest. Most people overestimate. If you are unsure, pick the lower option and adjust later based on real results.
5. Enter your goal weight. This is used to work out how much you need to lose and how long it will take.
6. Choose a weekly pace. Gentle and steady paces are easier to keep. Faster paces need bigger cuts and can leave you hungry and tired.
7. Press Calculate. You will see your BMR, maintenance calories (TDEE), daily calorie target, daily deficit, estimated goal date and a rough macro split.

Recalculate every 4 to 6 weeks. As you lose weight your body needs fewer calories, so your numbers will change.

How the calculator works

The tool follows four simple steps, each based on well-known formulas used by dietitians and fitness coaches.

Step 1: BMR with the Mifflin-St Jeor equation

Your basal metabolic rate (BMR) is the energy your body uses just to stay alive: breathing, circulating blood, repairing cells and keeping your temperature stable. The Mifflin-St Jeor equation is considered one of the most accurate estimates for healthy adults.

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

Step 2: TDEE with an activity multiplier

Total daily energy expenditure (TDEE) is your BMR multiplied by an activity factor. This is your maintenance level, the calories you eat to keep your weight the same.

Step 3: Convert weekly loss into a daily deficit

One kilogram of body fat holds roughly 7,700 calories (about 3,500 per pound). To lose 0.5 kg a week you need a weekly shortfall of about 3,850 calories, which is around 550 per day. The tool does this math for you.

Step 4: Set a safe daily target

Your calorie target equals TDEE minus the daily deficit. To protect your health, the calculator will not suggest less than 1,200 calories for women or 1,500 for men. If your chosen pace would go below that, the tool raises the target and shows a warning, and your goal date is recalculated using the real deficit.

These are estimates. The 7,700-calorie rule is a simplification, because your metabolism slows slightly as you lose weight. Treat the result as a starting point and adjust based on how your body responds.

What is a calorie deficit?

A calorie deficit happens when you consume fewer calories than your body burns. Your body needs a constant supply of energy. When food does not cover it, the body turns to stored fat to fill the gap. Do this consistently and body weight goes down.

There are three ways to create one: eat less, move more, or combine both. The combined approach usually works best. Cutting a small amount of food and adding daily walking is easier to sustain than starving yourself or exercising for hours.

The idea is simple, but it is not always easy. Hunger, social events, stress and sleep all affect how well you stick to a plan. A moderate deficit that you can follow for months will beat a harsh one that you quit after two weeks.

How big should your deficit be?

For most adults, a deficit of 300 to 750 calories per day is a sensible range. Here is how different sizes compare.

As a general rule, aim to lose around 0.5 to 1 percent of your body weight per week. Heavier people can lose faster. Lean people close to their goal should go slower to protect muscle.

Very large deficits can cause muscle loss, fatigue, poor sleep, hair thinning, low mood and nutrient gaps. They also tend to end in rebound eating. If you have a medical condition, are pregnant or breastfeeding, are under 18, or have a history of disordered eating, speak with a doctor or registered dietitian before cutting calories.

What to eat in a calorie deficit

Calories decide whether you lose weight. Food quality decides how you feel while doing it. These habits make a deficit easier.

Prioritise protein

Protein keeps you full and helps preserve muscle. A common target is 1.6 to 2.2 grams per kilogram of body weight per day. Good sources include eggs, chicken, fish, lentils, beans, yoghurt, paneer and tofu. The macro split shown in your results uses protein at 1.8 g per kg.

Fill up on fibre and volume

Vegetables, fruit, oats, beans and whole grains give a lot of food for few calories. Start meals with a salad or soup and you will often eat less without feeling deprived.

Watch liquid calories

Sugary drinks, juice, sweet tea, milkshakes and alcohol add calories fast and do little for fullness. Swapping them for water, unsweetened tea or black coffee is one of the easiest ways to create a deficit.

Control portions, not whole food groups

You do not have to give up rice, bread, or your favourite foods. Reduce portion sizes, use a smaller plate and measure oils, nuts and spreads, because these are very calorie-dense.

Add movement

Walking 7,000 to 10,000 steps a day, strength training two or three times a week and sleeping seven to nine hours all support fat loss. Strength training matters most because it tells your body to keep muscle while it loses fat.

Common calorie deficit mistakes

• Cutting too low. Extreme diets backfire through hunger, binge eating and muscle loss.
• Not tracking honestly. Cooking oil, snacks, bites while cooking and weekend meals are often forgotten.
• Overestimating exercise. Gym machines and watches often overstate calories burned. Do not “eat back” all of them.
• Judging by daily weight. Water, salt and hormones move the scale by 1–2 kg. Look at weekly averages instead.
• Ignoring sleep and stress. Poor sleep raises hunger hormones and makes cravings stronger.
• Never taking a break. After 8 to 12 weeks, a week at maintenance can help with adherence and energy.
• Skipping strength training. Without it, more of the weight you lose can be muscle.

What if the scale stops moving?

Plateaus are normal. Check that you are still tracking accurately, recalculate your numbers at your new weight, add some daily steps, and give it two to three weeks before making changes.

About this tool

The Calorie Deficit Calculator is a free online tool that estimates how many calories you should eat each day to lose weight at a pace you choose. It combines the Mifflin-St Jeor BMR equation, standard activity multipliers and the 7,700 calories-per-kilogram rule to give a clear, practical plan. It works with metric and US units, runs fully in your browser, and does not store or send your personal data anywhere.

The page is built to be light and fast, so it loads quickly even on slow mobile connections, and it works well on phones, tablets and desktop computers.

Disclaimer: This calculator gives general estimates for healthy adults and is for information only. It is not medical advice. Always consult a qualified healthcare professional before starting a weight loss plan, particularly if you have a medical condition, take medication, are pregnant or breastfeeding, or are under 18.

Frequently asked questions