Calorie Calculator — daily intake target from maintenance

How it works

There are two numbers here and they do different jobs. Maintenance is what you burn: basal metabolic rate from the Mifflin-St Jeor equation, multiplied by the FAO/WHO/UNU physical activity level for your lifestyle. The target is what you plan to eat: maintenance shifted by whatever daily adjustment you set. Eat below maintenance and you are in a deficit; above it, a surplus.

Why this page won't tell you how fast you'll lose weight. Almost every calorie calculator converts a deficit into pounds per week using a rule that 3,500 kcal equals a pound of fat. That rule comes from a 1958 paper and is known to be wrong over anything but short periods, because it ignores how metabolism adapts as you lose weight — it consistently promises more loss than people actually get. Hall and colleagues, whose model underlies the NIH Body Weight Planner, found the bodyweight response to a change in intake is slow, with half times of about a year. We would rather show you no number than a number that over-promises, so the projection waits until we ship the dynamic model.

Worked example

Take the sedentary 30-year-old man at 170 cm and 70 kg. Mifflin-St Jeor gives a BMR of 1,618 kcal/day, and the sedentary lifestyle carries a PAL of 1.53, so maintenance is 1.53 × 1,618 = 2,475 kcal/day. Applying a 500 kcal deficit gives a target of 2,475 − 500 = 1,975 kcal/day, which is 80% of maintenance.

The consultation's own worked example runs the same way in SI units: a PAL of 1.75 against a BMR of 7.10 MJ/day (1,697 kcal/day) gives 12.42 MJ/day, or 2,970 kcal/day of maintenance energy.

Frequently asked questions

How big a deficit should I use?

That is a decision to make with a clinician who knows your history, not one a calculator should make for you. What the evidence does say about pace: CDC notes that people who lose weight at a gradual, steady pace — about 1 to 2 pounds a week — are more likely to keep it off than people who lose faster. Very large deficits also make it harder to meet your protein and micronutrient needs.

Why doesn't this show pounds per week?

Because doing that honestly needs a model of how your metabolism adapts, and the simple rule everyone uses doesn't have one. See the note above: the 3,500 kcal per pound rule over-predicts loss, and the error grows the longer you apply it. We are building the dynamic model as its own page rather than bolting a misleading projection onto this one.

What's the difference between this and the TDEE calculator?

The TDEE page answers how much energy you burn. This page starts from that same number and answers how much to eat given a deficit or surplus. If you only want the expenditure figure, use TDEE; if you are planning intake, use this.

Is there a minimum I shouldn't go below?

Yes, though the exact floor is individual. Very low intakes make it difficult to get enough protein, essential fats, vitamins and minerals, and they are normally used only under medical supervision. If your target here comes out very low, that is a sign to reduce the deficit or speak to a clinician rather than to proceed.

Does the target include exercise calories?

Yes. The activity level is already built into maintenance, because PAL is derived from total energy expenditure over a full 24 hours. You should not add exercise on top and eat it back — that would double-count it.

How accurate is the maintenance figure?

It is an estimate from two estimates: the BMR equation predicts a population average and can be off by 10% or more for an individual, and the activity level is a band rather than your measured value. Treat it as a starting point. If your weight is not moving as expected after several weeks of consistent intake, the maintenance estimate is the number to adjust.

What does this exclude?

It excludes pregnancy and lactation, growth in children and adolescents, illness and recovery, and any medical condition affecting metabolism. It also says nothing about food quality or how to split the target across protein, carbohydrate and fat — that is the macro calculator's job.