You’ll lose weight only if you consume fewer calories than your body burns, and the precise figure varies with your age, height, weight and activity level. This guide shows how to calculate it and what to do with the number once you’ve got it. Skip the sums and use our free Calorie Calculator to get your target straight away.
Understanding calories to lose weight
Your body uses calories for everything—breathing, walking, even digesting food. Eat more than you burn and the surplus turns to fat. Eat less than you burn and your body raids those fat stores to make up the shortfall. That’s all there is to it. To shed weight, you need a calorie deficit, but how big should it be? Aim for a safe, steady loss of about 0.5kg a week, which means cutting roughly 500 calories each day from your normal intake. That’s not starvation—just eating slightly less than your body needs.
Take a 35-year-old woman, 165cm tall, weighing 75kg, who walks to the shops a few times a week. Her body burns about 2,100 calories daily just to keep her alive and moving. If she eats 1,800 calories instead, she runs a 300-calorie daily deficit. Over seven days, that’s 2,100 fewer calories, or about 0.3kg of fat loss. To reach 0.5kg a week, she’d need a 500-calorie daily deficit, so she’d set a target of 1,600 calories. The calculator does the sums in seconds.
How to work it out, step by step
- Enter your gender, age, weight and height.
- Pick your activity level.
- Choose your goal.
- See your daily calorie target and the maintenance range.
Calories = Mifflin-St Jeor BMR × activity, then ±500 for weight goalsWhy it matters
Most people wildly misjudge their calorie needs. They think a small salad is a full dinner or that a pint of beer has no calories at all. Those tiny slip-ups add up, and before they know it the scales won’t budge even when they’re ‘eating healthy’. A sensible calorie target keeps you honest without turning life into a numbers game—just a gentle nudge to steer your habits in the right direction.
Free tools for this
| Tool | What it does |
|---|---|
| Calorie Calculator | Find your daily calorie target to maintain, lose or gain weight. |
| BMR Calculator | Find how many calories your body burns at rest and each day. |
| BMI Calculator | Find your Body Mass Index (BMI) and weight category in seconds. |
Try the Calorie Calculator
Skip the manual maths — enter your numbers and get the answer instantly.
Open the Calorie Calculator →Good to know
Remember that these figures are general guides, not medical advice. Bodies differ, so treat the result as a starting point and speak to a qualified professional before making decisions about your health.
Key takeaways
- Work out your maintenance calories first, then subtract 500 for a safe weekly weight loss of about 0.5kg.
- Track what you eat for a few days—scales and apps don’t lie like memory does.
- Adjust as you go; if the scales stall after a month, cut another 100–200 calories or move a bit more.
Frequently asked questions
Which formula does this use?
Mifflin-St Jeor for BMR, then a standard activity multiplier from 1.2 (sedentary) to 1.9 (extra active) to reach TDEE. The goal adjustment is a flat ±500 kcal.
Why is my number different from another calculator?
Different sites use different equations — Harris-Benedict and Katch-McArdle are the common alternatives — and different activity multipliers. The spread between them is normal and tells you how approximate all of them are.
Is a 500 calorie deficit right for everyone?
No. It is a convenient round number, not a personalised prescription. What is appropriate depends on your size, health and circumstances, which this page knows nothing about.
Why did my weight stall even though I hit the number?
Because the number was an estimate. Real energy needs vary between people with identical inputs, activity is hard to self-assess, and needs shift as body weight changes. Adjust using the results you observe rather than the calculation.
Does it account for medical conditions?
Not at all. It is arithmetic on four inputs. If you have a health condition, are pregnant, or take medication that affects weight or appetite, talk to a doctor or dietitian instead.
