TDEE Formula and Calculation Steps

Review the TDEE formula, activity factor, calibration, BMR equations, scenario calculations, energy conversions, and a worked maintenance-calorie example.

How do the TDEE Calculator formulas work?

This formula page defines the variables used by the TDEE Calculator, shows how those values are combined, and explains the order of operations behind the result. Use the worked steps to verify an estimate, compare scenarios, and understand which assumptions or rounding rules can affect the displayed answer.

Formula Overview

TDEE=BMR\times AF\times\left(1+\frac{C}{100}\right)

BMR supplies the resting-energy starting point. AF is the user-entered activity factor, and C is the optional calibration percentage. When C equals zero, TDEE is simply BMR multiplied by AF.

Variable Definitions

Symbol	Meaning	Unit
W	Current body weight	kilograms
H	Height	centimeters
A	Age	completed years
F	Body-fat percentage	percent
LBM	Estimated lean body mass	kilograms
AF	Selected activity factor	multiplier
R	Activity-factor comparison range	factor units
C	Calibration adjustment	percent

Measurement Unit Conversions

W_{kg}=W_{lb}\times0.45359237

H_{cm}=(12\times feet+inches)\times2.54

The calculator converts U.S. measurements before applying a BMR equation. For the worked example, 175 pounds becomes 79.379 kg and 5 feet 10 inches becomes 177.80 cm.

Supported BMR Equations

Mifflin-St Jeor

BMR_{male}=10W+6.25H-5A+5

BMR_{female}=10W+6.25H-5A-161

Revised Harris-Benedict

BMR_{male}=88.362+13.397W+4.799H-5.677A

BMR_{female}=447.593+9.247W+3.098H-4.330A

Katch-McArdle

LBM=W\left(1-\frac{F}{100}\right)\qquad BMR=370+21.6(LBM)

Katch-McArdle uses estimated lean mass instead of age, height, and the sex-specific equation term.

Base TDEE Before Calibration

TDEE_{base}=BMR\times AF

The activity factor should represent average total activity for the period being estimated. The base result does not separately add exercise calories.

Calibration Multiplier

M_C=1+\frac{C}{100}\qquad TDEE=TDEE_{base}\times M_C

A calibration of 5% produces a multiplier of 1.05. A calibration of -5% produces 0.95. Zero leaves the base estimate unchanged.

Lower and Higher Activity Scenarios

AF_{low}=AF-R\qquad AF_{high}=AF+R

TDEE_s=BMR\times AF_s\times\left(1+\frac{C}{100}\right)

The engine validates that the lower factor remains at least 1 and the higher factor does not exceed 3. These scenarios are sensitivity calculations, not a statistical confidence interval.

Derived Energy Metrics

TDEE_{kJ/day}=TDEE_{Cal/day}\times4.184

TDEE_{week}=7\times TDEE_{day}\qquad TDEE_{hour}=\frac{TDEE_{day}}{24}

E_{above\ resting}=TDEE-BMR

Share_{above\ resting}=\frac{TDEE-BMR}{TDEE}\times100

The above-resting component is a model residual. It combines everything the multiplier and calibration place above BMR and is not a direct measurement of exercise or digestion.

Worked TDEE Calculation

A 30-year-old man who is 5 feet 10 inches tall and weighs 175 pounds selects Mifflin-St Jeor, activity factor 1.55, and calibration 0%.

10(79.37866)+6.25(177.80)-5(30)+5=1760.037

1760.037\times1.55\times(1+0)=2728.057

Output	Engine result
Estimated BMR	1760.037 Calories/day
Base TDEE	2728.057 Calories/day
Final TDEE	2728.057 Calories/day
Weekly equivalent	19096.398 Calories/week
Above resting estimate	968.020 Calories/day

Precision, Assumptions, and Limits

The engine retains precision through dependent calculations and rounds formatted displays.
Displayed precision does not imply that the activity factor or BMR is measured precisely.
The selected activity factor represents an average period rather than one unusually active day.
Calibration affects every displayed TDEE scenario.
Katch-McArdle depends directly on body-fat accuracy.
The model is static and does not predict metabolic adaptation or weight change over time.

TDEE Formula FAQ

Is TDEE always BMR multiplied by an activity factor?

That is the transparent static model used here. More detailed planning systems may model changes over time and use additional variables. For a useful TDEE Calculator formula result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

What does an activity factor of 1 mean?

It makes base TDEE equal to BMR. That mathematical boundary does not mean a person has no movement or food-processing energy in real life. Use realistic inputs and review the TDEE Calculator formula assumptions before relying on this result for decisions.

Does calibration change BMR?

No. Calibration changes TDEE and activity scenarios after BMR is calculated. The displayed selected BMR remains the equation output. For a useful TDEE Calculator formula result, use realistic inputs, compare relevant scenarios, and review the stated assumptions before making a decision.

References

Return to the TDEE Calculator or compare the three worked TDEE examples.

Use the TDEE Calculator