Based on your TDEE

Calorie Deficit Calculator

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1 kg fat ≈ 7,700 kcal · Safe floor: 1,200 kcal women · 1,500 kcal men
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These estimates are for informational purposes only and are not medical advice. Consult a registered dietitian or healthcare professional for personalized guidance.

What Is a Calorie Deficit?

A calorie deficit occurs when you consume fewer calories than your body burns throughout the day. Your body needs a certain number of calories just to maintain its current weight — this is your Total Daily Energy Expenditure (TDEE). When you consistently eat below that number, your body draws on stored energy (mostly body fat) to bridge the gap, and you lose weight over time.

The Math Behind It

One kilogram of body fat stores approximately 7,700 calories of energy. To lose weight, you need to create a cumulative deficit equal to that amount for every kilogram you want to lose:

A Real-World Example

Sarah has a TDEE of 2,400 kcal/day and wants to lose 0.5 kg per week.

Weekly deficit needed: 0.5 kg × 7,700 = 3,850 kcal/week

Daily deficit: 3,850 ÷ 7 = 550 kcal/day

Target daily intake: 2,400 − 550 = 1,850 kcal/day

By eating 1,850 kcal each day, Sarah can expect to lose about 0.5 kg per week — roughly 2 kg per month.

How This Connects to Your TDEE

Your TDEE is the foundation of any calorie deficit plan. Without knowing how many calories your body actually burns each day, any deficit target is just a guess. Your TDEE accounts for your basal metabolic rate, daily activity, exercise habits, and more.

If you haven't calculated your TDEE yet, start there first. Use our TDEE Calculator to get an accurate estimate, then come back here to set your deficit and build your weight-loss plan.

Once you know your deficit and daily calorie target, the next step is figuring out what to eat. A Macro Calculator helps you break your calorie budget into the right balance of protein, carbs, and fats to support your goals while preserving muscle mass.

Related Calculators

TDEE Calculator
Don't know your maintenance calories? Calculate your TDEE first — it's the foundation of your deficit.
BMR Calculator
Your BMR is the minimum calorie floor — never eat below it for extended periods without supervision.
Macro Calculator
Once you have your calorie target, split it into protein, carbs, and fat for your goal.
TDEE for Weight Loss
A TDEE calculator built specifically around fat loss — with deficit targets calculated for you.
How Many Calories to Lose Weight?
The science behind calorie deficits — safe ranges, the 7,700 kcal/kg rule, and worked examples.
What Is TDEE?
A complete explainer on Total Daily Energy Expenditure and why it's the number that matters most.

Frequently Asked Questions

What is a calorie deficit? +
A calorie deficit means consuming fewer calories than your body burns in a day. When you eat less than your Total Daily Energy Expenditure (TDEE), your body taps into stored energy — primarily body fat — to make up the difference, resulting in weight loss over time.
How many calories should I eat to lose weight? +
The number of calories you should eat depends on your TDEE and your weight-loss goal. A common approach is to subtract 500 calories per day from your TDEE to lose approximately 0.45 kg (1 lb) per week. For example, if your TDEE is 2,400 calories, eating around 1,900 calories per day would produce steady weight loss.
What is a safe calorie deficit? +
A safe calorie deficit is generally 500 to 750 calories per day, leading to a loss of about 0.5 to 0.75 kg per week. Most health professionals recommend that women do not eat below 1,200 calories per day and men do not eat below 1,500 calories per day without medical supervision.
How long does it take to lose 10 kg? +
At a safe and sustainable rate of 0.5 kg per week, losing 10 kg would take approximately 20 weeks (about 5 months). At a more aggressive but still reasonable rate of 0.75 kg per week, it would take roughly 13 to 14 weeks (about 3.5 months). Individual results vary based on adherence, metabolism, and other factors.
Is a 1,000 calorie deficit safe? +
A 1,000 calorie daily deficit is aggressive and can lead to a loss of about 1 kg per week. While it may be appropriate for some individuals under medical supervision, it can cause muscle loss, nutrient deficiencies, fatigue, and metabolic slowdown. Most experts recommend a moderate deficit of 500 to 750 calories per day for sustainable, healthy weight loss.
What happens if my calorie deficit is too large? +
An excessively large calorie deficit can lead to muscle loss, nutritional deficiencies, hormonal disruption, reduced metabolic rate, fatigue, and irritability. Very low calorie intake can also trigger binge eating and an unhealthy relationship with food. A moderate, sustainable deficit is more effective in the long run.