Calorie Deficit Calculator
Enter your gender, age, height, current weight, target weight and activity level. Get your maintenance calories, your daily target, a macro split and an honest date for reaching the goal.
Your details
The equation uses this because average lean mass differs. Pick whichever matches your physiology.
Metabolic rate falls roughly 5 kcal per year of age
Be honest here. Overstating activity is the single most common reason a deficit does not work.
Anything above 1% of body weight a week starts costing you muscle rather than fat.
Eat this many calories a day
1,580
calories per day
That is a deficit of 550 calories a day against your maintenance of 2,130.
1,549
BMR
at complete rest
2,130
Maintenance (TDEE)
to stay the same
10 kg
to lose
from 82 kg to 72 kg
23 wks
realistic timeline
20 weeks on paper
BMI now
29.1
Overweight
BMI at target
25.5
Overweight
A starting macro split
Protein is set at 1.8 g per kg of your target weight - high enough to protect muscle while you are in a deficit. Fat sits at 25% of intake; carbohydrate takes the balance.
130g
Protein
520 kcal
44g
Fat
396 kcal
166g
Carbs
664 kcal
What that deficit looks like on a plate
About 550 calories a day is roughly 3 festivals. You do not have to cut those specific things - it is just a sense of scale. Most people find it easier to remove one drink and one fried side than to overhaul every meal.
Eating in a deficit costs less, not more
Last Bite lets you buy surplus food from local restaurants and bakeries at up to 70% off. Smaller portions, lower cost, nothing thrown away.
Method: Mifflin-St Jeor equation for BMR, Harris-Benedict activity multipliers for TDEE, 7,700 kcal per kg of body fat for the projection. Timelines re-estimate maintenance at your target weight, which is why the realistic figure is longer than the on-paper one. This tool is general information, not medical advice. If you are pregnant, breastfeeding, under 18, or managing diabetes, heart disease or an eating disorder, speak to a doctor or registered dietitian before changing your intake. Nothing you enter is stored or sent anywhere.
How the calculator works
Three numbers do all the work. The first is your basal metabolic rate - what you would burn lying still in a dark room for twenty-four hours, keeping your heart beating and your body at temperature. For most adults that is between 55 and 70 per cent of everything they burn in a day. We calculate it with the Mifflin-St Jeor equation, which has been the recommended formula since a 2005 review found it more accurate than the older Harris-Benedict version for both lean and heavier adults.
The second is your total daily energy expenditure, or maintenance. That is your BMR multiplied by an activity factor between 1.2 for a desk job and 1.9 for hard physical labour or two training sessions a day. This is the step where most people go wrong, because almost everyone picks a factor one notch too high. A gym session three times a week does not make you very active if the other hundred and sixty-five hours are spent sitting.
The third is the deficit itself. A kilogram of body fat stores roughly 7,700 calories, so a daily gap of 550 calories predicts about half a kilogram a week. That figure is a planning tool rather than a law of physics - real loss is lumpier than that because of water, glycogen, salt, hormones and the simple fact that a lighter body burns less. The calculator handles the last of those by re-estimating your maintenance at your target weight and reporting the average, which is why the realistic timeline runs longer than the arithmetic one.
Frequently asked questions
How do I calculate my caloric deficit?
Work out your basal metabolic rate with the Mifflin-St Jeor equation, multiply it by an activity factor to get your total daily energy expenditure, then subtract the deficit you want. Because a kilogram of body fat holds roughly 7,700 calories, a deficit of 550 calories a day works out at about half a kilogram a week. This calculator does all of that from your gender, age, height, current weight, target weight and activity level.
How many calories should I eat to reach my target weight?
There is no single number - it depends on how big you are now, how tall you are, your age, your sex and how much you move. A 1.68 m woman of 32 who is lightly active and weighs 82 kg maintains at roughly 2,130 calories, so eating about 1,580 a day would take her towards 72 kg at half a kilogram a week - roughly 23 weeks once the slowdown is accounted for. Enter your own figures above to get your version.
Is a 500 calorie deficit enough?
For most people, yes. A 500 calorie daily deficit works out at roughly 0.45 kg or one pound a week, which is the pace most clinical guidance recommends. It is large enough to show on the scale within a fortnight and small enough that you can still eat normal meals, hit your protein target and keep training.
What is the lowest number of calories I should eat?
Standard guidance puts the floor at about 1,200 calories a day for women and 1,500 for men without medical supervision. Below that it becomes very difficult to meet protein, iron, calcium and B-vitamin needs, and a larger share of the weight lost is muscle rather than fat. This calculator will not set a target below those floors.
Why is the realistic timeline longer than the on-paper one?
Because maintenance calories fall as you get lighter. A person at 82 kg burns more at rest than the same person at 72 kg, so a fixed calorie target produces a shrinking deficit as the weight comes off. The calculator re-estimates your maintenance at the target weight and reports the average, which is why that figure runs longer than the simple division.
Can I lose weight and still eat Jamaican food?
Yes. Nothing about rice and peas, jerk chicken, callaloo, ground provisions or curry goat prevents a deficit. What tends to blow the budget is fried sides, sugary drinks and portion size rather than the dishes themselves. Steamed or roast provisions instead of fried, water or unsweetened tea instead of box drinks, and one scoop of rice instead of three will move most people into a deficit without changing what they cook.