How accurate is the Mifflin-St Jeor equation for maintenance calories?

The Mifflin-St Jeor formula, published in 1990, is the most validated BMR formula for general adults and is recommended by the Academy of Nutrition and Dietetics. It estimates BMR within plus or minus 10 percent of measured metabolic rate for most people. The activity multiplier adds more uncertainty since people tend to overestimate their activity level.

How many calories should a woman eat to maintain her weight?

A sedentary 35-year-old woman at 65 kg and 165 cm has a BMR of about 1,427 kcal and a maintenance TDEE of about 1,712 kcal per day. A moderately active woman of the same stats would have a TDEE of about 2,212 kcal per day. The range across all activity levels for average adult women is roughly 1,600 to 2,600 kcal per day.

How many calories should a man eat to maintain his weight?

A sedentary 35-year-old man at 80 kg and 178 cm has a BMR of about 1,838 kcal and a maintenance TDEE of about 2,206 kcal per day. At a moderately active level the same man needs about 2,849 kcal per day. The typical range for adult men across activity levels is roughly 2,000 to 3,500 kcal per day.

Do maintenance calories decrease as you age?

Yes. BMR decreases by roughly 1 to 2 percent per decade after age 30 due to gradual muscle loss and metabolic changes. A 55-year-old has a meaningfully lower BMR than a 25-year-old at the same weight and height. This is one reason body composition tends to shift with age even when eating the same amount. Resistance training helps preserve muscle mass and slow the BMR decline.

What macros should I eat at maintenance calories?

A balanced maintenance split is approximately 25 percent protein (4 kcal per gram), 45 percent carbohydrates (4 kcal per gram), and 30 percent fat (9 kcal per gram). For a person with a TDEE of 2,400 kcal, this means roughly 150 g protein, 270 g carbs, and 80 g fat per day. Protein should be at least 1.4 g per kg of body weight to preserve muscle mass.

What happens if I eat exactly at my maintenance calories every day?

Eating precisely at your TDEE should result in stable body weight over time. In practice, small day-to-day fluctuations in weight (0.5 to 2 kg) are normal due to water retention, glycogen levels, and digestive contents. A true trend of stable weight averaged over two to three weeks is the real indicator that you are eating at maintenance. Daily fluctuations do not indicate fat gain or loss.

Maintenance Calorie Calculator

Q: How do I calculate my maintenance calories?

Maintenance calories equal your Basal Metabolic Rate (BMR) multiplied by an activity factor. BMR is calculated using the Mifflin-St Jeor formula: 10 times weight in kg, plus 6.25 times height in cm, minus 5 times age, plus 5 for men or minus 161 for women. Multiply the result by 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active, or 1.9 for extra active to get your TDEE.

Q: What is the difference between BMR and maintenance calories?

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest to keep organs functioning. Maintenance calories (TDEE) include BMR plus all activity: exercise, walking, standing, and daily movement. TDEE is always higher than BMR. Most adults have a TDEE 20 to 80 percent above their BMR depending on activity level.

Q: What activity level should I choose for the most accurate result?

Sedentary covers desk jobs and minimal movement. Lightly Active covers office work plus 1 to 3 days of exercise per week. Moderately Active fits 3 to 5 days of moderate exercise per week. Very Active applies to hard training 6 to 7 days per week. Extra Active means both a physically demanding job and daily hard training. When uncertain, pick one level below your instinct since activity is commonly overestimated.

Find exactly how many calories your body needs each day to stay at its current weight, with a full macros breakdown and per-meal guide.

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Carbohydrates (at maintenance)

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🔥 What is a Maintenance Calorie Calculator?

Maintenance calories are the total number of calories your body needs each day to keep your current weight perfectly stable. Eating exactly at this level means no fat is gained and no fat is burned: the energy in equals the energy out. Your maintenance calorie level is also called your Total Daily Energy Expenditure (TDEE), and it is the single most important number in any nutrition plan.

This calculator finds your maintenance calories in two steps. First, it calculates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, which estimates the calories your body burns at complete rest to keep your heart beating, lungs breathing, and organs functioning. Then it multiplies your BMR by an activity factor that accounts for everything you do on top of resting: walking, exercising, standing at work, and all other daily movement. The product of BMR and the activity factor is your TDEE, or maintenance calorie level.

Knowing your maintenance calories is the foundation of every nutrition goal. To lose fat, you eat below your TDEE and create a calorie deficit. To gain muscle, you eat above your TDEE and create a calorie surplus. To simply maintain your current weight, you match your intake to your TDEE. Without this number, any diet plan is built on guesswork. A person who needs 2,400 kcal per day and eats 2,000 kcal thinking it is maintenance will slowly lose weight. A person eating 2,800 kcal will slowly gain fat without understanding why.

The Mifflin-St Jeor formula, developed in 1990, is the most widely validated BMR equation for general adults and is the current recommendation of the Academy of Nutrition and Dietetics. It accounts for body weight, height, age, and biological sex. The result is a personalised estimate accurate to within plus or minus 10 percent for most adults, making it the best available formula for population-level calorie planning without a metabolic lab test. This calculator also breaks your maintenance calories into a recommended macronutrient split, per-meal guide, and weekly calorie budget to help you turn the number into a practical eating plan.

📐 Formula

BMR (male) = 10W + 6.25H − 5A + 5

BMR (female) = 10W + 6.25H − 5A − 161

TDEE = BMR × Activity Factor

W = body weight in kilograms

H = height in centimetres

A = age in years

Activity Factor = 1.200 (sedentary), 1.375 (lightly active), 1.550 (moderately active), 1.725 (very active), 1.900 (extra active)

Example: A 30-year-old man, 75 kg, 178 cm, moderately active: BMR = 10(75) + 6.25(178) - 5(30) + 5 = 1,772 kcal. TDEE = 1,772 x 1.55 = 2,747 kcal/day.

The Mifflin-St Jeor equation (1990) is cited in: Mifflin MD et al., "A new predictive equation for resting energy expenditure in healthy individuals," American Journal of Clinical Nutrition, 1990. The activity multipliers are standard Harris-Benedict activity factors as published and validated for use with any BMR formula.

To convert TDEE into macros at maintenance: protein at 25% of calories divided by 4 kcal/g, carbohydrates at 45% divided by 4 kcal/g, and fat at 30% divided by 9 kcal/g. These proportions align with USDA Dietary Guidelines for Americans for a balanced maintenance diet.

📖 How to Use This Calculator

Steps

Choose units and gender - Select Metric or Imperial using the unit tabs at the top of the widget. Select Male or Female using the gender tabs. The Mifflin-St Jeor formula uses a different constant for each sex.

Enter your measurements - Input your body weight, height, and age using the sliders or type directly into the number fields. Default values are pre-filled so a result is visible immediately.

Select your activity level - Choose the option from the dropdown that best matches your typical week. When unsure, go one level lower than your instinct, as most people overestimate their activity.

Read your results - Your maintenance calories (TDEE), BMR, macros in grams, per-meal estimate, and weekly calorie budget all appear in the results panel. Use Copy Link to save your personalised result.

💡 Example Calculations

Example 1 - Moderately Active 30-Year-Old Man

Male, 30 years old, 75 kg, 178 cm, moderately active (gym 4 days/week)

BMR = 10(75) + 6.25(178) - 5(30) + 5 = 750 + 1,112.5 - 150 + 5 = 1,717.5 kcal/day

TDEE = 1,717.5 x 1.550 = 2,662 kcal/day (moderately active factor)

Macros at maintenance: Protein = (2,662 x 0.25) / 4 = 166 g, Carbs = (2,662 x 0.45) / 4 = 299 g, Fat = (2,662 x 0.30) / 9 = 89 g

Maintenance calories = 2,662 kcal/day (18,634 kcal/week)

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Example 2 - Sedentary 45-Year-Old Woman

Female, 45 years old, 62 kg, 163 cm, sedentary (desk job, minimal exercise)

BMR = 10(62) + 6.25(163) - 5(45) - 161 = 620 + 1,018.75 - 225 - 161 = 1,252.75 kcal/day

TDEE = 1,252.75 x 1.200 = 1,503 kcal/day (sedentary factor)

Per meal (3 meals): 1,503 / 3 = 501 kcal per meal. Weekly budget: 1,503 x 7 = 10,521 kcal

Maintenance calories = 1,503 kcal/day

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Example 3 - Very Active 25-Year-Old Man

Male, 25 years old, 85 kg, 183 cm, very active (competitive athlete training daily)

BMR = 10(85) + 6.25(183) - 5(25) + 5 = 850 + 1,143.75 - 125 + 5 = 1,873.75 kcal/day

TDEE = 1,873.75 x 1.725 = 3,232 kcal/day (very active factor)

Macros: Protein = (3,232 x 0.25) / 4 = 202 g, Carbs = (3,232 x 0.45) / 4 = 363 g, Fat = (3,232 x 0.30) / 9 = 108 g

Maintenance calories = 3,232 kcal/day (22,624 kcal/week)

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❓ Frequently Asked Questions

How do I calculate my maintenance calories?+

Maintenance calories equal your BMR multiplied by an activity factor. BMR is calculated using the Mifflin-St Jeor formula: 10 times weight (kg) + 6.25 times height (cm) - 5 times age + 5 (men) or - 161 (women). Multiply by 1.2 (sedentary), 1.375 (lightly active), 1.55 (moderately active), 1.725 (very active), or 1.9 (extra active) to get your TDEE. This calculator performs all these steps instantly.

What is the difference between BMR and maintenance calories (TDEE)?+

BMR is the calories your body burns at complete rest to sustain basic organ function. TDEE (maintenance calories) includes BMR plus all energy burned through physical activity, exercise, and daily movement. TDEE is always higher than BMR. For a sedentary person it is 20 percent higher (factor 1.2). For a very active person it can be 70 to 90 percent higher (factor 1.725 to 1.9).

How accurate is the Mifflin-St Jeor maintenance calorie formula?+

The Mifflin-St Jeor equation estimates BMR within plus or minus 10 percent for most healthy adults. The activity multiplier adds further uncertainty since people frequently overestimate their activity level. Combined, the total TDEE estimate is typically within 10 to 15 percent of true energy expenditure. Track your actual weight for two to three weeks at the calculated intake to calibrate your personal maintenance figure.

How many calories should a woman eat to maintain weight?+

For an average adult woman aged 30 to 40 at a healthy body weight, maintenance calories range from roughly 1,600 kcal per day (sedentary, smaller frame) to 2,600 kcal per day (very active, larger frame). The exact figure depends on weight, height, age, and activity level. Use the calculator above with your specific measurements for a personalised estimate.

How many calories should a man eat to maintain weight?+

For an average adult man aged 30 to 40 at a healthy weight, maintenance calories typically range from 2,000 kcal per day (sedentary, lighter frame) to 3,500 kcal per day (very active, heavier frame). Taller, heavier, and younger men have higher TDEE. Enter your exact stats above for a precise personal estimate.

Does maintenance calorie intake change as you age?+

Yes. BMR declines roughly 1 to 2 percent per decade after age 30 due to gradual lean muscle loss (sarcopenia) and changes in metabolic rate. A 55-year-old has a meaningfully lower TDEE than a 30-year-old with identical weight and height. Resistance training slows this decline by preserving muscle mass. Recalculate your maintenance calories every year or whenever your weight or activity level changes significantly.

What activity level should I choose for the most accurate TDEE?+

Sedentary means a desk job and little movement outside it. Lightly Active covers 1 to 3 formal exercise sessions per week on top of a mostly sedentary lifestyle. Moderately Active covers 3 to 5 sessions per week with a non-physically-demanding job. Very Active means hard training 6 to 7 days per week. Extra Active applies to people with both a physically demanding job and daily hard training. Most gym-goers who train 3 to 4 days fall in the Moderately Active range.

What macros should I eat at my maintenance calories?+

A balanced maintenance split is approximately 25 percent protein (4 kcal/g), 45 percent carbohydrates (4 kcal/g), and 30 percent fat (9 kcal/g). For a 2,400 kcal maintenance level this means roughly 150 g protein, 270 g carbs, and 80 g fat. Higher protein intakes (30 to 35 percent) are recommended if you do regular resistance training to preserve or build muscle.

How often should I recalculate my maintenance calories?+

Recalculate whenever your weight changes by 3 to 5 kg, your activity level changes noticeably, or every 4 to 6 weeks during an active diet phase. Weight loss reduces BMR because less tissue requires maintenance. Using a stale maintenance figure after significant weight change causes an unintentional surplus or deficit that stalls progress.

Is the weekly calorie budget more useful than the daily maintenance figure?+

For many people, yes. The weekly total (TDEE x 7) determines body composition trends more reliably than any single day's intake. If you eat more on training days and less on rest days, matching the weekly budget still achieves maintenance. For a person with a 2,500 kcal TDEE, the weekly budget is 17,500 kcal. Flexible approaches that hit the weekly total are equally effective to rigid daily targets for weight maintenance.

What happens if I consistently eat above my maintenance calories?+

Eating above your TDEE creates a calorie surplus. A surplus of roughly 3,500 to 7,700 kcal accumulates as approximately 0.5 to 1 kg of body weight (mostly fat, with some lean tissue). Eating 250 kcal above maintenance daily adds roughly 0.25 kg per week. Resistance training during a surplus shifts more of the gain toward muscle and less toward fat, but a surplus without training is almost entirely stored as body fat.

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📌 Quick Tips

💡Your maintenance calories change when your weight changes. Recalculate every 4 to 6 weeks or after any 3 to 5 kg shift in body weight to keep your daily target accurate.

💡Activity level is the most common input error. Most gym-goers who train 3 to 4 days per week are Moderately Active, not Very Active. Very Active applies to competitive athletes training hard 6 to 7 days per week.

💡Maintenance calories are a personal baseline, not a fixed number. If your weight drifts up or down after 2 to 3 weeks at your calculated target, adjust by 100 to 200 kcal in the relevant direction.

💡The Mifflin-St Jeor formula estimates BMR within plus or minus 10 percent for most adults. Track your actual weight weekly for two to three weeks and treat the calculator result as a starting estimate, not a law of physics.

💡Your weekly calorie budget is maintenance calories multiplied by seven. Spreading calories unevenly across days is fine as long as the weekly total matches the budget.