Calorie Calculator: calories to maintain or lose weight

Key takeaways

• Mifflin-St Jeor predicted resting metabolism within 10% for more people than other common equations, but errors for individuals remain.^[2]
• Guidelines describe weight-loss targets as a 500 to 750 calorie daily deficit, or about 1,200-1,500 calories a day for women and 1,500-1,800 for men.^[3]
• The "3,500 calories per pound" rule overpredicts long-term loss because the body needs less energy as weight falls.^[5]
• At the same calories, higher-protein diets led to slightly more fat loss and less lean-mass loss in a meta-analysis of 24 trials.^[6]

In short: This calorie calculator estimates how many calories your body uses in a day (your maintenance calories) and shows a few gentle weight-loss options below that. It uses the Mifflin-St Jeor equation, which a systematic review found to be the most reliable of the common formulas, but any equation can be off by 10% or more for one person. Treat the result as a first guess that you adjust from real life.

Calorie calculator

Units

US (lb, ft, in)Metric (kg, cm)

Sex (the equations use it)

FemaleMale

Ageyears

Height

ftin

Current weightlb

Activity levelSedentary: little or no exerciseLightly active: light exercise 1-3 days a weekModerately active: exercise 3-5 days a weekVery active: hard exercise 6-7 days a weekExtra active: hard daily training or a physical job

Calculate calories

Fill in the fields and press the button to see your result.

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Educational estimate, not medical advice. Talk with a healthcare professional before changing how you eat, move or take medicines.

How this works

First we estimate the energy your body uses at rest with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then + 5 for men or − 161 for women.

That is multiplied by an activity factor (1.2 sedentary up to 1.9 extra active) to estimate maintenance calories.

The weight-loss options subtract 250, 500 or 750 calories a day. An option is hidden when it would mean losing more than about 1% of body weight a week, or eating under 1,200 calories (women) or 1,500 (men) without a clinician.

Limits

• Equations predict the average person of your size, age and sex. Any one person can be 10% or more above or below.
• Built for adults 18 and older. Teens are still growing, so no targets are shown for anyone under 18.
• Weight loss slows as you lose weight, because a smaller body uses less energy. A fixed deficit does not keep producing the same loss.
• Not for pregnancy, breastfeeding or medical conditions that change metabolism; ask your clinician.

Sources

1. Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990;51:241-247
2. Dietary Guidelines for Americans 2020-2025 (AMDR and calorie guidance)
3. NHLBI: Clinical guidelines on overweight and obesity (low-calorie diet ranges)

Reading your result

You get two kinds of numbers. Maintenance is the estimated amount of energy that would keep your weight about where it is today, given the activity level you picked. The weight-loss options are that number minus a set daily deficit. A smaller deficit means slower loss that is usually easier to live with; a larger one means faster early loss but more hunger and more chance of losing muscle.

Clinical guidelines from the American Heart Association, the American College of Cardiology and The Obesity Society describe two common ways programs set a target: an energy deficit of about 500 or 750 calories a day below what a person needs, or a fixed intake, usually 1,200 to 1,500 calories a day for women and 1,500 to 1,800 for men, adjusted for body weight and activity. The calculator follows the first approach and hides any option that would drop below those lower limits, because eating less than that without supervision makes it hard to get enough protein, vitamins and minerals.

Women1,200 kcal–1,500 kcal

Men1,500 kcal–1,800 kcal

0 kcal900 kcal1,800 kcal

Fixed daily calorie targets often used in guideline programs

Item	Low	High
Women	1,200 kcal	1,500 kcal
Men	1,500 kcal	1,800 kcal

Guideline ranges, adjusted for body weight and activity in real programs; not a personal target.

Source: 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults (checked on October 6, 2026)

How close is the estimate?

Mifflin-St Jeor was published in 1990 from measurements of healthy adults. When dietitians compared the common equations against measured resting metabolism, Mifflin-St Jeor came closest, predicting within 10% for more people, with and without obesity, than the other formulas. The same review noted that older adults and ethnic minorities living in the U.S. were underrepresented in the research, so the estimate may fit some groups less well.

The activity setting is the other big source of error, so if you are unsure between two levels, start with the lower one. Wrist-worn fitness devices are not a reliable check: in a Stanford study of seven popular devices, none estimated calories burned with an error below 20%. Our calories burned calculator gives a more cautious estimate for specific activities.

Test it for two to three weeks, then adjust

1. Pick one option and track what you eat as honestly as you can. An app or a simple notebook both work.
2. Weigh yourself a few times a week at the same time of day and look at the average, not single days. Water, salt and food in your gut move the scale from day to day. Our weight tracker shows the trend and keeps your entries on your device.
3. Compare the trend with the plan. If your weight is steady while you eat your “maintenance” number, that number is right for you. If you are losing faster or slower than expected, move your target up or down a little.

Why the same number stops working

As you lose weight, your body needs less energy: there is less of you to maintain and move, and the body adapts. Researchers at the National Institutes of Health showed that the old rule of “3,500 calories per pound” overpredicts how much people lose over time. So the weight-loss option you pick today will produce slower loss in a few months. Re-run the calculator after every 10 pounds or so, and expect plateaus; our guide to the weight-loss plateau explains what to do. To see how the pace changes over months, use the weight-loss timeline calculator.

Calorie, TDEE or weight-loss calculator: which one?

• This calorie calculator answers “how much should I eat to maintain or lose weight?” with ready-made options.
• The TDEE calculator shows your total daily energy use at every activity level and can use your body fat percentage, if you know it.
• The weight-loss calculator answers “when could I reach my goal?” with a range of dates.

Making the calories count

Calories decide whether you lose weight; food choices decide how it feels. In a meta-analysis of 24 trials, people on calorie-reduced diets that were higher in protein lost a little more fat and kept a little more lean mass than people on standard-protein diets with the same calories. In three of the five trials that measured it, the higher-protein diet also left people feeling fuller. Use the protein calculator for a daily range and the macro calculator to split your calories into protein, carbs and fat. Our guide to the calorie deficit covers the practical side in more depth.

When to get personal advice

Talk with a doctor or registered dietitian before cutting calories if you are pregnant or breastfeeding, have diabetes or take medicine that lowers blood sugar, have kidney disease, have a history of an eating disorder, or are under 18. The same goes for anyone thinking about a very low-calorie plan: guidelines say those should only be used with medical monitoring. Our how to lose weight hub shows the wider picture.

Questions to ask a professional

• What daily calorie range makes sense for me, given my health and medicines?
• How fast should I aim to lose weight, and how will we know if it is too fast?
• Could a registered dietitian help me plan meals around this number?
• Do any of my conditions or medicines change how I should cut calories?

Frequently asked questions

How many calories should I eat to lose weight?

Start from your estimated maintenance calories and eat somewhat less; guidelines describe deficits of about 500 to 750 calories a day. Track your weight for two to three weeks and adjust. A doctor or registered dietitian can set a target that fits your health.

Is 1,200 calories a day safe?

Guidelines use about 1,200 to 1,500 calories a day as a common weight-loss range for women, and 1,500 to 1,800 for men. Going lower should only happen with medical supervision. Whether a number is right for you depends on your size, activity and health.

Why does the calculator give me a different number than my fitness watch?

Each uses a different method. In one lab study, none of seven popular wrist devices estimated calories burned with an error below 20%. Neither number is exact. The best test is your own weight trend over a few weeks.

Should I eat back the calories I burn exercising?

The activity level you chose already includes your usual exercise, so there is no need to add it again. If you add extra exercise, eating back a part of it is a reasonable middle ground while you watch your weight trend.

Does this work during pregnancy or breastfeeding?

No. Energy needs change during pregnancy and breastfeeding, and weight loss is not usually the goal. Ask your obstetric clinician or a registered dietitian.

References

1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990. doi:10.1093/ajcn/51.2.241 · PMID 2305711 (accessed October 7, 2026) Other
2. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, 2005. doi:10.1016/j.jada.2005.02.005 · PMID 15883556 (accessed October 6, 2026) Review
3. Jensen MD, Ryan DH, Apovian CM, et al.. 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Circulation, 2014. doi:10.1161/01.cir.0000437739.71477.ee · PMID 24222017 (accessed October 7, 2026) Guideline
4. Hall KD, Sacks G, Chandramohan D, et al.. Quantification of the effect of energy imbalance on bodyweight. The Lancet, 2011. doi:10.1016/S0140-6736(11)60812-X · PMID 21872751 (accessed October 7, 2026) Other
5. Thomas DM, Martin CK, Lettieri S, et al.. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. International Journal of Obesity, 2013. doi:10.1038/ijo.2013.51 · PMID 23628852 (accessed October 6, 2026) Other
6. Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. American Journal of Clinical Nutrition, 2012. doi:10.3945/ajcn.112.044321 · PMID 23097268 (accessed October 7, 2026) Meta-analysis
7. Shcherbina A, Mattsson CM, Waggott D, et al.. Accuracy in Wrist-Worn, Sensor-Based Measurements of Heart Rate and Energy Expenditure in a Diverse Cohort. Journal of Personalized Medicine, 2017. doi:10.3390/jpm7020003 · PMID 28538708 (accessed October 7, 2026) Other

Facts checked on October 6, 2026

Educational information, not medical advice. Talk with a qualified healthcare professional about your own situation. In an emergency call 911.