Calorie calculator for weight loss
Work out roughly what you burn in a day, and what to eat to lose weight at a steady rate. Enter your details in kilograms or in stone and pounds. Nothing you type is stored or sent anywhere.
The equation uses sex at birth, because it estimates from average body composition.
Maintenance, deficit and a realistic rate
Maintenance
The amount that keeps your weight stable. As a general guide the NHS puts the average at 2,000 kcal a day for women and 2,500 for men, though your own figure varies with age, weight, height and how much you move.
Deficit
Eating below maintenance so your body draws on its fat stores. Roughly 550 kcal a day below maintenance corresponds to about half a kilogram a week.
A realistic rate
Around 0.5 to 1 kg a week is the usual target. Faster is not better: very large deficits are harder to sustain and more likely to cost muscle alongside fat.
Why it changes
A lighter body burns less, so the deficit you started with narrows as you go. Recalculate every 4 to 5 kg rather than sticking to the first number.
What a calculator cannot tell you
Every calorie calculator uses a predictive equation built from population averages. For most people it lands within about 10% of reality, which is useful as a starting point and useless as a precise prescription.
It cannot account for thyroid problems, medicines that affect weight, pregnancy, eating disorders, or a history of yo-yo dieting. It does not know your body composition — two people of the same age, height and weight can have meaningfully different resting needs.
If your actual intake is far from the number here, or weight is changing in a direction you cannot explain, that is worth investigating rather than correcting by eating less. Unexplained weight change is a symptom in its own right.
Our guide to a safe rate of weight loss covers what to expect month by month, and the BMI calculator tells you where your weight currently sits against the adult ranges. If an underactive thyroid might be part of the picture, the thyroid symptom checker is a free place to start.
Frequently asked
How many calories should I eat to lose weight?
Enough below your maintenance level to create a steady deficit, without going so low that the diet is unsustainable or unsafe. A deficit of roughly 550 kcal a day corresponds to about 0.5 kg a week. The NHS gives average maintenance figures of 2,000 kcal a day for women and 2,500 for men, though your own figure depends on age, height, weight and activity.
How accurate is a calorie calculator?
It is an estimate from an equation, typically within about 10% for most people. It cannot account for individual metabolism, medical conditions, medicines or body composition. Treat the number as a starting point and adjust based on what actually happens over three to four weeks.
What is TDEE?
Total daily energy expenditure — everything your body uses in a day, including resting metabolism, movement, exercise and digesting food. It is your resting figure multiplied by an activity factor, and it is the number you eat below in order to lose weight.
What is BMR?
Basal metabolic rate: the energy your body uses at complete rest to keep basic functions going. It is usually the largest single part of your daily energy use, which is why someone sedentary still needs a substantial intake.
Is 1,200 calories a day safe?
For most adults, no, not without clinical supervision. Very low calorie diets are used in specific medical circumstances and are monitored. This calculator does not show targets below 1,400 kcal for women or 1,900 for men for that reason.
Why has my weight loss stopped even though I am in a deficit?
A lighter body needs fewer calories, so the deficit you started with shrinks as you lose weight. Water retention, changes in activity and inaccurate portion estimates also mask progress over short periods. Recalculate every 4 to 5 kg and judge progress over weeks rather than days.
How do I calculate weight loss percentage?
Divide the weight you have lost by your starting weight, then multiply by 100. Losing 5 kg from 90 kg is 5.6%. Clinically, a 5% to 10% loss is the point at which health markers such as blood pressure and blood sugar usually start to improve.
Sources
The health information on this page is based on UK guidance:
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