Calorie Deficit Calculator
A calorie deficit is eating fewer calories than you burn. This calculator estimates what you burn, then subtracts the deficit your chosen loss rate needs. For a 30-year-old man of 175 cm and 80 kg who is moderately active, it gives a BMR of 1,749 and a TDEE of 2,711, so losing 0.5 kg a week means eating about 2,161 calories a day.
Your Weight Loss Journey
How to Achieve Your Deficit
- • Combine diet and exercise for best results
- • Reduce daily calorie intake by: cal
- • Burn extra through exercise: cal
- • Track your progress weekly
⚠️ Warning: Target calories are very low. Consult a healthcare provider before following a very low-calorie diet.
About Calorie Deficit Calculator
The calculation runs in three steps and the page shows all of them. First your basal metabolic rate, using the Mifflin-St Jeor equation the tool implements: for men, 10 times weight in kilograms plus 6.25 times height in centimetres minus 5 times age plus 5; for women the same with minus 161 instead of plus 5. Second your total daily energy expenditure, the BMR multiplied by the activity factor you pick. Third the target, which is the TDEE minus the daily deficit your chosen rate of loss requires.
That last step rests on one assumption you should know about: the tool treats a kilogram of body fat as 7,700 calories. Losing 0.5 kg a week therefore needs 3,850 calories a week, which it divides by seven into a 550-calorie daily deficit. With the default profile — a 30-year-old man, 175 cm, 80 kg, moderately active — that gives a BMR of 1,749, a TDEE of 2,711 and a daily target of 2,161 calories, with 16,500 as the monthly deficit.
A weight-loss timeline follows from the same numbers. Going from 80 kg to a 70 kg target is 10 kg, which at 0.5 kg a week is 20 weeks, and the tool prints the date that lands on. Enter a target that is not below your current weight and it refuses to calculate and says so, because there is no deficit to plan.
There is one safety floor: the target never drops below 1,000 calories a day, and when the arithmetic would go lower the deficit is reduced instead. Beyond that, treat every figure as an estimate. The equation is a population average and individual metabolism varies; the 7,700-calorie rule ignores water, glycogen and muscle changes, which is why real weight moves unevenly week to week. This tool is not medical advice — talk to a doctor or a registered dietitian before starting a deficit, especially if you are pregnant, breastfeeding, under 18 or managing a medical condition.
Use Cases
How to use
Choose your sex and enter your age, height and current weight in the units you selected.
Enter a target weight lower than your current one; the tool refuses to plan without a goal in the losing direction.
Pick the activity level that matches an ordinary week, since it multiplies your BMR into the total you actually burn.
Choose a weekly rate of loss. The tool converts it into a daily deficit using 7,700 calories per kilogram.
Read the results: BMR, TDEE, the daily calorie target and the daily, weekly and monthly deficits behind it.
Check the weight-loss journey panel for the total to lose, the number of weeks and the projected goal date.
Pro Tips
- Re-run the calculation every few kilograms. A lighter body burns less, so the target that produced a deficit at 80 kg is closer to maintenance at 74 kg.
- The activity factor does most of the work. Moving from lightly to moderately active changes the TDEE by hundreds of calories, so pick the level that matches a normal week, not a good one.
- Loss rate and timeline are directly linked: 10 kg at 0.5 kg a week is 20 weeks, and doubling the rate halves the weeks but also doubles the daily deficit to 1,100 calories.
- If the target stops falling as you raise the rate, you have hit the 1,000-calorie floor: the tool caps the target there and shrinks the deficit instead of going lower.
- Set the target weight below the current weight or nothing is calculated. The error message says exactly that, because a deficit plan needs a goal in the losing direction.
Troubleshooting
It says the target weight must be lower than the current weight.
A deficit plan only makes sense towards a lower weight, so the tool stops rather than producing a nonsensical figure. Enter a target below your current weight. If you want to gain or maintain, this is the wrong calculator: a maintenance figure is the TDEE it already shows.
The daily target stopped changing when I chose a faster loss rate.
You have reached the built-in floor. The target never goes below 1,000 calories a day; when the arithmetic would take it lower, the tool holds the target at 1,000 and reduces the deficit instead. That is a signal the rate is too aggressive for your current expenditure.
I ate to the target and lost less than predicted.
The projection assumes a fixed 7,700 calories per kilogram and a metabolism that matches a population average. Real weight moves unevenly because of water and glycogen, activity is estimated rather than measured, and portions are hard to log exactly. Re-enter your current weight after a few weeks to get a fresh target.
Frequently Asked Questions
A calorie deficit means eating fewer calories than your body uses. Work out what you burn — your BMR multiplied by an activity factor — then subtract the deficit your target rate needs. With the default profile the tool shows a TDEE of 2,711 and a target of 2,161, a deficit of 550 calories a day.
That depends on what you burn, not on a fixed number. Enter your sex, age, height, weight, activity level and how fast you want to lose, and the tool subtracts the required deficit from your estimated expenditure. For the default 80 kg profile losing 0.5 kg a week, it lands on about 2,161 calories a day.
Target calories = TDEE − daily deficit, where TDEE is your BMR times an activity factor and the daily deficit comes from your chosen weekly rate. This tool converts the rate using 7,700 calories per kilogram, so 0.5 kg a week is 3,850 calories a week, or 550 a day.
With the Mifflin-St Jeor equation as implemented in this page: for men, 10 × weight in kg + 6.25 × height in cm − 5 × age + 5; for women the same with −161 in place of +5. A 30-year-old man of 175 cm and 80 kg gives 1,749 calories, which is what the BMR tile shows.
This calculator assumes 7,700, the figure behind the familiar 3,500 calories per pound, and every deficit and timeline it prints follows from it. It is a rule of thumb rather than a measured constant for any individual, which is one reason predicted and actual loss diverge.
Divide the weight to lose by the weekly rate. Going from 80 kg to 70 kg at 0.5 kg a week is 20 weeks, and the tool rounds up and prints the resulting date. Choosing a faster rate shortens the timeline but deepens the daily deficit in exact proportion.
No, and this page does not claim it is. It builds the deficit from your own estimated expenditure and your chosen rate, so the same 0.5 kg a week is a very different share of intake for a small, sedentary person than for a large, active one. Nothing here is medical advice.
It is an estimate built on two approximations: a BMR equation fitted to population averages, and a fixed conversion between calories and body mass. Individual metabolism varies, activity factors are self-reported, and food logging is imprecise. Use the number as a starting point and adjust it from what actually happens over several weeks.
Yes. Both the BMR equation and the activity multiplier scale with body weight, so a lighter body burns less. A target that created a 550-calorie deficit at 80 kg produces a smaller one at 74 kg. Re-entering your current weight every few kilograms keeps the plan honest.
Because it has a deliberate floor. When the chosen rate would push the target under 1,000 calories a day, the tool holds it there and shrinks the deficit instead. Very low intakes belong under professional supervision, so treat hitting that floor as a sign to slow the rate down and to speak to a doctor or dietitian.