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Calorie & Protein Calculator

Most adult women maintain their weight on about 1,600 to 2,400 kcal a day and most men on about 2,000 to 3,000; this tool estimates your own number, a sustainable fat-loss deficit, and a protein range matched to your goal as rough, population-based starting points.

What's your goal?

Individual needs vary, and the equations are less accurate at the extremes of body size. Talk to a doctor or registered dietitian before starting a diet, especially with a health condition, an eating-disorder history, or during pregnancy. These numbers are general orientation, not a meal plan or treatment; don't use them to change any medical or therapeutic regimen, and discuss any change with your doctor or dietitian.

This tool isn't built for you if you are pregnant, breastfeeding, under 18, or have a history of disordered eating. Please get individual guidance from a doctor or dietitian instead.

If counting calories or hitting a number ever feels distressing, you are not alone. Please reach out to a doctor or an eating-disorder helpline.

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Most adult women maintain their weight on about 1,600 to 2,400 kcal a day and most adult men on about 2,000 to 3,000, depending on age, body size and activity. This tool estimates your own maintenance (TDEE) with the Mifflin-St Jeor equation, then a fat-loss deficit of about 300 to 500 kcal a day and a protein range matched to your goal, from 0.8 to 2.2 g per kg. It is a starting point, not a promise.

How many calories do I need a day?

Most adult women maintain their weight on roughly 1,600 to 2,400 kcal a day and most adult men on roughly 2,000 to 3,000 kcal, depending on age, body size and daily movement (estimated calorie needs, Dietary Guidelines for Americans 2020 to 2025). Those population ranges hide a large individual spread, which is why a calculated estimate beats any generic rule: this calculator estimates your personal maintenance from your sex, age, height, weight and activity, then shows what to eat for fat loss (a 300 to 500 kcal deficit) or muscle gain (a small surplus). To lose weight you eat below maintenance; many women land near 1,400 to 1,900 kcal a day and many men near 1,700 to 2,500, but your own number can sit well outside those bands, so calculate rather than copy an average.

Full guide: how many calories you need a day

How big a deficit should you use?

A moderate deficit of roughly 300 to 500 kcal a day works out, by the 7,700 kcal per kg rule, to about 0.3 to 0.6% of bodyweight a week for most adults. Sports-nutrition guidance names 0.5 to 1.0% a week as the pace that spares muscle [6], so this is the careful end of it. In a trial of athletes who trained hard and ate plenty of protein, losing at about 0.7% a week preserved and even built muscle, while losing twice as fast did not [7]. Leaner people tend to do better at the slower end of that range; people carrying more fat often tolerate the faster end. Cutting harder rarely speeds real fat loss in the evidence; it mostly costs muscle and makes the diet harder to sustain.

How much protein do you need while losing weight?

Protein is what keeps the weight you lose coming off as fat, not muscle, and how much you need depends on your goal and on whether you train. For muscle gain, meta-analyses place the point of diminishing returns near 1.6 g per kg, with little extra benefit beyond about 2.2 g per kg [4, 15]; a sports-nutrition consensus puts the useful range for active people at 1.4 to 2.0 g per kg [3]. The same 1.6 to 2.2 g per kg applies to fat loss when you train at least twice a week, and reviews of lean dieters who train go higher still, to 2.3 to 3.1 g per kg of fat-free mass [5]. If you cut without training, 1.2 to 1.6 g per kg is the range the evidence supports [24, 25]. For maintenance the tool uses 0.8 to 1.4 g per kg under 50, 0.8 to 1.2 from 50 to 64 and 1.0 to 1.5 from 65 [18, 25, 26], the same bands as our protein calculator. Each range is applied to a reference weight (your height at a healthy BMI, nudged a quarter of the way back toward your actual weight, and never above your actual weight) rather than raw bodyweight, so it isn't overstated if you carry extra fat. The 1.6 to 2.2 band is published per kg of total body mass, so a lean-mass-only basis would under-dose anyone carrying extra fat. If you enter a measured body-fat % we use whichever is higher, the reference weight or your lean mass, so measuring can only move the target up. For a more detailed breakdown, our protein calculator covers the same ground. It picks its basis differently though: total bodyweight for most people, an adjusted weight once body fat is high, and lean mass for trained lifters in a fat-loss phase, so its number can differ from the one here.

Protein calculator

The formula, in the open

Your resting metabolism uses the Mifflin-St Jeor equation [1]. For men: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women: the same, minus 161. Maintenance is then built additively rather than from a single multiplier: resting metabolism × a baseline activity level for your job (1.25 desk, 1.45 mixed, 1.6 on your feet, 1.8 manual labour) [18], plus the calories your planned training burns, counted from its MET value (about 3 for easy, 4.5 for moderate and 8 for hard sessions [19]) net of rest so the resting hours are not paid for twice. The older one-dropdown scale of 1.2 to 1.9 overstates a desk worker who trains hard and understates someone who moves all day and never trains. We use Mifflin-St Jeor rather than the older Harris-Benedict (1919) because it is more accurate for today's bodies [2]. If you have cross-checked elsewhere and got a higher number, that older formula is usually why. Enter a measured body-fat % (DEXA or calipers) and we switch to Katch-McArdle instead: 370 + 21.6 × lean mass [20]. Picking a figure by eye keeps Mifflin-St Jeor.

Mifflin-St Jeor vs. Harris-Benedict vs. Katch-McArdle: which formula is most accurate?

Mifflin-St Jeor (1990) is the default here because validation work rates it the most reliable of the common equations for healthy adults, predicting measured resting metabolism within about 10% for the largest share of people [2]. Harris-Benedict (1919, revised 1984) was built on a small, century-old sample and tends to overestimate for today's bodies by roughly 5%, which is why other calculators often hand you a higher number. Katch-McArdle works from lean body mass instead of total weight [20], so it can beat both for very lean or very muscular people, but only when the body-fat percentage you feed it is trustworthy (DEXA or calipers, not a glance in the mirror). Rule of thumb: without a reliable body-fat measurement use Mifflin-St Jeor; with one, Katch-McArdle.

What is the difference between BMR, maintenance calories and TDEE?

Your resting metabolic rate (BMR, or basal metabolic rate) is what your body burns at complete rest. Your activity burn is everything on top: walking, training, fidgeting, digesting. Maintenance, also called total daily energy expenditure (TDEE), is the two added together: BMR × a baseline activity level, plus your training burn. Eat around maintenance to hold your weight, below it to lose fat, above it to build muscle. The activity side is the biggest lever and the biggest source of error, which is why this tool splits it in two: a baseline factor for how much your job moves you, and your planned training counted separately on top.

How this calculator works

6 quick inputs, 3 useful numbers. Here is what happens under the hood.

  1. 1You enter your sex, age, height, weight, activity level, and goal.
  2. 2We estimate your resting metabolism with the Mifflin-St Jeor equation [1], among the best-validated resting-energy formulas for healthy adults [2].
  3. 3We multiply that by a baseline factor for how much your job moves you, then add the calories your planned training burns on top. The sum is your maintenance, the total you burn on an average day.
  4. 4For fat loss we subtract a moderate deficit (about 300 to 500 kcal, roughly 0.3 to 0.6% of bodyweight a week for most adults) and show the estimated weekly loss. Sports-nutrition guidance names 0.5 to 1.0% a week as a muscle-sparing pace [6], so this sits at or below it.
  5. 5The tool picks a protein range for your goal: 1.6 to 2.2 g per kg for muscle gain and for fat loss with regular training, where muscle gains level off in meta-analyses [4, 15]; 1.2 to 1.6 g per kg for fat loss without training [24, 25]; and 0.8 to 1.4 g per kg for maintenance, adjusted for age [18, 26].

These are estimates, so treat them that way

Every formula here is a population average, and your real burn can sit above or below it, especially at the extremes of body size and in older adults. The weekly-loss figures use a simple rule of thumb (about 7,700 kcal per kg of fat); real loss is slower and tapers as your body adapts; a maintained 500 kcal/day cut delivers only about half its 'expected' loss in the first year [13], so treat the weekly number as a 4-to-8-week guide, not a promise [10, 11]. The same linear rule is used on the surplus side, where it is rougher still: gained weight is a mix of fat and lean tissue with different energy densities, and controlled overfeeding shows the real cost per kg gained runs higher than 7,700 kcal [23]. For multi-month projections, the NIH Body Weight Planner models the slowdown. Metabolism may also adapt after weight loss, with resting energy expenditure dropping by somewhat more than your smaller body explains, though how large and lasting that is remains debated [8]; and after about 60, estimates get less precise as cellular metabolism declines independent of muscle and movement [14]. The remedy isn't a fancier equation, it's feedback. In practice, people treat the number as a hypothesis: holding intake near the estimate for 2 to 3 weeks, watching the weekly-average weight, and revising by roughly 100 to 200 kcal if the trend is off. A dietitian can help you do this safely.

Frequently asked questions

How accurate is a calorie calculator?

It gives a solid starting estimate, but it is still an estimate. The resting-metabolism part is usually within about 10% for most healthy adults; how you rate your activity adds more uncertainty on top. The Mifflin-St Jeor equation it uses [1] is among the best-validated for resting metabolism [2], though it is less accurate at the extremes of body size and less well validated in older adults. Your true burn also depends on genetics, muscle mass, and daily movement, so treat maintenance as a starting point and adjust based on your weekly results.

What is the difference between BMR and maintenance calories?

BMR (basal metabolic rate) is what your body burns at complete rest just to keep you alive. Maintenance, or TDEE, is BMR plus everything else you do: walking, fidgeting, working out, digesting food. We multiply BMR by a baseline activity level for your job and add your training burn separately, which gives maintenance, the number you eat around to hold your weight.

How big a calorie deficit should I use to lose fat?

A moderate one, about 300 to 500 kcal a day. By the 7,700 kcal per kg rule that is roughly 0.3 to 0.6% of bodyweight a week for most adults, at or under the 0.5 to 1.0% a week that sports-nutrition guidance names as muscle-sparing [6]. Losing slower protects muscle: in one trial, the slower rate built muscle (alongside strength training) while the faster rate did not [7]. We never suggest eating below your resting metabolism.

How much protein should I eat while losing weight?

It depends on whether you train. About 1.6 to 2.2 g per kg a day if you train at least twice a week [4]; a sports-nutrition consensus puts the range for active people at 1.4 to 2.0 g per kg [3], and reviews of lean dieters go to 2.3 to 3.1 g per kg of fat-free mass [5]. If you diet without training, 1.2 to 1.6 g per kg is the range supported by the evidence [24, 25]. This tool doses the range on a reference weight rather than raw bodyweight: your height at a BMI of 22, moved a quarter of the way back toward your actual weight and never above it. If you enter a measured body fat and your lean mass comes out higher, we use that instead. So the target isn't overstated if you carry extra fat.

Why does my weight loss slow down even if I keep eating the same?

2 things compound: maintenance drops as you get smaller, and resting metabolism can fall by somewhat more than your size predicts (adaptive thermogenesis), though its size is debated [8]. People typically recalculate as their weight changes and keep protein and resistance training high to protect muscle; our weight-loss plateau guide covers the evidence.

Is the 7,700 kcal per kg (3,500 kcal per pound) weight-loss rule accurate?

It is a handy short-term guide but it overestimates real loss over months. A maintained 500 kcal/day deficit delivers only about half its 'expected' loss in the first year as your body adapts [13]. Use the weekly figure as a 4-to-8-week guide, not a 6-month promise; for longer projections the NIH Body Weight Planner models the slowdown.

Which formula is most accurate: Mifflin-St Jeor or Harris-Benedict?

For most healthy adults Mifflin-St Jeor (1990) is the more accurate of the common equations, landing within about 10% of measured resting metabolism [2]. The older Harris-Benedict (1919) tends to run higher, which is why other calculators may show you a larger number. If you have a measured body-fat % (DEXA or calipers), Katch-McArdle can be better still for very lean or muscular people because it works from lean mass.

Does my menstrual cycle or menopause change my calorie needs?

Only a little. Pooled studies find a small, possibly negligible rise in resting metabolism in the second half of the cycle [22], which sits inside this tool's margin, so we don't add a cycle adjustment. Menopause needs no separate factor either: the decline tracks age, height and weight, which are already inputs [14]. Pregnancy (about +250 kcal in the second and +500 in the third trimester) and breastfeeding (about +500) do add real needs under medical guidance, and are outside this tool's scope.

What is a safe minimum number of calories per day?

This tool never suggests eating below your resting metabolism, and holds a lower bound of 1,200 kcal for women and 1,500 for men [12]. If your maintenance is already below that, we hold you at maintenance instead, so the tool never suggests a deficit. Diets below about 800 kcal a day are clinical very-low-calorie diets that need medical supervision (NICE NG246, 2025). If hitting a number ever feels distressing, please speak to a doctor.

Why does every calorie calculator show me a different number?

3 reasons: different formulas (Harris-Benedict runs about 5% higher than Mifflin-St Jeor), different activity multipliers (many tools compress your whole life into one vague dropdown, this one separates your job baseline from your training), and rounding. Differences of 100 to 300 kcal between tools are normal, and no formula beats the roughly ±10% real-world spread anyway [2]. Pick one estimate, hold it for two to three weeks, and let your weekly-average weight tell you whether to adjust.

How many calories does the average person need a day?

Food labels use a single 2,000 kcal reference for an average adult, but real maintenance runs roughly 1,600 to 2,400 kcal for adult women and 2,000 to 3,000 kcal for adult men depending on age, size and movement (Dietary Guidelines for Americans 2020 to 2025). A small office worker and a tall nurse can differ by 1,000 kcal a day, which is why this calculator asks for your details instead of assuming an average.

Should I eat back the calories I burn from exercise?

With this calculator, no: your training is already averaged into your daily target, that is what the exercise inputs do. Eating workout calories back on top would count them twice. Treat watch and machine readouts with suspicion too; planned workouts often displace other daily movement, so the true net extra is smaller than the display suggests.

Sources

The formula and the calorie and protein targets are drawn from these peer-reviewed sources.

  1. 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. The American Journal of Clinical Nutrition. doi:10.1093/ajcn/51.2.241
  2. 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. doi:10.1016/j.jada.2005.02.005
  3. Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. doi:10.1186/s12970-017-0177-8
  4. Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, 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. doi:10.1136/bjsports-2017-097608
  5. Helms ER, Zinn C, Rowlands DS, Brown SR (2014). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. International Journal of Sport Nutrition and Exercise Metabolism. doi:10.1123/ijsnem.2013-0054
  6. Aragon AA, Schoenfeld BJ, Wildman R, Kleiner S, VanDusseldorp T, et al. (2017). International Society of Sports Nutrition position stand: diets and body composition. Journal of the International Society of Sports Nutrition. doi:10.1186/s12970-017-0174-y
  7. Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J (2011). Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. International Journal of Sport Nutrition and Exercise Metabolism. doi:10.1123/ijsnem.21.2.97
  8. Leibel RL, Rosenbaum M, Hirsch J (1995). Changes in energy expenditure resulting from altered body weight. New England Journal of Medicine. doi:10.1056/NEJM199503093321001
  9. Paluch AE, Bajpai S, Bassett DR, Carnethon MR, Ekelund U, et al. (2022). Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. The Lancet Public Health. doi:10.1016/S2468-2667(21)00302-9
  10. Wishnofsky M (1958). Caloric equivalents of gained or lost weight. The American Journal of Clinical Nutrition. doi:10.1093/ajcn/6.5.542
  11. Hall KD, Chow CC (2013). Why is the 3500 kcal per pound weight loss rule wrong?. International Journal of Obesity. doi:10.1038/ijo.2013.112
  12. Jensen MD, Ryan DH, Apovian CM, Ard JD, Comuzzie AG, et al. (2014). 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Circulation. doi:10.1161/01.cir.0000437739.71477.ee
  13. Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet. doi:10.1016/S0140-6736(11)60812-X
  14. Pontzer H, Yamada Y, Sagayama H, Ainslie PN, Andersen LF, et al. (2021). Daily energy expenditure through the human life course. Science. doi:10.1126/science.abe5017
  15. Nunes EA, Colenso-Semple L, McKellar SR, Yau T, Ali MU, et al. (2022). Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults. Journal of Cachexia, Sarcopenia and Muscle. doi:10.1002/jcsm.12922
  16. Murphy C, Koehler K (2022). Energy deficiency impairs resistance training gains in lean mass but not strength: A meta-analysis and meta-regression. Scandinavian Journal of Medicine & Science in Sports. doi:10.1111/sms.14075
  17. Barakat C, Pearson J, Escalante G, Campbell B, De Souza EO (2020). Body Recomposition: Can Trained Individuals Build Muscle and Lose Fat at the Same Time?. Strength and Conditioning Journal. doi:10.1519/SSC.0000000000000584
  18. Institute of Medicine, Food and Nutrition Board (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press. doi:10.17226/10490
  19. Herrmann SD, Willis EA, Ainsworth BE, Barreira TV, Hastert M, 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. doi:10.1016/j.jshs.2023.10.010
  20. Cunningham JJ (1991). Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation. The American Journal of Clinical Nutrition. doi:10.1093/ajcn/54.6.963
  21. Byrne NM, Hills AP, Hunter GR, Weinsier RL, Schutz Y (2005). Metabolic equivalent: one size does not fit all. Journal of Applied Physiology. doi:10.1152/japplphysiol.00023.2004
  22. Benton MJ, Hutchins AM, Dawes JJ (2020). Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis. PLOS ONE. doi:10.1371/journal.pone.0236025
  23. Bouchard C, Tremblay A, Després JP, Nadeau A, Lupien PJ, et al. (1990). The response to long-term overfeeding in identical twins. New England Journal of Medicine. doi:10.1056/NEJM199005243222101
  24. Leidy HJ, Clifton PM, Astrup A, et al. (2015). The role of protein in weight loss and maintenance. American Journal of Clinical Nutrition. doi:10.3945/ajcn.114.084038
  25. Phillips SM, Chevalier S, Leidy HJ (2016). Protein 'requirements' beyond the RDA: implications for optimizing health. Applied Physiology, Nutrition, and Metabolism. doi:10.1139/apnm-2015-0550
  26. Bauer J, Biolo G, Cederholm T, et al. (PROT-AGE Study Group) (2013). Evidence-based recommendations for optimal dietary protein intake in older people. Journal of the American Medical Directors Association. doi:10.1016/j.jamda.2013.05.021

Stuck on a plateau, or losing muscle instead of fat?

Knowing your numbers is step one. Our guide shows what the research says about breaking a stall, keeping muscle, and not rebounding.

Read the plateau guide Protein calculator