Why use this calculator
Generic calorie targets fail because they ignore the four things that actually determine your needs: size, age, sex and how much you move. A 1,200 or 2,000 calorie rule applied to everyone is either far too low for a large active person or too high for a small sedentary one, and both errors end the same way.
This calculator produces a number from your own inputs and shows the maintenance figure beside it, so you can see how large the deficit or surplus actually is rather than trusting a target in isolation. It also gives a weekly budget, which matters more in practice than the daily one. A heavy Saturday is not a failure if the week balances.
How to use it
- Set your units, then enter age, sex, weight and height carefully, because the estimate is sensitive to all four.
- Choose an activity level one step below your instinct, since self-rated activity is consistently overstated and this is where most of the error enters. Then pick your goal.
- Treat the result as a hypothesis to test over two weeks: eat at it, weigh yourself under consistent conditions, and compare weekly averages rather than daily readings.
- If nothing has moved after a fortnight, adjust by 100 to 200 calories rather than abandoning the approach entirely.
What each result means
- Expected weekly change
- How fast your weight should move at this target, using the 3,500 calories per pound rule. Real loss is usually a little slower than this once the first weeks pass.
- Daily Calories Target
- What to eat each day for your chosen goal. Test it for two weeks and adjust on the basis of your actual weight trend.
- Maintenance Calories
- Roughly what you burn in a day. Eating at this figure should hold your weight steady.
- BMR
- Energy used at complete rest. A floor rather than a target. Eating below it is rarely appropriate without supervision.
- Weekly Calorie Budget
- Your daily target times seven. Thinking weekly makes a heavy day recoverable instead of a reason to abandon the plan.
The formula
BMR is estimated with Mifflin-St Jeor: 10 x weight in kg + 6.25 x height in cm - 5 x age, plus 5 for men or minus 161 for women. Total daily energy expenditure multiplies that by an activity factor between 1.2 for sedentary and 1.9 for extra active. The goal then adjusts the total: a moderate deficit subtracts roughly 500 calories a day for about half a kilogram of loss a week, and a surplus adds the same. The weekly budget is the daily target multiplied by seven.
How this number is used in practice
What you eat inside the target matters as much as the number. Protein is the most satiating macronutrient and preserves muscle during a deficit, so 1.6 to 2.2 grams per kilogram of body weight makes the same calorie figure far easier to hold. Fibre from vegetables, legumes and whole grains does the same job by adding volume for the same energy. A target met entirely with highly processed food is numerically identical and practically much harder to sustain.
For most people the real value of counting is educational rather than permanent. A few weeks of accurate logging teaches what portions actually contain, and that knowledge usually survives long after the tracking stops. For anyone with a history of disordered eating, however, tracking can be actively harmful and the potential benefit does not justify the risk. Working with a practitioner on non-numeric approaches is the better path.
Worked examples
30 year old male, 5 ft 10 in, 176 lb, moderately active, maintaining
A target of 2,693 calories a day and a weekly budget of 18,850.
The same person aiming to lose weight
A target near 2,193 calories, a 500 a day deficit predicting roughly half a kilogram of loss a week.
35 year old female, 165 cm, 70 kg, lightly active, losing weight
Maintenance near 1,900 calories with a loss target close to 1,400.
When people use it
- Setting a starting calorie target for a weight goal
- Checking whether a diet plan is realistic for your body and activity
- Working out a maintenance figure after finishing a diet
- Adjusting intake after a change in training or a new desk job
- Planning a weekly budget rather than a rigid daily number
Tips
- Choose the activity level one step below your instinct. Overstating activity is the most common reason a target fails.
- Aim for 1.6 to 2.2 g of protein per kg of body weight; it preserves muscle and makes the target easier to hold.
- Use the weekly budget. A heavy day is recoverable across seven days and rarely matters on its own.
- Weigh under consistent conditions and compare weekly averages. Daily swings of 1 to 2 kg are water and food.
- Recalculate after every 5 to 10 kg of change, because a lighter body needs less energy.
- Losing faster than about 1 per cent of body weight a week costs more muscle and is harder to sustain.
What it assumes, and where it stops being accurate
- Population equations are used; individual metabolic rate varies by roughly 10 per cent either side.
- Activity multipliers are broad bands and carry more error than the underlying equation.
- The approximate 3,500 calories per pound rule overstates loss as body weight falls.
- Food label and logging accuracy are assumed; real-world under-reporting is common and substantial.
- Medical conditions, medication, pregnancy and breastfeeding change requirements and are not modelled.
Terms used on this page
- Calorie deficit
- Eating less energy than you expend, which is what produces weight loss.
- Maintenance calories
- The intake at which body weight stays roughly stable.
- Macronutrients
- Protein, carbohydrate and fat. The three energy-providing components of food.
- Satiety
- How full and satisfied a food leaves you, which varies a great deal at identical calorie levels.
Questions people ask
- How many calories should I eat to lose weight?
- A deficit of roughly 500 calories a day below maintenance predicts about half a kilogram of loss a week for most people. The right figure depends on your maintenance level, which this calculator estimates from your size, age, sex and activity. Aggressive deficits cost more muscle and are abandoned more often than they are completed.
- Is 1,200 calories a day safe?
- It is below the resting metabolic rate of most adults and is rarely appropriate without supervision. At that intake, hitting protein and micronutrient targets is difficult, muscle loss increases, and adherence collapses. Which is why very low intakes so often end in regain. A moderate deficit held for longer works better.
- Do I need to count calories forever?
- No, and most people should not. A few weeks of accurate logging teaches what portions actually contain, and that awareness usually persists without tracking. Long-term counting suits some people and is harmful for others, particularly anyone with a history of disordered eating.
- Why is my weight not moving at this target?
- Usually the deficit is smaller than it appears. A lighter body burns less, unconscious movement falls during a deficit, and logging accuracy drifts as portions creep up. Audit a few days carefully, recalculate at your current weight, then adjust by 100 to 200 calories rather than assuming the estimate was badly wrong.
- Does the type of food matter if the calories are the same?
- For weight change, calories dominate. For everything else, hunger, muscle retention, energy and health markers, composition matters a great deal. Adequate protein preserves muscle in a deficit, and fibre-rich foods provide volume for the same energy, which makes the same numeric target far easier to live with.
Use this with
Calorie Calculator answers one part of the question. These pick up where it stops: BMR Calculator, TDEE Calculator, Macronutrient Calculator and Water Intake Calculator.
Where these figures come from
This calculation is jurisdiction-neutral arithmetic. No country-specific rules are applied.
- Eat For Health: Australian Dietary Guidelines. Energy and nutrient reference values
- NHMRC: nutrient reference values for water. Adequate fluid intake figures
Calorie Calculator produces an estimate for general information. It is not financial, tax, medical, legal or engineering advice. read the full disclaimer. Spotted a wrong number? Report it and it gets fixed. The form picks up this calculator and the inputs you used.