A calorie deficit is the foundation of every successful weight loss plan. By eating fewer calories than your body burns each day, you force it to tap into stored body fat for energy. This calculator estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, then subtracts your chosen deficit to produce a daily calorie target and a projected timeline to reach your goal weight.
Calculate Your Calorie Deficit
Your Weight Loss Plan
| Your TDEE (maintenance) | — |
| BMR (basal metabolic rate) | — |
| Daily calorie deficit | — |
| Weekly calorie deficit | — |
| Daily calorie target | — |
| Weight to lose | — |
| Estimated time to goal | — |
| Projected goal date | — |
Calorie Comparison
Projected Progress Timeline
Timeline assumes a constant deficit. In reality, weight loss slows over time as your TDEE decreases. Recalculate periodically for updated estimates.
How to Use the Calorie Deficit Calculator
Losing weight comes down to one fundamental principle: eating fewer calories than your body burns. The tricky part is figuring out exactly how many calories that is for your unique body and lifestyle. This free calorie deficit calculator takes the guesswork out of the equation by computing your precise daily calorie target and giving you a realistic timeline to reach your goal weight.
Step 1: Choose Your Units
Toggle between metric (kilograms and centimeters) and imperial (pounds and feet/inches) using the switch at the top of the form. The calculator handles all conversions automatically, so use whichever system you are most comfortable with.
Step 2: Enter Your Body Stats
Fill in your age, gender, height, current weight, and goal weight. These values feed into the Mifflin-St Jeor equation, the gold standard for estimating Basal Metabolic Rate (BMR). Your BMR represents the calories your body needs at complete rest just to keep your organs functioning, blood circulating, and lungs breathing.
Step 3: Select Activity Level and Rate
Choose the activity level that honestly reflects your typical week. Then pick your desired weight loss rate. A rate of 1 pound per week (500-calorie daily deficit) is the most commonly recommended pace for sustainable fat loss. Faster rates create larger deficits, which can be harder to maintain and may lead to muscle loss if protein intake is not carefully managed.
Step 4: Review Your Results
After clicking Calculate, you will see your daily calorie target, the size of your deficit, how many weeks it will take to reach your goal, and a projected target date. The progress timeline shows estimated weight at regular intervals so you can set intermediate milestones. If your selected rate would push your intake below the safe minimum (1,200 calories for women, 1,500 for men), the calculator automatically caps your deficit and shows a warning.
Tips for Success
Weigh yourself at the same time each day (morning, before eating) and use a weekly average to track progress. Recalculate your calorie deficit every time you lose 5 kg (10 lbs), because your TDEE drops as your weight decreases. Pair your deficit with adequate protein intake (0.7-1 g per pound of body weight) and resistance training to preserve muscle mass while losing fat. Remember that consistency over weeks and months matters far more than perfection on any single day.
FAQ
Is this calorie deficit calculator free to use?
Yes, the Calorie Deficit Calculator is completely free with no limits. You can calculate your deficit, daily calorie target, and weight loss timeline as many times as you want. No signup required and everything runs locally in your browser.
Is my personal data safe and private?
Yes, all calculations run entirely in your browser using client-side JavaScript. Your weight, height, age, and other personal details are never sent to a server, never stored in a database, and never shared with anyone. Once you close the page, your data is gone.
What is a calorie deficit and how does it cause weight loss?
A calorie deficit means you consume fewer calories than your body burns each day. When this happens, your body draws on stored energy (primarily body fat) to make up the difference. A deficit of approximately 3,500 calories results in about one pound of fat loss, which is why a 500 calorie daily deficit leads to roughly one pound per week of weight loss.
How many calories should I eat to lose weight?
Your daily calorie target depends on your Total Daily Energy Expenditure (TDEE) minus your chosen deficit. A moderate deficit of 500 calories per day (about 1 lb/week) is considered safe and sustainable. This calculator computes your exact target based on your stats, activity level, and preferred rate of weight loss.
Is losing 2 pounds per week safe?
For most people, losing up to 2 pounds per week is considered the maximum safe rate by most health organizations. However, this creates a 1,000-calorie daily deficit which may be too aggressive for smaller or less active individuals. This calculator enforces a minimum of 1,200 calories for women and 1,500 for men to protect against nutritional deficiencies.
What activity level should I choose?
Choose Sedentary if you have a desk job and do not exercise. Lightly Active means light exercise 1 to 3 days per week. Moderately Active is moderate exercise 3 to 5 days per week. Very Active is hard exercise 6 to 7 days per week. Extra Active is for athletes or people with physically demanding jobs who also train daily.
Why does the calculator show a minimum calorie floor?
Eating too few calories can lead to muscle loss, nutrient deficiencies, metabolic slowdown, and other health problems. The calculator enforces a minimum of 1,200 calories per day for women and 1,500 for men, in line with general medical guidelines. If your chosen rate of loss would drop you below this floor, the calculator caps your deficit and shows a warning.
How accurate is this weight loss timeline?
The timeline is a mathematical estimate based on a constant deficit. In reality, weight loss is not perfectly linear due to water retention, metabolic adaptation, and changes in body composition. Use the projected date as a rough guide and recalculate every few weeks as your weight changes, since your TDEE decreases as you lose weight.