Plateknow Two numbers from one equation. BMR is what your body spends doing nothing at all; multiply it by how much you move and you have maintenance — the calories that hold your weight where it currently is.
That is the target. The hard part is the other half — knowing what you actually ate.
Download freeThe formula, written out
This is Mifflin-St Jeor (1990). It is the equation most clinical practice reaches for because the American Dietetic Association’s evidence analysis found it predicted measured resting energy within 10% more often than the other standard predictive equations — and still missed by more than that for a meaningful minority of people.
- Men — 10 × weight in kg + 6.25 × height in cm − 5 × age + 5
- Women — 10 × weight in kg + 6.25 × height in cm − 5 × age − 161
It takes two sexes because those are the two groups it was fitted on. The equation is a statistical fit to a sample, and the field is not a statement about anything else.
The activity multiplier is the loose part
| Multiplier | What it describes |
|---|---|
| 1.2 | Desk job, little or no exercise |
| 1.375 | Exercise 1 to 3 days a week |
| 1.55 | 3 to 5 days a week |
| 1.725 | 6 to 7 days a week |
| 1.9 | Physical job, or two sessions a day |
These five are conventional, and they are the weakest link in the whole calculation. The step from 1.2 to 1.9 is a 58% swing on the same body, and "how much do you move" is not really a five-option question. Read the result as a starting bracket, not a figure.
What a calorie deficit is, and why this page will not pick one
A deficit is eating below maintenance. That is the entire definition — the number above, minus something.
What this page will not do is choose the something. A deficit is a target, and this site does not hand anyone a target they did not set. Not because a deficit is wrong for everybody, but because a web page knows nothing at all about who is reading it, and the review this product is designed against found that regular calorie-app use correlates with higher disordered-eating symptoms. If you want one, that is your decision and a clinician’s to advise on. The number above is what you would be measuring it from.
Fibre, and the numbers on the label
The result includes fibre because it is the intake most people are furthest from, and because the 2025–2030 Dietary Guidelines lead on it alongside protein. The rule is 14 g per 1,000 calories, the Adequate Intake in the Dietary Reference Intakes. The FDA’s Daily Value of 28 g is that same rule at the 2,000-calorie reference diet.
| Nutrient | Daily Value |
|---|---|
| Dietary fibre | 28 g |
| Protein | 50 g |
| Total fat | 78 g |
| Saturated fat | 20 g |
| Total carbohydrate | 275 g |
| Added sugars | 50 g |
| Sodium | 2,300 mg |
A Daily Value is a labelling reference so that one food can be compared with another. It is not a target for you, and the percentages on a packet are answering a different question from the one this calculator answers.
Why is my number different from another calculator?
Almost always the activity multiplier, which is the one input with no agreed definition. Some sites also use Harris-Benedict or Katch-McArdle instead of Mifflin-St Jeor, and Katch-McArdle needs a body fat figure most people are guessing at. If two calculators disagree, check which equation and which multiplier each one used before believing either.
Is TDEE how much I should eat?
No. It is how much holds your weight steady. What you should eat is a decision with a lot more in it than an equation, and this page does not make it for you.
How accurate is it?
For most adults a predictive equation lands within about 10% of measured resting energy, and for a meaningful minority it does not. Nothing on this page can tell you which group you are in. The only way to find out is to record what you actually eat over a few weeks and watch what happens.
Does the app do this for me?
The app fills in the other half — what you ate — from a photograph, and it has a mode that sets no calorie goal at all and simply records the day. The number from this page is yours to use or to ignore; the app does not require one.
Mifflin MD, St Jeor ST et al., A new predictive equation for resting energy expenditure in healthy individuals, Am J Clin Nutr (1990). Frankenfield D et al., American Dietetic Association evidence analysis of predictive equations for resting metabolic rate, J Am Diet Assoc (2005). Institute of Medicine, Dietary Reference Intakes (2005) — fibre Adequate Intake 14 g per 1,000 kcal. FDA, Daily Values on the Nutrition and Supplement Facts labels. Dietary Guidelines for Americans 2025–2030, released 7 January 2026. Disordered-eating finding: Flinders University systematic review, 38 studies, Body Image.