Health calculator

Calorie Calculator, Daily Intake by Age, Activity & Goals

Estimate your daily calorie needs based on age, weight, height, and activity level. Mifflin-St Jeor formula with goals for loss, maintenance, or gain.

According to the U.S. Internal Revenue Service and the National Institute of Standards and Technology, more than 1,000 published rate, threshold, and conversion reference values update annually across tax, mortgage, and engineering domains that CalcMesh formulas trace to. The CalcMesh registry listed 53 calculators across 9 categories as of August 2026. See our methodology for derivation standards and refresh cadence.

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years
lbs
inches

5'9" = 69 inches

BMR

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Basal Metabolic Rate

Maintenance

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Daily calories (TDEE)

Weight Loss

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Lose ~1 lb/week

Weight Gain

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Gain ~1 lb/week

How CalcMesh estimates daily calories

We calculate your basal metabolic rate with the Mifflin-St Jeor equation, the formula the Academy of Nutrition and Dietetics regards as the most accurate, then multiply by an activity factor to estimate maintenance calories.

We show calorie targets for losing, maintaining or gaining weight; the activity multipliers we apply are listed in our methodology.

What is TDEE?

Total Daily Energy Expenditure (TDEE) is the total number of calories you burn in a day, including your basal metabolism, physical activity, and the energy used to digest food. Understanding your TDEE is the foundation for any nutrition plan.

Calorie Deficit and Surplus

  • Weight loss: Eat fewer calories than your TDEE. A 500-calorie daily deficit leads to roughly 1 pound of fat loss per week.
  • Weight gain: Eat more calories than your TDEE. A 500-calorie daily surplus supports about 1 pound of weight gain per week.
  • Maintenance: Eat approximately your TDEE to maintain your current weight.

Why 500 Calories ≈ 1 lb/Week

One pound of body fat stores approximately 3,500 calories. A deficit of 500 calories per day over 7 days totals 3,500 calories, resulting in roughly one pound of fat loss. This is an approximation, as metabolism adapts over time.

Macronutrient Balance

A common balanced split for general health is:

  • Protein: 30% of calories (supports muscle maintenance)
  • Carbohydrates: 40% of calories (primary energy source)
  • Fat: 30% of calories (hormones and nutrient absorption)

When to Use This Calculator

  • Starting a diet: Find your maintenance calories before creating a deficit to avoid under-eating.
  • Weight loss plateau: Re-calculate after losing 10+ lbs, since your TDEE changes as your weight changes.
  • Muscle building: Determine the right surplus before a bulking phase, 200-300 calories over TDEE minimizes fat gain.

Real-World Examples

Example 1, Weight loss: 35-year-old male, 5'9", 195 lbs, moderately active. TDEE ≈ 2,700 cal. Loss target: 2,200 cal/day. Expected rate: 1 lb/week. Adjust after 4-6 weeks based on actual results.

Example 2, Maintenance after goal: 28-year-old female, 5'5", 135 lbs, lightly active. TDEE ≈ 1,820 cal. She can eat 1,750-1,900 cal/day and expect stable weight.

Limitations & Assumptions

  • Accuracy is typically ±10% - individual metabolism varies due to genetics, hormones, and gut microbiome.
  • The Mifflin-St Jeor formula is validated for adults 18-65 with average body composition.
  • Activity multipliers are approximations, fitness trackers often overestimate calorie burn by 15-30%.
  • Does not account for adaptive thermogenesis, metabolism slows during prolonged caloric restriction.

Data Sources

BMR formula: Mifflin-St Jeor equation (1990), validated in Frankenfield et al. (2005) as the most accurate for non-obese individuals. Activity multipliers from the Harris-Benedict revision (Roza & Shizgal, 1984). Deficit/surplus relationship per National Institutes of Health (NIH) guidelines.

Related Data

Track calories and nutrition facts for 2M+ foods at USDA FoodData Central. Explore vitamin and supplement data at NIH ODS.

Disclaimer: This calculator provides estimates for informational purposes only. Consult your healthcare provider for medical advice.

After you get your TDEE

What to do with the numbers

  • Start at your maintenance TDEE and apply a 500-calorie deficit or surplus from there, not a round guessed number - the 3,500-calorie-per-pound math above only holds when the starting point is accurate.
  • Re-run the calculator after losing or gaining 10+ pounds, your TDEE shifts with body weight, so an old target under- or over-shoots as you progress.
  • Give the target 4-6 weeks and track actual results before adjusting further - the ±10% accuracy range means the first number is a starting estimate, not a fixed truth.
  • If cutting for a bulking or cutting phase, keep the surplus/deficit modest (200-300 cal) as the examples above show - a large swing mostly adds fat or muscle-loss risk, not speed.

Methodology & Assumptions

This screening tool implements published anthropometric or energy-balance formulas on the measurements you enter. Outputs are arithmetic aids, not clinical judgements—see cited references below.

How this body-metric node runs

Anthropometric and energy estimators implement published screening formulas. They are arithmetic aids, not clinical judgements. Published domain formulas govern the identities; when an agency updates rates or thresholds we refresh defaults and the page lastmod.

Frequently Asked Questions

What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic life-sustaining functions like breathing, circulation, and cell production while at complete rest. It represents the minimum energy your body requires if you were to stay in bed all day. BMR typically accounts for 60-75% of your total daily calorie expenditure.
How accurate are calorie calculators?
Calorie calculators using the Mifflin-St Jeor equation provide a reasonable estimate, typically within 10% of actual needs for most people. However, individual variation in metabolism, genetics, body composition, and other factors means your true calorie needs may differ. Use the calculator as a starting point and adjust based on your real-world results over 2-4 weeks.
Should I eat back exercise calories?
It depends on your goals. If you are trying to lose weight, eating back all exercise calories may slow progress since calorie burn estimates from fitness trackers are often inflated by 15-30%. A common approach is to eat back about half of exercise calories. If you are maintaining or gaining weight, eating back exercise calories helps ensure adequate fueling.
What's the minimum safe calorie intake?
Health professionals generally recommend that women consume at least 1,200 calories per day and men at least 1,500 calories per day, unless under medical supervision. Very low-calorie diets below these thresholds can cause nutrient deficiencies, muscle loss, metabolic slowdown, and other health problems. Always consult a healthcare provider before starting a restrictive diet.

This page identifies the inputs, method, and limitations behind its estimates. CalcMesh does not publish lender, insurer, provider, or plan fee schedules. Any monetary output is calculated from the inputs shown on the page, not a current quote. Compare a fee, rate, or term with the governing agreement or disclosure before a consequential decision. Calculator outputs are not professional advice. Body-metric outputs here apply published formulas to your measurements—no clinical record is assumed. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.

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Inputs, defaults, and authoritative sources
Input Default Source / authority
All inputs Domain-typical defaults Editorial methodology, CalcMesh 2026