How Many Calories Should I Eat? A Plain-English Guide

How many calories should I eat? Most adults need roughly 1,600 to 2,400 calories a day (women) or 2,000 to 3,000 (men) to maintain their weight, according to the most recent federal calorie-needs table. Where you land in that range depends on your body, your age, how much you move, and what you’re trying to do. There’s no single right number, but there is a clear way to get a good first estimate, and an even better way to correct it once you have a few weeks of real data.

This guide is for general education and is written for adults. If you’re pregnant or breastfeeding, have diabetes, have a history of disordered eating, or are under 18, read the section on who should get personal advice first (just after the minimums) before setting any target.

This guide walks through both. You’ll see typical ranges, work out a personal estimate with the equation a systematic review found most reliable, learn how to set a sensible target for losing, maintaining, or gaining weight, and see the minimums you shouldn’t go below without a clinician. Every number here is information, not a grade. A higher target isn’t a failure and a lower one isn’t an achievement.

How many calories should you eat a day? Typical ranges

The most detailed federal estimates come from the estimated calorie-needs table in the previous, 2020–2025 edition of the Dietary Guidelines for Americans (Appendix 2). It estimated that adults need roughly 1,600 to 2,400 calories a day for women and 2,000 to 3,000 for men to maintain their weight, and that needs generally fall with age because basal metabolic rate declines.

The current 2025–2030 edition, released in January 2026, doesn’t include a calorie-needs table of its own. It says the calories you need depend on your age, sex, height, weight, and level of physical activity, and its daily servings guide points to the USDA’s DRI Calculator for individual estimates.

Here’s a slice of the 2020–2025 table for selected age groups:

Age	Women: sedentary	Women: moderately active	Women: active	Men: sedentary	Men: moderately active	Men: active
21–25	2,000	2,200	2,400	2,400	2,800	3,000
31–35	1,800	2,000	2,200	2,400	2,600	3,000
41–45	1,800	2,000	2,200	2,200	2,600	2,800
51–55	1,600	1,800	2,200	2,200	2,400	2,800
61–65	1,600	1,800	2,000	2,000	2,400	2,600

The activity levels are defined in walking terms. "Sedentary" means only the activity of everyday independent living. "Moderately active" adds the equivalent of walking about 1.5 to 3 miles a day at 3 to 4 miles per hour. "Active" means walking more than 3 miles a day at that pace.

Two caveats matter a lot. First, the table is built for a reference man who is 5 feet 10 inches and 154 pounds and a reference woman who is 5 feet 4 inches and 126 pounds. If you’re taller, shorter, heavier, or lighter, your number will differ. Second, the Guidelines called these figures "only estimates." They’re a sanity check, not a prescription.

To get closer to your own number, you need to understand where it comes from.

Where your calorie number comes from

Your body burns energy in three main ways, as physiologist Klaas Westerterp lays out in a review of energy expenditure:

1. Basal metabolic rate (BMR): the energy that keeps you alive at rest. It’s usually the largest part of the day’s total.
2. The thermic effect of food: the energy used to digest and process what you eat. On a mixed diet it’s about 5% to 15% of daily energy expenditure.
3. Physical activity: everything from workouts to walking to the kitchen.

Add them together and you get your total daily energy expenditure (TDEE). That’s the number of calories that would keep your weight roughly stable, also called your maintenance calories. If BMR and TDEE are new terms, our explainer on BMR vs TDEE goes deeper.

Work out your own estimate in three steps

Here’s the process, using an example person: a 35-year-old woman who is 5 feet 6 inches (168 cm), weighs 170 pounds (77 kg), and walks most days but doesn’t train hard. The full step-by-step arithmetic for her, and for a second example person, is in BMR vs TDEE.

Step 1: Estimate BMR with Mifflin-St Jeor

The Mifflin-St Jeor equation was published in 1990 from measurements of 498 healthy adults. It’s the equation a systematic review for the American Dietetic Association found most reliable: it predicted resting metabolic rate within 10% of the measured value in more people than the other common equations it tested.

It uses metric units:

• Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
• Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

For our example woman, that comes to about 1,484 calories a day.

Step 2: Multiply by an activity factor

Calculators turn BMR into TDEE by multiplying by an activity factor. Most use a version of this scale:

Activity level	Multiplier
Sedentary (desk job, little exercise)	1.2
Lightly active (light exercise or walking a few days a week)	1.375
Moderately active (exercise most days)	1.55
Very active (hard exercise or a physical job)	1.725

These multipliers are a convention, not a measurement, and they run on the cautious side. Researchers measure the same idea as a "physical activity level," the ratio of total to basal energy use. The National Academies’ 2023 energy report describes typical adult values from about 1.4 for inactive people to about 2.05 for very active people. Its "inactive" example already includes about 30 minutes of walking and roughly 90 minutes of light activity like housework a day, yet it sits well above the calculator’s 1.2 for "sedentary." The scales aren’t a perfect like-for-like comparison, but measured activity in real adults tends to run higher than the conventions suggest. The same report calls choosing the right category "perhaps the most challenging aspect" of estimating needs, which is one more reason to check your estimate against your trend.

Our example is lightly active:

• 1,484 × 1.375 = about 2,040 calories a day

That’s in the same ballpark as the 2020–2025 table’s 1,800 to 2,000 for a sedentary to moderately active woman her age, and a little higher because she’s heavier than the 126-pound reference woman. A 40-year-old, 200-pound, moderately active man works out to about 2,830, also a little above his table value of 2,600 for the same reason.

Step 3: Adjust for your goal

• To maintain your weight, eat around your TDEE. Our guide to finding your maintenance calories shows how to turn this estimate into a number you’ve confirmed.
• To lose weight, eat somewhat less than your TDEE. That gap is a calorie deficit.
• To gain weight, eat somewhat more. A modest surplus is the usual approach, and many people pair it with strength training.

Setting a target to lose, maintain, or gain

If weight loss is your goal, a modest deficit is usually the most livable. The CDC notes that people who lose weight at a gradual, steady pace of about 1 to 2 pounds a week are more likely to keep it off, and that range is an upper limit, not a quota. For our example woman, a 400-calorie deficit means:

• 2,040 − 400 = about 1,640 calories a day

That leaves room for normal meals. Our guide to calorie deficits covers how to size one for your body, including why bigger isn’t better.

You may have heard that a pound of fat is 3,500 calories, so cutting 500 a day loses a pound a week. Research shows that rule overestimates weight loss even within the first couple of months, and the gap grows over time; we cover the evidence in how many calories to lose a pound a week. For a realistic long-term projection, the NIH’s free Body Weight Planner uses a dynamic model developed by Kevin Hall and colleagues.

The minimums: why lower isn’t better

It’s tempting to think the smaller the number, the faster the progress. That’s not how it works, and it isn’t safe.

Harvard Health advises that calorie intake should not fall below 1,200 a day for women or 1,500 a day for men except under the supervision of a health professional, because eating too little can deprive you of needed nutrients. Very-low-calorie diets, around 800 calories a day or less, are used only under a health care professional’s supervision.

A few practical points follow from this:

• A minimum is a floor, not a goal. Most adults need well above it.
• If your math lands below the floor, the plan needs to change, not your body. A smaller deficit or more activity is the safer adjustment. For our example woman, a 1,000-calorie deficit would mean about 1,040 calories a day, below the floor.
• Feeling unwell is information. Ongoing dizziness, exhaustion, or a preoccupation with food are reasons to eat more and talk to a doctor.

This is why Lettuceburn’s plan has a hard floor of 1,200 calories (1,500 for men), never sets a deficit larger than 25% of your estimated TDEE, and has streaks and rewards built so they never reward eating less.

Who should get personal advice first

General formulas aren’t designed for everyone. Please talk to a doctor or registered dietitian before setting a calorie target if any of these apply:

• Pregnancy or breastfeeding. The 2020–2025 Dietary Guidelines estimated that needs rise by about 340 calories a day in the second trimester and 452 in the third, and by 330 to 400 a day while breastfeeding, and recommended following your health care provider’s guidance, since many factors change those needs. The NIH Body Weight Planner states it is not intended for pregnant or breastfeeding women.
• Diabetes. The NIDDK advises people with diabetes to work with their health care team on a meal plan, and notes some medicines, such as insulin, can cause low blood glucose if you skip or delay a meal.
• A history of disordered eating. The National Institute of Mental Health describes eating disorders as serious and potentially life-threatening, and treatable. If counting calories pulls you toward restriction, it’s okay to stop and reach out for support instead.
• Under 18. Teens are still growing, and their needs differ from adults’. The Body Weight Planner is designed for people 18 and older.
• Other medical conditions or medications that affect appetite, weight, or metabolism.

The systematic review that favored Mifflin-St Jeor also found that older adults and U.S. ethnic minorities were underrepresented in the studies behind the equations, so estimates may be less reliable for some groups.

Why your estimate will be off (and why that’s fine)

Every step above has some error:

• The formula. Mifflin-St Jeor is the most reliable common equation, but the same review found "noteworthy errors" when it’s applied to individuals.
• The activity factor. Picking between "lightly" and "moderately" active can move the result by a couple of hundred calories.
• Your food log. Portions are hard to judge by eye, and the National Academies’ report notes that underreporting is common in self-reported intake.

None of this means estimating is pointless. It means your first number is a starting hypothesis. The useful question isn’t "is this number perfect?" It’s "what happens when I eat around it for a few weeks?"

Let your weight trend correct the estimate

Your body is the most accurate calculator you have. If you log your food reasonably consistently and weigh yourself a few times a week, you can work backward: if your weight trend holds steady at a given intake, that intake is about your maintenance. If it drifts, the size of the drift tells you how far off the estimate was.

The catch is that daily scale readings bounce around. In one large study, weight rose on weekends and fell during the week, and stored carbohydrate is held with three to four parts water, so one salty or carb-heavy meal can move the scale overnight. Look at the trend over weeks, not single readings.

This back-calculation is often called adaptive TDEE. Our guide to adaptive TDEE explains the math and how to do it by hand or in an app.

Calories are one piece of the picture

Hitting a calorie number with mostly ultra-processed snacks feels different from hitting it with meals built around protein, fiber, and foods you enjoy. Once you have a calorie target, the next useful step is understanding what makes it up. Our guide to how to count macros covers protein, carbs, and fat.

And because any calorie target is only as good as your log, it’s worth knowing the strengths and limits of the tool you use. We dug into the research on how accurate AI calorie trackers are, including photo logging.

How Lettuceburn handles this

We built Lettuceburn to make this process practical without turning your plate into a scorecard:

• A personalized starting plan. A short onboarding quiz calculates your BMR with Mifflin-St Jeor, applies an activity factor and your chosen pace, and runs it through the safety floors above.
• Adaptive targets, on by default. Once you have enough logged days and weigh-ins, Lettuceburn re-estimates your real expenditure from your weight trend each week and nudges your target up or down by at most 150 calories at a time.
• Weekly insights on your calorie, protein, and weight trends, described in neutral language. Your weight going up is reported the same way as your weight going down.
• Fast logging, including photo scans you can edit before saving, so your data reflects what you ate.

All of this is free. Photo scans run on your own AI key (free forever) or on Pro; the plan, adaptive targets, and insights need no key at all, and your food log stays on your phone. See Lettuceburn’s full feature list or read how Lettuceburn works. The app is coming soon to iPhone and Android, and you can join the waitlist.

Read next in this guide

• What is a calorie deficit? How deficits work and how to set a sensible one.
• Maintenance calories: what they are and how to confirm yours.
• BMR vs TDEE: the two numbers behind every calorie calculator, with the full worked examples.
• How many calories to lose a pound a week: the 3,500-calorie rule and its limits.
• Adaptive TDEE: how your weight trend can correct your target.