BMR vs TDEE: How to Estimate Your Daily Calories, Step by Step

By Ferdie Correa · Published October 5, 2026 · Last updated October 5, 2026 · 6 min read

Not medical advice. This article is general education, not a diagnosis or treatment plan. Talk to your doctor or a registered dietitian before making major changes to your diet, training or medication, especially if you have a health condition, are pregnant, or take prescription drugs.

Every calorie target FitStatsHub gives you starts with two numbers: BMR and TDEE. If either is off, the meal plan built on top of it is off by the same amount. This guide shows how both are calculated, works through two complete examples, and explains how to correct the estimate using your own scale data.

The four parts of daily energy use

BMR (basal metabolic rate): energy your body uses at complete rest to keep organs working, breathing and body temperature steady. For most people it is the largest part of the day's total.
NEAT (non-exercise activity thermogenesis): everything that is not formal exercise: walking to the car, cooking, standing, fidgeting. It varies a lot between people and tends to drop when you diet.
Exercise: planned training sessions. Often a smaller share than people expect.
Thermic effect of food: energy spent digesting and absorbing food, commonly estimated at around 10% of what you eat. Protein costs more to process than fat or carbohydrate.

TDEE (total daily energy expenditure) is the sum of all four. Calculators estimate it by multiplying BMR by an activity factor that stands in for the last three.

The Mifflin-St Jeor equation

FitStatsHub uses the Mifflin-St Jeor equation, published in 1990. A systematic review by Frankenfield and colleagues for the American Dietetic Association found it was the most reliable of the common prediction equations for healthy adults, in both non-obese and obese groups. It uses metric units:

Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

If you choose "Other" for sex in the planner, it uses −78, the midpoint between the two constants. To convert: kilograms = pounds × 0.4536, and centimeters = inches × 2.54.

Example 1: a 35-year-old woman

150 lb (68.0 kg), 5 ft 5 in (165.1 cm).

10 × 68.04 = 680.4
6.25 × 165.1 = 1,031.9
5 × 35 = 175
680.4 + 1,031.9 − 175 − 161 = 1,376 kcal per day

In metric with rounder inputs (68 kg, 165 cm) the result is 1,375 kcal, so the rounding barely matters.

Example 2: a 50-year-old man

200 lb (90.7 kg), 5 ft 11 in (180.3 cm).

10 × 90.72 = 907.2
6.25 × 180.34 = 1,127.1
5 × 50 = 250
907.2 + 1,127.1 − 250 + 5 = 1,789 kcal per day

With 91 kg and 180 cm the metric result is 1,790 kcal.

Activity multipliers, and why most people pick one too high

The planner's activity menu maps to these standard multipliers:

Planner option	Multiplier	Example week that fits	Woman (BMR 1,376)	Man (BMR 1,789)
Sedentary (desk-based)	1.2	Office job, drives everywhere, under about 5,000 steps a day, no training	1,652	2,147
Lightly active	1.375	Desk job plus 1 to 3 workouts of 30 to 45 minutes, or a daily 30-minute walk	1,892	2,460
Moderately active	1.55	3 to 5 solid workouts a week and a fair amount of walking, or a job on your feet	2,133	2,773
Very active	1.725	6 or more hard sessions a week, or a physically demanding job plus training	2,374	3,087
Athlete / intense training	1.9	Twice-daily training or endurance volume measured in many hours a week	2,615	3,400

The gap between neighboring rows is 250 to 400 kcal a day, roughly the size of a sensible calorie deficit. Picking one level too high can cancel out a diet entirely. The most common mistake is counting workouts but forgetting that the rest of the day is spent sitting. One hour in the gym does not make a desk worker "very active." When in doubt, choose the lower option and let your weigh-ins tell you whether to move up.

How accurate is the estimate?

Even the best equation is a population average. In the Frankenfield review, Mifflin-St Jeor predicted resting energy within 10% of the measured value for most people tested, but not for everyone, and errors were larger in some groups. For the woman above, 10% is about 140 kcal of BMR, which becomes more than 200 kcal once multiplied by an activity factor.

The multiplier adds its own uncertainty, since NEAT can differ by hundreds of calories between two people with the same job. So treat any calculated TDEE as a starting estimate with a margin of roughly 10 to 15% either way.

Calibrate the estimate against your own data

A two-to-three-week check gives you a far better number than any formula:

Eat close to a consistent calorie target and log it honestly, including drinks and cooking oil.
Weigh yourself each morning after using the bathroom and before eating or drinking.
Average each week's weigh-ins. Compare week 1 with week 3, not day 1 with day 21.
Convert the change. A common approximation is about 3,500 kcal per pound (about 7,700 kcal per kg) of body weight. It is rough, especially in the first weeks when water shifts, but usable for a correction.

Worked check: the woman above eats an average of 1,700 kcal a day. Her week-1 average is 150.4 lb and her week-3 average is 149.4 lb, a loss of 1.0 lb across 14 days. 1.0 × 3,500 ÷ 14 = 250 kcal a day deficit, so her real TDEE is about 1,700 + 250 = 1,950 kcal. That sits between the planner's "lightly active" (1,892) and "moderately active" (2,133) estimates, and it is the number to plan around.

If your weight did not move while eating below your estimated TDEE, your true maintenance is probably lower than the formula suggests, or intake is being undercounted. Both are common. Our guide to weight-loss plateaus covers how to tell which.

Reading the FitStatsHub output

After Step 1 on the planner, the Health Report shows:

BMR: the Mifflin-St Jeor result, labeled "calories/day at rest."
TDEE: BMR times the multiplier for the activity level you chose.
Healthy weight range and BMI, explained in What BMI can't tell you.
Protein floor, fiber target and hydration baseline, starting points for the meal plan.

In Step 2, your goal adjusts TDEE to a daily target: about 500 kcal below it for "Lose Weight," 320 below for "Get Ripped," 220 above for "Build Muscle," and 320 above for "Gain Weight." The planner will not set a target below 1,200 kcal. If you have calibrated your real TDEE from weigh-ins, compare it with the planner's figure. If they differ by more than about 150 kcal, try the next activity level up or down so the plan starts from the right baseline.

To choose a deficit size that fits you rather than a fixed 500 kcal, read How big should your calorie deficit be?

FAQ

Should I eat back the calories my watch says I burned?

Your activity multiplier already includes typical exercise. Adding watch estimates on top usually double-counts, and wrist devices often overestimate energy burned. Use weigh-in trends instead.

Does BMR drop as I lose weight?

Yes. A lighter body needs less energy, and the equation reflects that: every 10 lb (4.5 kg) lost lowers BMR by about 45 kcal before the multiplier is applied. That is one reason to regenerate your plan every two to four weeks.

Is BMR the same as RMR?

Resting metabolic rate is measured under slightly less strict conditions and comes out a little higher. Mifflin-St Jeor was developed from resting measurements, so in practice the terms are used interchangeably.