TDEECalc estimates BMR with Mifflin–St Jeor (10 × kg + 6.25 × cm − 5 × age, +5 men or −161 women), multiplies it by an activity factor from 1.2 to 1.9 to get TDEE, then applies a percentage goal adjustment and a macro split. Weight change is converted at 7,700 kcal per kg. All results are estimates for adults aged 18 and over.
This page lists every calculation on the site, written the way the code implements it. The engine is a single TypeScript module. Its calculate function is a port of the iPhone app’s calculation engine, so the site and the app give the same TDEE, target and macros for the same inputs. Other functions add the formulas that the standalone calculators need.
Where a formula uses imperial inputs, they are converted first: 1 lb = 0.453592 kg and 1 in = 2.54 cm. Examples use the standard person: a 35-year-old woman, 5′5″ (165.1 cm), 165 lb (74.84 kg), moderately active.
How is BMR calculated?
The default is Mifflin–St Jeor (Mifflin et al., 1990; Frankenfield et al., 2005). Weight is in kilograms, height in centimeters and age in years.
Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5 Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
The site also offers two Harris–Benedict versions, the original 1918 equation and the 1984 revision (Harris & Benedict, 1918; Roza & Shizgal, 1984):
Original, men: 66.473 + 13.7516 × kg + 5.0033 × cm − 6.755 × age Original, women: 655.0955 + 9.5634 × kg + 1.8496 × cm − 4.6756 × age Revised, men: 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age Revised, women: 447.593 + 9.247 × kg + 3.098 × cm − 4.33 × age
When you supply body fat, two lean-mass equations become available (McArdle, Katch & Katch; Cunningham, 1980):
lean mass (kg) = weight (kg) × (1 − body fat % ÷ 100) Katch–McArdle: BMR = 370 + 21.6 × lean mass Cunningham: BMR = 500 + 22 × lean mass
| Equation | BMR, standard person |
|---|---|
| Mifflin–St Jeor | 1,444 kcal |
| Harris–Benedict revised (1984) | 1,500 kcal |
| Harris–Benedict original (1918) | 1,513 kcal |
Lean-mass equations need a body-fat percentage above 0% and below 50%. They are not shown for the standard person, who has no body-fat input.
What are the activity factors?
TDEE is BMR multiplied by one of five factors:
| Level | Factor | TDEE, standard person |
|---|---|---|
| Sedentary | 1.2 | 1,733 kcal |
| Light | 1.375 | 1,986 kcal |
| Moderate | 1.55 | 2,239 kcal |
| Active | 1.725 | 2,491 kcal |
| Athlete | 1.9 | 2,744 kcal |
These are the conventional multipliers used in nutrition practice. They are broad categories, so choosing the wrong level is the largest single source of error in a TDEE estimate.
How are goal calorie targets set?
The app’s calculate function applies a percentage to TDEE. The pace choice (0, 1 or 2) picks the percentage:
| Goal | Gentle | Recommended | Faster |
|---|---|---|---|
| Lose | −10% | −15% | −20% |
| Maintain | 0% | 0% | 0% |
| Gain | +5% | +10% | +15% |
target = TDEE × (1 + adjustment)
For the standard person at the recommended loss pace, the target is 2,239 × 0.85 = 1,903 kcal.
How are macros split?
Macros are a share of target calories. Protein and carbohydrate give 4 kcal per gram, and fat gives 9 kcal per gram.
| Goal | Protein | Carbs | Fat |
|---|---|---|---|
| Lose | 35% | 35% | 30% |
| Maintain | 30% | 40% | 30% |
| Gain | 25% | 50% | 25% |
protein g = target × protein share ÷ 4 carbs g = target × carb share ÷ 4 fat g = target × fat share ÷ 9
For the 1,903 kcal target on the loss split, that is 167 g protein, 167 g carbohydrate and 63 g fat. The standalone macro calculator also offers other presets and a protein-first mode, in which protein comes from grams per kilogram, fat from a share of calories and carbohydrate fills the remainder. These splits are practical defaults, not a published prescription. General intake guidance comes from the Dietary Guidelines (Dietary Guidelines 2020–2025).
What protein ranges does the site use?
Protein ranges are in grams per kilogram of body weight per day:
| Situation | g/kg/day |
|---|---|
| Minimum for most adults (RDA) | 0.8 |
| Regular exercise | 1.2 to 1.6 |
| Building muscle | 1.6 to 2.2 |
| Losing fat while lifting | 1.8 to 2.7 |
| Adults over 65 | 1.0 to 1.2 |
The ranges draw on sports-nutrition reviews and position stands (Morton et al., 2018; Jäger et al., 2017), and the fat-loss range on bodybuilding-preparation recommendations. The 1.8–2.7 g/kg of body weight is TDEECalc’s own conservative range; a contest-prep review for lean athletes recommends 2.3–3.1 g/kg of lean body mass (Helms et al., 2014). For a person with a high body-fat percentage the calculator can use a goal or adjusted weight instead of current weight. For the standard person, 1.8 to 2.7 g/kg is 135 to 202 g.
How is ideal body weight calculated?
Four formulas are shown side by side. Each uses the inches of height above 5 feet (60 in) and is defined from 5 feet (152.4 cm) upward. Results are in kilograms.
| Formula | Men | Women |
|---|---|---|
| Devine (Devine, 1974) | 50 + 2.3 per inch | 45.5 + 2.3 per inch |
| Robinson (Robinson et al., 1983) | 52 + 1.9 per inch | 49 + 1.7 per inch |
| Miller (Miller et al., 1983) | 56.2 + 1.41 per inch | 53.1 + 1.36 per inch |
| Hamwi (Hamwi, 1964) | 48 + 2.7 per inch | 45.5 + 2.2 per inch |
For the standard person (5 in over 5 feet) these give 57.0 kg (Devine), 57.5 kg (Robinson), 59.9 kg (Miller) and 56.5 kg (Hamwi). The app’s calculate function reports the Robinson value.
Adjusted body weight is used when actual weight is well above ideal:
adjusted = IBW + 0.4 × (actual − IBW)
For example, with an ideal weight of 70 kg and an actual weight of 100 kg, adjusted weight is 82 kg. These are historical formulas, not health targets. BMI is weight in kilograms divided by height in meters squared, with categories as published by the WHO and CDC.
How is body fat estimated?
The site uses the U.S. Navy circumference method (Hodgdon & Beckett, 1984), converted to inches, with a base-10 logarithm:
Men: %BF = 86.01 × log10(waist − neck) − 70.041 × log10(height) + 36.76 Women: %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Example: a woman of 165.1 cm with a 33 cm neck, 80 cm waist and 100 cm hips comes out at 32.2%. A man of 177.8 cm with a 38 cm neck and 90 cm waist comes out at 20.3%. Category labels use American Council on Exercise ranges as general guidance.
How is lean body mass estimated?
Three height-and-weight formulas are shown, with weight in kilograms and height in centimeters. Boer and Hume are cited (Boer, 1984; Hume, 1966). The James formula is also shown.
| Formula | Men | Women |
|---|---|---|
| Boer | 0.407 × kg + 0.267 × cm − 19.2 | 0.252 × kg + 0.473 × cm − 48.3 |
| James | 1.1 × kg − 128 × (kg ÷ cm)² | 1.07 × kg − 148 × (kg ÷ cm)² |
| Hume | 0.3281 × kg + 0.33929 × cm − 29.5336 | 0.29569 × kg + 0.41813 × cm − 43.2933 |
For the standard person: Boer 48.7 kg, James 49.7 kg and Hume 47.9 kg.
How are exercise calories calculated?
Exercise energy uses MET values from the Compendium of Physical Activities (Ainsworth et al., 2011; Herrmann et al., 2024):
gross kcal = MET × weight (kg) × hours net kcal = (MET − 1) × weight (kg) × hours
Gross includes the energy you would burn at rest, and net subtracts one MET for it. Brisk walking (4.3 METs) for an hour at 74.84 kg is 322 kcal gross and 247 kcal net. Workout calories should not be added on top of an activity factor, because the factor already includes typical exercise.
How are steps converted to calories?
Steps become distance through an estimated stride length, then distance becomes time at an assumed pace, then time becomes calories with a pace MET.
stride (cm) = height (cm) × 0.415 for men, × 0.413 for women distance (km) = steps × stride ÷ 100,000 hours = distance ÷ (pace mph × 1.609344) gross kcal = pace MET × kg × hours net kcal = (pace MET − 1) × kg × hours
| Pace | Speed | MET |
|---|---|---|
| Slow | 2.5 mph | 3.0 |
| Moderate | 3.0 mph | 3.5 |
| Brisk | 3.5 mph | 4.3 |
| Very brisk | 4.0 mph | 5.0 |
The stride ratios are commonly used estimates, and the pace METs come from the Compendium. For the standard person, 10,000 steps at a moderate pace is about 6.8 km in 85 minutes, or 370 kcal gross and 264 kcal net. Step counts are approximate (Tudor-Locke et al., 2011), and the stride estimate is a rough rule.
How does the weight projection work?
Energy balance is converted to weight at 7,700 kcal per kilogram, about 3,500 kcal per pound. The projection does not hold TDEE fixed. Each week it recomputes TDEE from the current weight, then updates weight:
TDEE(week) = Mifflin(age, current kg, height, sex) × activity factor weight(next week) = weight + (intake − TDEE) × 7 ÷ 7,700 age increases by 1 every 52 weeks
Because a lighter body burns less, loss slows. At 1,903 kcal a day, the standard person goes from 74.84 kg to about 73.65 kg after 4 weeks and 71.45 kg after 12. The slowing is the dynamic behavior described in the energy-balance literature (Hall et al., 2011; Thomas et al., 2014). It models a lower TDEE as weight falls, but not hormonal or behavioral adaptation. It is a planning approximation and not a forecast.
How is adaptive TDEE calculated?
Adaptive TDEE works backwards from what happened. If you ate a known average and your weight changed, the difference is your real expenditure.
slope = least-squares line through all logged weights (kg per day) observed TDEE = average logged intake − slope × 7,700
Using every weigh-in rather than two endpoints smooths water-weight swings. The tool also reports an uncertainty band:
residual = sqrt( sum of squared residuals ÷ max(1, n − 2) ) slope standard error = residual ÷ sqrt( sum of (x − mean x)² ) uncertainty (kcal/day) = slope standard error × 7,700
Confidence is labeled by data volume: high with a span of at least 28 days and at least 20 weigh-ins, medium with at least 14 days and 10 weigh-ins, otherwise low. It needs at least two weigh-ins and one intake entry. The app’s own adaptive engine is a separate on-device implementation with outlier handling and its own confidence stages. The website tool is the plain least-squares method described here. Read more in adaptive TDEE.
What is 7,700 kcal per kg?
It is the planning value for the energy content of body-weight change, equal to roughly 3,500 kcal per pound. It is a simplification, because the energy in lost weight varies with the mix of fat and lean tissue and with time. The dynamic projection and the adaptive calculation both use it as a constant, which is why their results are estimates.
How are results rounded?
The engine computes with full precision. Rounding happens only when a number is displayed, to whole numbers unless a calculator shows decimals. A displayed 1,903 kcal is 1,902.87 underneath. Because the example tables are rounded separately, a displayed total can differ from the sum of displayed parts by a unit.
How is the engine validated?
The engine has automated unit tests. A separate parity suite checks the website against the fixtures in the iOS app’s XCTest suite: Mifflin and fat-loss results, lean-mass equations, every activity factor, all goal paces, maintenance and gain macro ratios, imperial conversion and input boundaries. Other tests check each standalone formula against its published form and confirm that adaptive TDEE recovers a known expenditure. Source DOIs are checked against Crossref.
What are the limits?
- Estimates, not measurements. Equations predict average people. Individual expenditure often differs by several hundred calories a day.
- Activity level is a guess. The activity factor is a broad category.
- Equations are population-based. They were derived from specific groups and may fit unusual body compositions less well.
- Projections ignore adaptation. Metabolic and behavioral changes during dieting are not modeled.
- Adaptive results need good data. Missed logs, unlogged food and water weight widen the error.
Use any number as a starting point and check it against your weight trend. See the medical disclaimer.
Who are the calculators for?
TDEECalc is designed for adults aged 18 and over. The calculators accept ages 18 to 119, weights from 20 to 500 kg, heights from 100 cm to below 300 cm, and body fat above 0% and below 50%. Inputs outside these ranges are rejected. The equations are not validated for children or adolescents, and pregnancy and breastfeeding need individual guidance.
References
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 51(2):241–247.
- Harris JA, Benedict FG (1918). A biometric study of human basal metabolism. Proceedings of the National Academy of Sciences 4(12):370–373.
- Roza AM, Shizgal HM (1984). The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition 40(1):168–182.
- McArdle WD, Katch FI, Katch VL (2015). Exercise Physiology: Nutrition, Energy, and Human Performance (8th ed.). Wolters Kluwer Health.
- Cunningham JJ (1980). A reanalysis of the factors influencing basal metabolic rate in normal adults. American Journal of Clinical Nutrition 33(11):2372–2374.
- Frankenfield D, Roth-Yousey L, Compher C (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association 105(5):775–789.
- Hall KD, Sacks G, Chandramohan D, et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet 378(9793):826–837.
- Thomas DM, Gonzalez MC, Pereira AZ, Redman LM, Heymsfield SB (2014). Time to correctly predict the amount of weight loss with dieting. Journal of the Academy of Nutrition and Dietetics 114(6):857–861.
- Morton RW, Murphy KT, McKellar SR, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine 52(6):376–384.
- Jäger R, Kerksick CM, Campbell BI, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition 14:20.
- Helms ER, Aragon AA, Fitschen PJ (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition 11:20.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services (2020). Dietary Guidelines for Americans, 2020–2025 (9th ed.). DietaryGuidelines.gov.
- Devine BJ (1974). Gentamicin therapy. Drug Intelligence & Clinical Pharmacy 8:650–655.
- Robinson JD, Lupkiewicz SM, Palenik L, Lopez LM, Ariet M (1983). Determination of ideal body weight for drug dosage calculations. American Journal of Hospital Pharmacy 40(6):1016–1019.
- Hopefl AW, Miller DR, Carlson JD, Lloyd BJ, Day BJ, Tate M, Robinson JD, Lopez LM, Ramachandra CL (1983). Determining ideal body weight (and mass). American Journal of Hospital Pharmacy 40(10):1622–1627.
- Hamwi GJ (1964). Therapy: changing dietary concepts. In: Danowski TS, ed. Diabetes Mellitus: Diagnosis and Treatment. American Diabetes Association.
- Hodgdon JA, Beckett MB (1984). Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center reports (DTIC ADA143890, ADA146456).
- Boer P (1984). Estimated lean body mass as an index for normalization of body fluid volumes in humans. American Journal of Physiology–Renal Physiology 247(4):F632–F636.
- Hume R (1966). Prediction of lean body mass from height and weight. Journal of Clinical Pathology 19(4):389–391.
- Ainsworth BE, Haskell WL, Herrmann SD, et al. (2011). 2011 Compendium of Physical Activities: a second update of codes and MET values. Medicine & Science in Sports & Exercise 43(8):1575–1581.
- Herrmann SD, Willis EA, Ainsworth BE, et al. (2024). 2024 Adult Compendium of Physical Activities: a third update of the energy costs of human activities. Journal of Sport and Health Science 13(1):6–12.
- Tudor-Locke C, Craig CL, Brown WJ, et al. (2011). How many steps/day are enough? For adults. International Journal of Behavioral Nutrition and Physical Activity 8:79.