Calorie Deficit Calculator

Calculate exactly how many calories to eat to reach your goal weight. Get your personalized daily calorie target, projected timeline, and ideal macros — based on your TDEE and the Mifflin-St Jeor formula. Updated .

Weight loss goal

0.5 lb/week 1 lb/week 1.5 lbs/week 2 lbs/week

Age

Sex

Height

Inches (e.g. 5'8" = 68)

Current Weight (lbs)

Goal Weight (lbs)

Activity Level

Weekly Loss Rate (lbs/week)

Safe range: 0.5–2 lbs/week. Max 1% of body weight.

Daily Target

—

calories/day

Daily Deficit

—

below TDEE

Your TDEE

—

maintenance

Goal Date

—

at this rate

Full Breakdown

Compare weight loss speeds side by side. See your projected goal date at different weekly loss rates and how your calorie target changes with each.

📉 Weight Loss Projection

Rate	Cal/Day	Daily Deficit	Weeks	Goal Date

Which rate is right for you?

Your macro split at your daily calorie target. Protein is set high to preserve muscle during weight loss. Adjust the split to match your diet preference.

Diet style

🥗 Standard 🥩 High Protein 🥦 Low Carb 🥑 Keto

Protein

—g

— cal

Carbs

—g

— cal

Fat

—g

— cal

Macro Breakdown

Calorie Deficit Guide — How to Lose Weight ()

A calorie deficit occurs when you consume fewer calories than your body burns. Since one pound of body fat contains approximately 3,500 calories, a deficit of 500 calories per day creates roughly a 1 lb/week weight loss. This is the foundation of virtually every evidence-based weight loss approach — regardless of whether you follow keto, intermittent fasting, low-carb, or any other diet style.

How We Calculate Your TDEE

This calculator uses the Mifflin-St Jeor equation — the most accurate BMR formula available for most adults, validated in multiple peer-reviewed studies. Your Basal Metabolic Rate (BMR) is multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE). Your daily calorie target is TDEE minus your chosen weekly deficit.

Mifflin-St Jeor formula: For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161.

Safe Calorie Deficit Ranges

Weekly Loss	Daily Deficit	Best For	Risk Level
0.5 lb/week	250 cal/day	Maintenance, long-term, minimal muscle loss	Very low
1 lb/week	500 cal/day	Most people — sustainable, proven results	Low
1.5 lbs/week	750 cal/day	Faster results, manageable hunger	Low–moderate
2 lbs/week	1,000 cal/day	Maximum recommended for most people	Moderate
3+ lbs/week	1,500+ cal/day	Not recommended — muscle loss, metabolic adaptation	High

Why Calories In vs Calories Out Works

Despite the popularity of various diets, every controlled study comparing weight loss approaches finds that total caloric intake is the primary driver of fat loss. Low-carb diets work not because carbs are uniquely fattening, but because reducing carbs often reduces total calories. Intermittent fasting works because time-restricted eating often reduces total calories. The macronutrient split matters for satiety, muscle preservation, and health markers — but the calorie deficit is the mechanism of fat loss.

Protein and Muscle Preservation

When losing weight in a calorie deficit, adequate protein intake is critical to preserve lean muscle mass. Research consistently shows that 0.7–1.0 grams of protein per pound of body weight minimizes muscle loss during caloric restriction. Higher protein also increases satiety (keeping you fuller longer), has a higher thermic effect (burns more calories during digestion), and protects metabolic rate from dropping too quickly.

Calorie Deficit and Exercise

Exercise creates additional calorie burn but should not be "eaten back" fully if weight loss is the goal. A common mistake is dramatically overestimating calories burned during exercise. A 30-minute run burns roughly 300 calories — easily undone by a post-workout snack. The most effective approach is to set your TDEE with your exercise level already factored in (as this calculator does), then eat at your deficit consistently. Exercise preserves muscle mass, improves metabolic health, and provides benefits beyond calorie burn.

How many calories should I eat to lose weight?

The exact number depends on your current weight, height, age, sex, and activity level. The calculator above gives your personalized number. As a general guide: most women lose weight eating 1,200–1,500 calories/day and most men at 1,500–1,800 calories/day, but this varies significantly. Never go below 1,200 calories/day for women or 1,500 calories/day for men without medical supervision — very low calorie diets cause muscle loss, nutrient deficiencies, and metabolic adaptation that makes future weight loss harder.

How big of a calorie deficit do I need to lose 1 pound a week?

You need a deficit of approximately 3,500 calories per week — or 500 calories per day — to lose one pound per week. This is based on the well-established estimate that one pound of fat contains roughly 3,500 calories. In practice, early weight loss is often faster due to water weight loss, and later weight loss may slow as your body adapts. A sustained 500-calorie daily deficit is one of the most evidence-based and sustainable approaches to weight loss.

What is TDEE and why does it matter?

TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day including your basal metabolic rate (BMR), digestion (thermic effect of food), and all physical activity. TDEE is your maintenance calorie level — eating exactly at your TDEE means your weight stays the same. Eating below TDEE creates a deficit and causes weight loss. Eating above TDEE causes weight gain. Calculating your TDEE accurately is the foundation of any successful calorie-based weight loss plan.

Why does weight loss slow down over time?

Several factors cause weight loss to plateau. As you lose weight, your body is lighter, so it burns fewer calories doing the same activities — your TDEE decreases. The body also undergoes metabolic adaptation, reducing BMR beyond what weight loss alone predicts. And compliance with a calorie deficit tends to slip over time. The solution is to recalculate your TDEE at your new weight (usually every 10–15 lbs lost) and adjust your calorie target accordingly. This calculator should be recalculated as your weight changes.

Is it safe to eat at a 1,000 calorie deficit per day?

A 1,000 calorie daily deficit (2 lbs/week loss) is the maximum recommended for most people without medical supervision. This is safe for people who are significantly overweight and have plenty of fat to lose. For lighter individuals, a 1,000-calorie deficit may push daily intake below safe minimums (1,200 calories for women, 1,500 for men). At larger deficits, the body accelerates muscle catabolism and adaptive thermogenesis, making it progressively harder to continue losing weight. High protein intake (0.8–1g per pound of bodyweight) is especially important at larger deficits.

Does it matter which macros I eat in a calorie deficit?

For fat loss specifically, total calories matter more than macro split. However, macros significantly affect how easy the deficit is to maintain. High protein diets reduce hunger, preserve muscle, and increase metabolism slightly through the thermic effect of food. Higher carb diets provide better workout performance. Lower carb diets reduce water retention and may improve blood sugar. The best macro split is one you can sustain consistently — which is why the Macros tab above offers four different splits to match your eating preferences.