TDEE Calculator & Macronutrient Planner

Understanding the TDEE Estimate

Total Daily Energy Expenditure is the energy used over a day, including resting functions, movement and processing food. Here, estimated resting expenditure is multiplied by a selected activity factor. The result is a starting estimate of maintenance intake. The calculator does not separately measure exercise calories or determine how much energy you absorb from food.

The output labeled BMR is a conventional calculator label for predicted resting expenditure. BMR and resting metabolic rate use different measurement conditions. In particular, Mifflin-St Jeor predicts resting energy expenditure; selecting it does not produce a clinical measurement of true basal metabolism. Decimal precision in the underlying arithmetic should not be confused with certainty about a person's needs.

Mifflin-St Jeor Formula

With mass $m$ in kilograms, height $h$ in centimeters and age $a$ in years, the implemented simplified equations are:

The original Mifflin study included healthy normal-weight and obese adults aged 19–78. The tool accepts 18–100 for adult planning, but displays an extrapolation advisory for Mifflin calculations outside 19–78. Input acceptance does not establish that the equation is validated for every age, body size or clinical condition.

Katch-McArdle in Advanced Mode

Enter body fat percentage to estimate lean mass, then select Katch-McArdle:

This is an alternative resting-energy estimate, not a guarantee of greater accuracy. An inaccurate body-fat measurement changes the estimate, and the tool cannot evaluate the quality of your measurement. A primary weight-loss trial analysis reports this equation and illustrates that findings depend on the prediction equation used. The two Advanced comparison outputs let you see the difference for the same profile.

Activity Factors: Explicit Assumptions

The calculator uses exactly three options:

These are rough calculator-selected scenarios, not measured PAL values, validated exercise-frequency categories or FAO's published tiers. No number of weekly workouts uniquely determines your daily expenditure. For comparison, FAO section 5.3 classifies sedentary/light lifestyles at 1.40–1.69, active/moderate at 1.70–1.99 and vigorous at 2.00–2.40. Its support for a PAL framework does not validate this calculator's three presets. The Lower option can underestimate expenditure for many free-living adults.

Use observed intake and longer-term weight trends to assess whether the selected scenario is plausible. Avoid treating a single day's scale change or one workout as a complete measure of activity.

Weight Loss, Maintenance and Gain

The goal control changes the estimate by a fixed amount:

These offsets are scenario assumptions, not a personalized recommendation or a promised rate of change. A surplus does not establish that the gained weight will be muscle. Likewise, a 500 kcal deficit does not guarantee one pound of fat loss every week. Hall and colleagues' dynamic model accounts for expenditure and body-weight responses changing over time.

The tool rejects candidate intake estimates below 1,000 kcal/day and shows an explanation instead of numbers. This product guard follows the lower-intake guard used by NIDDK's planner; passing it does not establish that an intake is suitable for you. Accepted estimates below 1,200 kcal/day for women or 1,500 for men show an additional review advisory. These review thresholds are screening rules, not universal physiological minimum requirements. Discuss a low intake estimate with a qualified clinician rather than using it automatically.

Turning Calories into Macro Grams

The two preset distributions allocate the complete intake estimate:

These are illustrative distributions, not individualized nutrient prescriptions. Advanced mode lets you select either split. Simple mode ignores hidden Advanced values and always uses Balanced and Mifflin-St Jeor.

Protein and carbohydrate use 4 kcal/g; fat uses 9 kcal/g. These are Atwater general factors, distinct from food-specific factors, as described by FAO's food-energy report. For example, Balanced protein grams equal $intakeEstimate \times 0.30 / 4$. The chart shows the same proportions and gram estimates as the numerical results. Independently rounding displayed grams can cause a small difference if you convert those rounded grams back to calories.

Worked Examples

Example 1: Default Male Profile, Weight Loss

For age 30, 170 lb, 70 in, Middle activity and Simple mode:

1. Convert mass: $170 \times 0.45359237 = 77.1107029$ kg; convert height: $70 \times 2.54 = 177.8$ cm.
2. Resting estimate: $10(77.1107029) + 6.25(177.8) - 5(30) + 5 = 1737.357029$ kcal/day.
3. Maintenance estimate: $1737.357029 \times 1.55 = 2692.90339495$ kcal/day.
4. Weight-loss estimate: $2692.90339495 - 500 = 2192.90339495$ kcal/day, displayed as 2,193.
5. Balanced macros: protein 164.4678 g, fat 73.0968 g, carbohydrates 219.2903 g, before display rounding.

BMI is $77.1107029 / 1.778^2 = 24.3922099$, displayed as 24.4. The total-water reference for this adult male profile is 3.7 L/day from food and drinks together.

Example 2: Metric Female Profile, Maintenance

For age 28, 60 kg, 165 cm, Middle activity and Simple mode:

1. Resting estimate: $600 + 1031.25 - 140 - 161 = 1330.25$ kcal/day.
2. Maintenance estimate: $1330.25 \times 1.55 = 2061.8875$ kcal/day, displayed as 2,062.
3. Balanced macros: protein 154.6416 g, fat 68.7296 g, carbohydrates 206.1888 g, before rounding.

The female maintenance preset loads these measurements. Selecting it preserves the current complexity mode, so select Simple when reproducing this example; Advanced uses the split stored by the preset.

BMI, Total Water and Measurement Units

BMI is mass in kilograms divided by squared height in meters. It is a size index, not a diagnosis or a measurement of body-fat percentage.

The water output is a population total-water reference, not an instruction to drink that much plain water. Food moisture and every beverage contribute. Institute of Medicine tables give 3.7 L/day for adult men and 2.7 for adult women; at age 18 the displayed values are the 14–18 group references, 3.3 and 2.3 respectively. Needs differ with heat, exercise and health. The calculator does not derive an individual hydration requirement from body weight.

US and Metric toggles preserve physical measurements without clamping them to a different body size. The equivalent data-entry domains are 60–700 lb (27.2155422–317.514659 kg) and 39–99 in (99.06–251.46 cm). Values can show additional decimals after conversion. A slider is a convenient approximate entry control; use the number field for a precise value. Blank or out-of-range input displays an error and clears numerical chart labels as well as results.

Frequently Asked Questions

Sources and Scope

• Mifflin et al. (1990): original resting-energy equation and study population.
• FAO/WHO/UNU (2004), adult energy requirements, section 5.3.
• FAO, food-energy conversion factors, section 3.5.1.
• Hall et al. (2011), dynamic body-weight model.
• NIDDK Body Weight Planner: population and lower-intake restrictions.
• Institute of Medicine (2005), Dietary Reference Intakes, Water chapter.
• Metabolic adaptation and prediction equations: primary trial analysis.