How does the FAO/WHO/UNU report define physical activity level (PAL)?

Total energy expenditure divided by basal metabolic rate over 24 hours PAL = TEE ÷ BMR, the same kind of ratio as the calculator's multiplier.

With a BMR of 1,780 kcal, what does the moderate step (× 1.55) give?

2,759 kcal/day 1,780 × 1.55 = 2,759.

Which FAO/WHO/UNU band does a PAL of 1.55 fall into?

Sedentary or light activity (1.40–1.69) 1.55 sits inside the 1.40–1.69 range.

Module 1: Energy and caloriesLesson 2 of 136 min read

Activity multipliers explained: where 1.2 to 1.9 come from

A TDEE calculator does two things. It estimates the energy your body uses at rest, then scales that number up to cover a whole day of moving around. The scaling step is a single multiplier, picked from a short list of activity levels. That one number often changes the result more than any other input. This lesson explains what the multiplier stands for, how it compares with an international reference, and why it can only ever be rough.

The formula in one line

Total daily energy expenditure, or TDEE, is the energy used over 24 hours. The calculator first estimates resting energy with the Mifflin-St Jeor equation, then multiplies.

Mifflin and colleagues built their equation from 498 healthy adults measured at rest. It says nothing about activity. The multiplier adds that part in one step, covering work, chores, walking and exercise together. A multiplier of 1.55 means the day's total is 55% above the resting estimate.

TDEE

TDEE = BMR × activity multiplier. BMR (Mifflin-St Jeor) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5 for men or − 161 for women.

The five steps in the calculator

The ‘Activity level’ menu offers five choices. Each maps to one fixed multiplier:

Little or no exercise: × 1.2
Light exercise 1–3 days a week: × 1.375
Moderate exercise 3–5 days a week: × 1.55
Hard exercise 6–7 days a week: × 1.725
Very hard exercise or a physical job: × 1.9

Where the numbers come from

These five values are widely used rounded multipliers that appear in many calculators. They are a convention, not the output of one study. The closest published reference is the physical activity level (PAL) system of FAO, WHO and UNU, described below.

The FAO/WHO/UNU physical activity level

In 2004, a joint expert group of FAO, WHO and UNU published a report on human energy requirements. It expresses daily activity as a physical activity level, PAL, defined as total energy expenditure divided by basal metabolic rate over 24 hours.

That is the same ratio as the calculator's multiplier. The report groups lifestyles into three bands:

Sedentary or light activity lifestyle: PAL 1.40–1.69. Examples include office workers in cities who rarely do physically demanding tasks.
Active or moderately active lifestyle: PAL 1.70–1.99. Examples include construction workers, or desk workers who run or cycle for about an hour a day.
Vigorous or vigorously active lifestyle: PAL 2.00–2.40. Examples include manual farm laborers who work for hours with hand tools and carry heavy loads.

An upper limit

The report notes that PAL values above 2.40 are difficult to maintain over a long period of time.

Comparing the two scales

Put side by side, the calculator's steps sit lower than the FAO bands. The bottom step, 1.2, is below the 1.40 floor of the sedentary band. The light step, 1.375, also falls just under it. Moderate, at 1.55, lands inside the sedentary or light band. Hard, at 1.725, is in the active band, and very hard, at 1.9, is near its top.

One reason is the starting point. FAO's PAL is defined against basal metabolic rate. The calculator multiplies a Mifflin-St Jeor estimate of resting energy. The two scales describe the same idea but were not built on the same base, so they don't line up step for step.

Worked example

Man, 80 kg (176.4 lb), 180 cm (5 ft 10.9 in), 30 years. Mifflin BMR = 1,780 kcal/day. Moderate: 1,780 × 1.55 = 2,759 kcal/day. The full table: 1.2 gives 2,136; 1.375 gives 2,448; 1.55 gives 2,759; 1.725 gives 3,071; 1.9 gives 3,382 kcal/day.

Why any multiplier is rough

A multiplier squeezes a whole day into one number. Two people who both exercise three times a week can differ a lot. One may sit all day between workouts, the other may walk for hours at work.

The steps are also coarse. Moving from moderate to hard adds 0.175 to the multiplier, which is 312 kcal a day in the table for the man in the example. A real week often falls between two labels. Activity also changes from day to day, so the multiplier describes a typical day rather than any single one.

Errors stack. The BMR equation is itself an average for people like you, and the multiplier adds its own spread on top. That is why the calculator shows the whole table alongside the single answer. The formula is for adults and is not made for pregnancy or medical conditions that change energy use.

See your estimate at all five activity levels at once, with the multiplier for each row.

TDEE calculator

Quick check

Three questions. Pick an answer to see why.

How does the FAO/WHO/UNU report define physical activity level (PAL)?
Show the answer
Answer: Total energy expenditure divided by basal metabolic rate over 24 hours PAL = TEE ÷ BMR, the same kind of ratio as the calculator's multiplier.
With a BMR of 1,780 kcal, what does the moderate step (× 1.55) give?
Show the answer
Answer: 2,759 kcal/day 1,780 × 1.55 = 2,759.
Which FAO/WHO/UNU band does a PAL of 1.55 fall into?
Show the answer
Answer: Sedentary or light activity (1.40–1.69) 1.55 sits inside the 1.40–1.69 range.

Math, not advice

These guides explain published formulas and reference values. They are not medical advice, and the formulas aren't made for pregnancy, children or medical conditions. Each guide shows the date it was last checked.

Sources

Last checked October 27, 2026

Educational calculators based on published formulas. Not medical advice, diagnosis or treatment, and not made for pregnancy, children or medical conditions. Health disclaimer · Terms of use.