How many calories should I eat a day?

Which daily calorie number are you looking for?

If you want to maintain your weight, the starting question is how much energy your body uses across a whole day. That includes more than exercise: a desk day still has energy costs, and a shift spent moving has different demands from a day spent sitting.

The on-page tool estimates resting energy with Mifflin–St Jeor, then multiplies it by an activity assumption. Read the daily maintenance output, not the resting figure. It does not decide your goal or save a target to IZeat.

Three numbers answer three different questions:

You can eat 2,100 calories while a calculator estimates maintenance at 2,300. That does not make either value a direct measurement of your body's energy use. The two numbers also do not establish an appropriate long-term intake.

The FDA explains that 2,000 calories is a general guide. Your needs can be higher or lower. A food label helps you understand a portion; it cannot personalize a daily target.

How can you get a useful starting estimate?

Prepare your current age, height and weight, with the units written down. Describe a normal week of movement, work and exercise rather than your most active day. Many tools also ask for sex because it is a variable in the equation they use; the result remains an estimate, including when those categories are an imperfect fit for an individual.

For a personal starting number, use the maintenance calculator in the first section. Enter your measurements with the correct units and the equation’s sex variable, choose the activity assumption that describes your representative routine, then calculate. Read the estimated daily maintenance and keep the inputs and multiplier with it. If two assumptions seem plausible, compare their results without treating either as a measurement.

For a comparison using a different model, the Mayo Clinic calorie calculator supplies an external route:

1. Choose US or metric units, then enter your age, height, weight and the equation’s sex category.
2. Select the activity description closest to your ordinary routine. Read the descriptions rather than choosing the most active category because you exercise occasionally.
3. Calculate, then read the daily maintenance estimate. Compare the alternative activity results if your routine sits between descriptions.
4. Keep the inputs and chosen activity description with the result. You now have a starting maintenance number, not a personalized loss target.

You can also see the calculation with a simple example. A hypothetical adult using the male Mifflin–St Jeor equation at age 35, 80 kg and 180 cm has an estimated resting expenditure of 1,755 kcal/day. An explicitly assumed multiplier of 1.4 produces about 2,450 kcal/day. That is a worked arithmetic example, not a Mayo result or an activity category assigned to you. The original equation estimates resting energy; selecting the daily activity assumption is a separate step.

For a worked explanation of resting energy, activity and units, read the calorie calculation guide. The calculator on this page uses the explained Mifflin method. Mayo provides a separate external route based on its own method and activity descriptions.

Keep a short record of your inputs beside the result. “About 2,300 kcal/day, based on my current weight and mostly seated work” is more useful than an isolated 2,300. When work, training or body weight changes, you can identify which assumption needs updating.

What do you do with the result?

If maintenance is your goal, treat the result as a starting estimate for your current circumstances. It gives you something to compare with a complete food record and the direction of your weight over time.

If your goal is weight loss, maintenance is only the starting point. A loss target also needs a suitable energy reduction, a workable eating pattern and a review plan. See how many calories to eat to lose weight. The existing maintenance, deficit and target explanation shows how those numbers relate.

If your goal is weight gain or demanding sports performance, the maintenance estimate still does not set the whole plan. Food quality, training demands and individual circumstances matter alongside energy. Use appropriate professional guidance when a generic estimate cannot answer the decision you are making.

Consider an illustrative maintenance estimate of 2,300 kcal/day. A complete diary averaging roughly that amount while body weight is broadly stable is compatible with the estimate. Record the dates, food totals and body-weight observations together so you can compare the same period. This does not prove that 2,300 is an exact requirement. If the diary contains only lunches and dinners, its average cannot support that comparison at all.

How do you check whether the estimate fits your routine?

Look at the inputs before changing the output. Did you enter pounds as kilograms? Does your activity category include your workday, or only workouts? Has your routine changed since you calculated the estimate?

Then inspect the food record. Include drinks, cooking fats and meals away from home, and distinguish a remembered portion from a weighed one. The intake guide explains how to total what you actually recorded without treating an incomplete day as a full day.

Finally, review your goal and observations together. A single food total is not enough to validate maintenance. Keep weight observations separately, with their dates, and use a consistent approach so the comparison is interpretable. This is a practical review method, not an automatic formula for adjusting your diet.

IZeat is the five-star chef calorie tracker that suggests satisfying, great-tasting meals, so you enjoy every calorie you have left. Once connected, tell your assistant what you ate, provide quantities and sources when needed, and ask for the day's recorded total. IZeat stores the meals and target; the assistant explains the record. IZeat does not measure expenditure or store a weight trend, and its recorded-day average cannot certify that every meal was entered.

For the complete logging method, continue with how to track calories.

When is a general calculator the wrong starting point?

The NIDDK Body Weight Planner is intended for adults and excludes pregnancy and breastfeeding. A general estimate also deserves individual review when medical treatment or unusual training demands affect the plan. Mayo notes limitations for competitive athletes and metabolic disease.

A clinician or registered dietitian who knows your circumstances can help choose an appropriate method. A more detailed form does not, by itself, make the output appropriate for every reader.

Sources and method

Method: the on-page calculator uses Mifflin–St Jeor for resting energy and a selected activity multiplier for estimated maintenance. The multiplier is a planning assumption separate from the original resting equation. This maintenance view does not apply a reduction; the separate weight-loss page estimates a starting intake using a visible, editable reference reduction. Results are estimates, not measured energy use. Sources and external tool instructions were checked on 4 October 2026. The examples are declared arithmetic, not submitted external tool results or clinical validation.

• FDA: Understanding the Nutrition Facts Label.
• Mayo Clinic: Calorie calculator.
• NIDDK: About the Body Weight Planner.
• Mifflin et al., 1990: resting-energy prediction.