BMR stands for Basal Metabolic Rate. It is the number of calories your body burns at rest to maintain basic functions — breathing, circulation, cell production, and body temperature. BMR accounts for approximately 60–70% of total daily calorie expenditure. Our calculator uses the Mifflin-St Jeor equation, which is widely considered the most accurate BMR formula for the general population.

TDEE stands for Total Daily Energy Expenditure. It is the total number of calories you burn in a day, including your BMR plus the energy used during physical activity, digestion (thermic effect of food), and non-exercise activity thermogenesis (NEAT). TDEE = BMR × Activity Multiplier. This is your maintenance calorie level — eating at TDEE keeps your weight stable.

How many calories should a woman eat per day?

The average sedentary adult woman needs approximately 1,600–2,000 calories per day for weight maintenance. Active women may need 2,000–2,400 calories or more. Pregnant women generally need an additional 300–500 calories per day. Breastfeeding women typically need an additional 400–500 calories. These are estimates — your exact needs depend on age, height, weight, and activity level.

How many calories should a man eat per day?

The average sedentary adult man needs approximately 2,000–2,500 calories per day for weight maintenance. Active men may need 2,500–3,000 calories or more. Men engaged in heavy manual labor or intense athletic training may need 3,500–5,000+ calories per day. Use our calculator to get a personalized estimate based on your specific profile.

Is the Mifflin-St Jeor equation accurate?

The Mifflin-St Jeor equation is considered the most accurate BMR formula for the general population, according to the Academy of Nutrition and Dietetics. Research shows it predicts measured BMR within ±10% for most people. It is more accurate than the older Harris-Benedict equation, especially for modern sedentary lifestyles. Individual results may vary due to genetics, thyroid function, body composition, and other factors.

Why am I not losing weight even in a calorie deficit?

Several factors can stall weight loss despite a calorie deficit: metabolic adaptation (your body lowers its TDEE in response to chronic restriction), water retention masking fat loss, inaccurate calorie tracking (studies show people underestimate intake by 20–40%), reduced NEAT (unconsciously moving less), and stress-elevated cortisol promoting fat retention. Try recalculating your TDEE, tracking food precisely for two weeks, and incorporating diet breaks every 6–8 weeks.

What is a good activity multiplier to use?

Use sedentary (×1.2) if you sit most of the day with no exercise. Use lightly active (×1.375) if you exercise 1–3 days per week. Use moderately active (×1.55) if you exercise 3–5 days per week. Use very active (×1.725) if you have a physically demanding job or exercise 6–7 days per week. Use extremely active (×1.9) if you are an athlete in training, manual laborer, or training twice daily. Most people overestimate their activity level — when in doubt, choose the level below.

How quickly is it safe to lose weight?

The CDC and most nutrition authorities recommend losing no more than 0.5–1 kg (1–2 lbs) per week for sustainable fat loss while preserving muscle mass. Faster loss is possible but risks muscle catabolism, nutritional deficiency, gallstones, and hormonal disruption. A rate of 0.5 kg (1 lb) per week requires a 500-calorie daily deficit and is sustainable long-term for most people.

Should I eat back calories I burn through exercise?

This depends on how you calculated your TDEE. If you used an activity multiplier that already accounts for your exercise, do not eat back workout calories — they are already included. If you used a sedentary multiplier and track exercise separately, eating back 50–75% of estimated burn is a reasonable approach (calorie burn estimates from cardio machines are notoriously inaccurate, often by 25–40%).

What are macronutrients and how do they fit into calorie goals?

Macronutrients are protein (4 calories/gram), carbohydrates (4 calories/gram), and fat (9 calories/gram). A typical maintenance split is 30% protein, 40% carbohydrate, 30% fat. For fat loss with muscle preservation, aim for 0.7–1g protein per pound of body weight (approximately 35–40% of total calories from protein). Total calorie intake matters most for weight change; macronutrient ratios matter most for body composition.

Does meal timing affect calorie needs?

Meal timing has a minimal effect on total daily calorie expenditure. Total calories consumed in 24 hours is the dominant factor for weight change. Intermittent fasting works primarily by reducing the eating window and making it easier to maintain a deficit — not because fasting itself burns more calories. Some research shows the thermic effect of food is slightly higher in the morning, but the difference is nutritionally insignificant for most people.

Free Calorie Calculator — Daily Calorie Needs, BMR & TDEE

Q: How many calories should I eat per day?

Most adults need between 1,600 and 3,000 calories per day depending on gender, age, height, weight, and activity level. Women typically need 1,600–2,400 calories and men 2,000–3,000 calories for maintenance. Use the Mifflin-St Jeor equation to calculate your personal BMR, then multiply by your activity factor to find your TDEE — your true daily calorie need.

Q: What is a calorie deficit?

A calorie deficit occurs when you consume fewer calories than your body burns each day. A deficit of 500 calories per day typically produces about 0.45 kg (1 lb) of fat loss per week. A deficit of 1,000 calories per day can produce up to 0.9 kg (2 lbs) per week. Deficits beyond 1,000 calories per day are not recommended as they risk muscle loss and nutritional deficiencies.

Q: How many calories do I need to lose weight?

To lose weight, consume fewer calories than your TDEE. A 500-calorie daily deficit produces approximately 0.45 kg (1 lb) of fat loss per week. For a 750-calorie deficit, expect about 0.67 kg (1.5 lbs) per week. Never go below 1,200 calories per day (women) or 1,500 calories per day (men) without medical supervision, as this risks nutritional deficiency and metabolic adaptation.

Q: How many calories do I need to gain muscle?

To gain muscle, consume more calories than your TDEE — typically 250–500 calories above maintenance per day (a 'lean bulk'). Combined with progressive resistance training, this produces 0.25–0.5 kg (0.5–1 lb) of muscle per week for natural lifters. Higher surpluses (500–1,000 calories above TDEE) accelerate mass gain but increase fat storage.

Age (years)

Weight (kg)

Weight (lbs)

Height (cm)

Activity Level

Your goal

Speed of loss

Your daily calorie target

—

calories per day

BMR

—

kcal at rest

TDEE

—

kcal/day total

Activity

—

activity factor

Lose Weight

🔥

Your Target

—

kcal/day

Maintenance

⚖️

Stable Weight

—

kcal/day

Gain / Build

💪

Your Target

—

kcal/day

📊 Suggested Macronutrient Split — Balanced

Protein —g (30%)

Carbs —g (40%)

Fat —g (30%)

The Mifflin-St Jeor Formula

For Men

                            BMR = 10 × weight(kg)

                                 + 6.25 × height(cm)

                                 − 5 × age

                                 + 5

e.g. 80kg · 180cm · age 30 → 1,855 kcal/day

For Women

                            BMR = 10 × weight(kg)

                                 + 6.25 × height(cm)

                                 − 5 × age

                                 − 161

e.g. 65kg · 165cm · age 28 → 1,439 kcal/day

Formula published: Mifflin MD et al., AJCN, 1990
Endorsed by: Academy of Nutrition & Dietetics

How We Calculate Your Calorie Needs — The Mifflin-St Jeor Formula

Our calculator uses the Mifflin-St Jeor equation, published in the American Journal of Clinical Nutrition in 1990. It is widely regarded as the most accurate BMR formula for the general population — more accurate than the older Harris-Benedict equation, particularly for modern sedentary lifestyles.

The process works in two steps. First, we calculate your BMR — the calories your body burns at complete rest just to stay alive. Then we multiply your BMR by an activity factor to get your TDEE — the true number of calories you burn in a real day of living.

Step	Calculation	What it means
1. BMR	Mifflin-St Jeor	Calories at rest
2. Activity	BMR × factor	Real-day burn (TDEE)
3. Goal	TDEE ± deficit/surplus	Your calorie target

Why not Harris-Benedict? The original 1919 Harris-Benedict equation was derived from a small, physically active dataset. Mifflin-St Jeor (1990) used a larger, more representative modern sample. Studies show Mifflin-St Jeor predicts measured BMR within ±10% for most non-obese adults.

Reference: Mifflin MD et al., A new predictive equation for resting energy expenditure, AJCN 1990

Full Worked Example

Male · 30 yrs · 80 kg · 180 cm · Moderately Active · Goal: Lose 0.5 kg/wk

Step-by-step calculation

10 × 80 (weight) 800

+ 6.25 × 180 (height) + 1,125

− 5 × 30 (age) − 150

+ 5 (male constant) + 5

= BMR 1,780 kcal

× 1.55 (activity) = TDEE

= TDEE (maintenance) 2,759 kcal

− 500 (moderate deficit) − 500

= Daily target (lose) 2,259 kcal

At 2,259 kcal/day this person creates a weekly deficit of 3,500 kcal — approximately 0.45 kg (1 lb) of fat loss per week.

How Many Calories Do You Need Per Day? Understanding Your Result

The number our calculator gives you is your TDEE — your Total Daily Energy Expenditure adjusted for your goal. It's not a rigid rule; it's a scientifically calibrated starting point. Here's what each output means:

BMR: The calories you'd burn if you stayed completely still all day. This is your metabolic floor — do not eat below this number without medical supervision.
TDEE: Your true daily calorie burn including activity. Eating exactly at TDEE keeps your weight stable.
Deficit target (weight loss): TDEE minus 250–750 calories depending on your chosen speed. The NHS and CDC both recommend losing no more than 0.5–1 kg per week for sustainable results.
Surplus target (muscle gain): TDEE plus 250–500 calories. Combined with progressive resistance training, this supports lean mass gain while minimising fat storage.

What If My Results Seem Wrong?

Calorie calculators are population-average estimates. Individual variation — thyroid function, gut microbiome, sleep quality, genetics — can shift your true TDEE by ±15%. Use the calculator as a starting point, track your results for 2–3 weeks, and adjust by 100–200 calories based on actual progress.

Next step: Check your BMI alongside your calorie target →

Calorie Needs by Activity Level — Why It Matters More Than You Think

Activity level is the biggest variable in your calorie calculation — bigger than age, and bigger than minor differences in height or weight. The difference between a sedentary office worker and an extremely active athlete with the same BMR is nearly 1,200 calories per day.

Level	Multiplier	Who this fits
Sedentary	× 1.2	Desk job, no planned exercise
Lightly Active	× 1.375	1–3 workout days/week
Moderately Active	× 1.55	3–5 workout days/week
Very Active	× 1.725	Hard exercise 6–7 days/week
Extremely Active	× 1.9	Athlete / physical labor job

Most people overestimate their activity level. Research shows gym-goers who exercise 3–4 hours per week but sit for the remaining 20+ waking hours are best classified as "lightly active," not moderately active. NEAT (non-exercise activity thermogenesis — fidgeting, walking to the kitchen, standing) matters more than formal exercise sessions for most people.

Calorie Targets by Goal — What to Aim For

Regardless of your TDEE, these are the scientifically recommended adjustment bands for each goal.

Lose Fat · Fast

Aggressive Deficit (–750 kcal)

≈0.7 kg (1.5 lbs) loss/week. Suitable for people with higher BMI. Risk of muscle loss — ensure adequate protein (0.8–1g/lb bodyweight).

Lose Fat · Sustainable

Moderate Deficit (–500 kcal)

≈0.45 kg (1 lb) loss/week. The CDC gold standard. Sustainable for most adults without significant performance drop.

Lose Fat · Slow

Mild Deficit (–250 kcal)

≈0.23 kg (0.5 lbs)/week. Best for athletes who want to preserve performance while slowly cutting body fat during competition prep.

Stable Weight

Maintenance (TDEE)

Eat at your exact TDEE. Weight remains stable. Use this phase during diet breaks, recomposition, or as a reference baseline.

Build Muscle · Clean

Lean Bulk (+250–300 kcal)

≈0.1–0.2 kg/week muscle gain. Minimal fat storage. Recommended for natural lifters who want to optimise body composition over 6–12 months.

Build Mass · Faster

Standard Bulk (+500 kcal)

≈0.25–0.45 kg/week total mass. Some fat gain expected. Suitable during dedicated off-season muscle-building phases for resistance-trained athletes.

10 Expert Tips to Make Your Calorie Target Actually Work

Knowing your numbers is step one. These evidence-backed strategies turn the number into real results.

Weigh food, don't eyeball it

Studies show people underestimate calorie intake by 20–40% using visual estimation. A kitchen scale reduces error to under 5%. One accurate week beats months of guessing.

Take a 2-week diet break every 8 weeks

Eating at maintenance for 2 weeks after 6–8 weeks of deficit restores leptin levels, reduces cortisol, and prevents adaptive thermogenesis — the metabolic slowdown that stalls fat loss.

Prioritise protein at 0.7–1g per lb bodyweight

High protein intake (2.2–2.7g/kg) during a deficit preserves muscle mass and keeps satiety high. Protein also has the highest thermic effect — your body burns 20–30% of protein calories just digesting it.

Don't eliminate entire food groups

Restrictive elimination diets have dropout rates exceeding 70% after 3 months. Building a slight deficit within a flexible, food-inclusive approach produces better long-term adherence and equivalent fat loss.

Recalculate every 4–5 kg of weight change

Your TDEE drops as you lose weight — both because you're lighter and because metabolic adaptation lowers your BMR. Recalculating and adjusting your calorie target every ~4 kg prevents long plateaus.

Sleep is a fat loss tool

Sleeping under 6 hours per night raises ghrelin (hunger hormone) by up to 28% and decreases leptin (satiety hormone) by 18% — making calorie deficits significantly harder to maintain. 7–9 hours supports metabolic health.

Frequently Asked Questions About Calories

Accurate, evidence-based answers to the most common calorie questions.

How many calories should I eat per day?

Most adults need between 1,600 and 3,000 calories per day. Women typically need 1,600–2,400 calories and men 2,000–3,000 for weight maintenance. The exact number depends on your age, height, weight, and — most importantly — activity level. Use the calculator above to get your personalised number using the Mifflin-St Jeor equation.

What is a calorie deficit, and how big should mine be?

A calorie deficit means eating fewer calories than you burn (your TDEE). A 500 kcal/day deficit produces roughly 0.45 kg (1 lb) of fat loss per week — the rate the CDC recommends as sustainable. Deficits beyond 1,000 kcal/day risk muscle loss, nutritional deficiency, hormonal disruption, and rebound weight gain. Start with a 250–500 kcal deficit and adjust based on 2–3 weeks of real results.

What is BMR and how is it different from TDEE?

BMR (Basal Metabolic Rate) is the calories your body needs at complete rest — breathing, heartbeat, cell repair. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor — it's the actual number of calories you burn in a real day. BMR is typically 60–70% of TDEE. You should never eat below your BMR without medical supervision.

How many calories do I need to lose weight?

Subtract 250–750 calories from your TDEE to create a weight-loss deficit. A 500-calorie daily deficit produces about 0.45 kg (1 lb) per week — the CDC-recommended sustainable rate. Never eat below 1,200 calories per day (women) or 1,500 calories per day (men) as this risks nutritional deficiency and muscle loss, even if it exceeds a 500-calorie deficit.

How many calories do I need to gain muscle?

For a lean bulk, add 250–300 calories above your TDEE and aim for 1.6–2.2g of protein per kg of bodyweight. This produces ~0.1–0.2 kg of muscle per week for natural lifters with a few years of training. A larger surplus (500+ kcal) builds mass faster but increases fat storage. Progressive resistance training — not calories alone — drives muscle protein synthesis.

Why am I not losing weight despite eating in a deficit?

The most common causes: (1) Inaccurate tracking — research shows most people underestimate intake by 20–40%. Weigh food for 2 weeks. (2) Metabolic adaptation — chronic deficits lower TDEE by 10–15%. Take a 2-week maintenance break. (3) Water retention — stress, hormonal cycles, and increased carb intake can mask fat loss by retaining 1–3 kg of water. Scale trends over 4+ weeks are more informative than daily weigh-ins.

What is the thermic effect of food?

The thermic effect of food (TEF) is the energy your body uses to digest, absorb, and metabolise nutrients. Protein has the highest TEF at 20–30%, meaning you burn 20–30 calories digesting every 100 protein calories. Carbohydrates have a TEF of 5–10%; fat is 0–3%. High protein diets effectively reduce net calorie intake beyond what the label shows — another reason protein-rich diets are the most effective for fat loss.

What should my macros be for fat loss?

For fat loss with muscle preservation, a good starting split is 35% protein / 35% carbohydrates / 30% fat. Protein should be your fixed anchor at 0.7–1g per pound of bodyweight. Distribute remaining calories between carbs (performance and satiety) and fats (hormonal health). Total calorie deficit matters more than the specific ratio — but protein intake matters most within that deficit.

Does eating less than 1,200 calories work faster?

Short term, yes — long term, no. Very low calorie diets (VLCDs) below 800 kcal/day trigger aggressive metabolic adaptation, significant muscle loss, nutrient deficiencies, gallstone formation, and hormonal suppression. When the diet ends, these adaptations make weight regain faster and more complete. VLCDs should only be used under close medical supervision for specific clinical cases.

How accurate is this calorie calculator?

The Mifflin-St Jeor equation predicts measured BMR within ±10% for most non-obese adults. The activity multiplier adds additional estimation error of ±5–15%. Combined, your TDEE estimate is likely accurate within ±200–300 calories per day. Use it as a calibrated starting point and verify against 2–3 weeks of real-world weight tracking. Individuals with thyroid conditions, PCOS, or other metabolic conditions may see larger deviations.

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How we keep this accurate: The Mifflin-St Jeor formula used in this calculator was validated in Mifflin MD et al., American Journal of Clinical Nutrition, 1990 and is endorsed by the Academy of Nutrition and Dietetics as the most accurate predictive equation for most adults. Activity multipliers follow CDC physical activity guidelines. Calorie deficit and surplus recommendations follow guidance from the CDC Healthy Weight programme. This page was last reviewed June 2026. This tool is for informational purposes only and is not a substitute for professional dietary or medical advice — please consult a registered dietitian for personalised guidance. About CalcMeter →