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Calorie Deficit Calculator

Find your daily calorie target to reach your goal weight

yrs
ft
in
lbs
lbs
weeks
✅

Healthy pace

499 cal/day deficit · losing ~1.0 lbs/week

Daily Calorie Target

1552

calories / day

Daily Deficit

499

cal below maintenance

Maintenance

2051

cal/day (TDEE)

To Lose

20.0

lbs total

Per Week

1.0

lbs

Based on Mifflin-St Jeor equation. Individual results vary. Consult a healthcare provider before starting any calorie-restricted diet.

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What Is a Calorie Deficit?

A calorie deficit is the gap between how many calories your body uses and how many you consume. Your body burns calories continuously — through breathing, circulation, digestion, and physical movement. The total is called your Total Daily Energy Expenditure (TDEE). When you eat fewer calories than your TDEE, your body has to find the shortfall somewhere. It draws on stored energy reserves, and the primary reserve available in most adults is body fat.

Each kilogram of stored fat contains approximately 7,700 kilocalories of stored energy — about 3,500 calories per pound. A consistent daily deficit of 500 calories produces a weekly deficit of 3,500 calories, which translates to roughly 0.45 kg (1 lb) of fat loss per week. This is the calculation at the heart of every evidence-based weight loss plan, and it is precisely what this calculator performs — taking your stats and timeline and converting them into a concrete daily calorie number.

How the Calculator Works: BMR, TDEE and the Deficit

The calculator runs three sequential calculations. First, it computes your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest — using the Mifflin-St Jeor equation, which is the most accurate formula validated for the general population. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. For men, the formula is identical but adds 5 instead of subtracting 161.

Second, your BMR is multiplied by an activity factor to produce your TDEE — the calories you actually burn in a typical day including all movement. Sedentary (×1.2) covers desk-job lifestyles with minimal exercise. Lightly active (×1.375) fits 1–3 light workout days per week. Moderately active (×1.55) suits 3–5 days of real exercise. Very active (×1.725) applies to daily hard training, and extra active (×1.9) covers athletes with physically demanding jobs.

Third, the required daily deficit is derived from your weight loss goal and timeline. If you want to lose 9 kg in 20 weeks, the total calorie deficit needed is 9 × 7,700 = 69,300 calories. Spread across 20 × 7 = 140 days, that requires a daily deficit of 495 calories. Subtract that from your TDEE to get your daily calorie target.

Worked example: Woman, 30 years old, 5'5", 170 lbs, goal 150 lbs, 20 weeks, lightly active → BMR 1,492 → TDEE 2,052 → required deficit 499 cal/day → daily calorie target 1,553 cal/day. At that intake, she loses approximately 1 lb per week — a healthy, sustainable pace.

How Many Calories Are in a Pound of Fat?

The figure used in most weight loss calculations is 3,500 calories per pound of body fat (7,700 calories per kilogram). This number comes from the measured energy content of human adipose (fat) tissue and has been the basis of fat-loss math since it was first published in the 1950s.

In practice, the relationship is not perfectly linear. As you lose weight, you lose some muscle mass alongside fat — especially at aggressive deficits without adequate protein and resistance training. Muscle contains less stored energy than fat, so the real calorie cost of losing a pound of total body weight varies. Early in a diet, water loss can also produce rapid scale changes that are not fat loss at all.

The 3,500-calorie rule is best understood as an approximation that works well for planning over weeks and months, rather than a precise prediction of any individual day. Use it to set your target and assess progress over 3–4 week windows rather than expecting the scale to move exactly as predicted each day.

Safe vs Aggressive Deficits: Finding the Right Rate

Most health authorities recommend a maximum weight loss rate of 0.5–1 kg (1–2 lbs) per week for most adults, corresponding to a daily deficit of roughly 500–1,000 calories. Within this range:

  • 250 cal/day deficit (0.5 lb/week): Very conservative. Suitable for people who are close to their goal weight or who have a low TDEE and cannot cut more without hitting the safe-intake floor. Progress is slow but very sustainable.
  • 500 cal/day deficit (1 lb/week): The sweet spot for most people. Fast enough to see clear weekly progress, moderate enough to preserve muscle and avoid persistent hunger. This is the rate most nutrition guidelines recommend as a starting point.
  • 750–1,000 cal/day deficit (1.5–2 lbs/week): Aggressive. Achievable for people with high TDEE (above 2,500 calories/day) but increasingly difficult to sustain and more likely to produce muscle loss, fatigue, and rebound eating.
  • Over 1,000 cal/day deficit (more than 2 lbs/week): Not recommended without medical supervision. At this rate, calorie intake often falls below the safe minimum, nutrient deficiencies become likely, and metabolic adaptation accelerates.

This calculator flags when your required deficit exceeds 1,000 calories per day or when the resulting intake falls below 1,200 cal/day (women) or 1,500 cal/day (men), and suggests a safer extended timeline instead.

Diet vs Exercise: How to Split the Deficit

A deficit of 500 calories per day can come from eating 500 fewer calories, burning 500 more through exercise, or any combination — 300 from diet and 200 from exercise, for example. In practice, most successful weight loss programs lean heavily on diet for the majority of the deficit, with exercise playing a supporting role.

The reason is simple arithmetic. Creating a 500-calorie deficit purely through exercise requires about 45–60 minutes of vigorous activity per day — a significant time and energy commitment. Creating the same deficit by eating 500 fewer calories (roughly one large snack or a smaller dinner portion) is far easier to sustain daily. Research consistently shows that dietary restriction produces more weight loss per unit of effort than exercise alone.

That said, exercise plays a critical role in maintaining weight loss, preserving muscle mass during the deficit (especially resistance training), and improving the body composition of the weight you do lose. The most effective approach: create 70–80% of the deficit through diet, use exercise for the remaining 20–30%, and continue exercising after reaching your goal to maintain the new weight. Use the Calorie Burned Calculator to quantify what specific exercises contribute.

Why Your Calorie Target Changes as You Lose Weight

Your TDEE is not fixed — it decreases as you lose weight. A person weighing 180 lbs burns more calories doing the same activities than they do at 160 lbs, because they are moving a heavier body. As you lose weight, your maintenance calories drop, which means the deficit you calculated at your starting weight gradually shrinks even if your diet doesn't change.

This is one reason weight loss often slows as you get closer to your goal — not only is there less fat available, but your body now requires fewer calories to maintain itself. Metabolic adaptation can also play a role: extended caloric restriction can cause the body to slightly reduce its resting metabolic rate as an energy conservation response, though this effect is smaller than the purely mechanical effect of weighing less.

The practical implication: recalculate your TDEE and calorie target every time you lose 5–10% of your body weight, or approximately every 10–15 lbs. Use this calculator to update your numbers and keep the deficit at the rate you originally planned.

Common Mistakes That Stall Weight Loss

Underestimating calorie intake. Studies show people underestimate their food intake by 20–50% on average. Estimating portion sizes visually — especially for oils, sauces, nuts, and cheese — is notoriously inaccurate. Using a kitchen scale for at least the first 2–4 weeks builds an accurate mental model of what portions actually look like and how many calories they contain.

Not tracking liquid calories. Coffee drinks, juice, smoothies, alcohol, and even sparkling water with flavourings can contribute several hundred calories per day that don't register as “eating.” Accounting for beverages often reveals a hidden calorie source responsible for stalled progress.

Expecting linear daily progress. Body weight fluctuates by 1–3 lbs daily due to water retention, hormonal changes, sodium intake, and digestive contents. Weighing yourself once a week at the same time (morning, post-bathroom, before eating) and comparing weekly averages gives a much clearer picture of actual fat loss than daily weigh-ins.

Not adjusting the target over time. As noted above, your TDEE drops as you lose weight. A deficit that produced 1 lb/week at 200 lbs may produce 0.5 lb/week at 170 lbs. Recalculate periodically.

Insufficient protein. Protein has the highest satiety per calorie of any macronutrient, and it is essential for preserving muscle during a calorie deficit. Target 1.6–2.2g of protein per kg of body weight (0.7–1g per lb) while cutting. The Macro Calculator can help set specific protein targets alongside your calorie goal.

What to Do After Reaching Your Goal Weight

Reaching your goal weight is the beginning of maintenance, not the end of tracking. The most common failure mode in weight loss is returning to old eating habits immediately after reaching the target, which causes rapid rebound weight gain.

Maintenance requires eating at your new TDEE — which is lower than it was at your starting weight. Gradually increasing your calorie intake by 100–200 calories per week over 3–4 weeks (often called “reverse dieting”) while monitoring the scale allows you to find your true new maintenance level without overshooting. Most people's real maintenance calories at goal weight differ slightly from the formula prediction.

The longer you maintain at your goal weight, the more stable it becomes — the body adapts to the new weight as its set point over time, and the urge to return to old habits diminishes. Studies show that people who maintain consistent weigh-ins, keep exercise habits established during the diet, and continue tracking food (even loosely) have significantly better long-term weight maintenance outcomes than those who stop all monitoring on reaching their goal.

Frequently Asked Questions

What is a calorie deficit and how does it cause weight loss?+
A calorie deficit occurs when you consume fewer calories than your Total Daily Energy Expenditure (TDEE) — the total number of calories your body burns through metabolism, digestion, and physical activity. When your intake falls below your TDEE, your body draws on stored energy reserves, primarily body fat, to make up the difference. Each kilogram of stored fat holds approximately 7,700 kilocalories (3,500 calories per pound). A consistent daily deficit of 500 calories therefore produces roughly 0.45 kg (1 lb) of fat loss per week. The deficit can come entirely from eating less, entirely from moving more, or — most effectively for most people — a combination of both.
How big of a calorie deficit do I need to lose 1 pound per week?+
A daily calorie deficit of approximately 500 calories produces around 1 pound (0.45 kg) of fat loss per week, because 500 × 7 days = 3,500 calories — roughly equal to the energy stored in one pound of fat. This is the most widely recommended pace: significant enough to see consistent progress on the scale, but moderate enough to preserve muscle tissue, sustain energy and mood, and avoid the metabolic slowdown that accompanies very aggressive restriction. A 250-calorie deficit produces about half a pound per week, which suits people who are already close to their goal weight. Deficits above 1,000 calories per day (more than 2 pounds per week) are not recommended for most people without medical supervision.
Is a 500-calorie daily deficit safe?+
For most healthy adults, a 500-calorie daily deficit is safe and is the rate most health organisations recommend for sustainable fat loss. The key safety check is that the resulting daily calorie intake stays above the minimum: 1,200 calories per day for women and 1,500 calories per day for men. If your TDEE is 2,000 calories, a 500-calorie deficit leaves you at 1,500 calories — comfortably above the floor. If your TDEE is only 1,600 calories, the same deficit puts you at 1,100 calories, below the safe minimum. This calculator enforces the floor and warns when your chosen timeline requires intake below it.
Can I lose weight with exercise alone, without tracking calories?+
Exercise contributes to a calorie deficit, but research consistently shows that diet has a much larger impact on weight loss than physical activity alone. A typical gym session burns 250–400 calories — equivalent to a single modest meal. Without managing food intake, many people unconsciously eat more after exercising, partially or fully cancelling the deficit. A commonly cited estimate is that weight loss is roughly 80% determined by diet and 20% by exercise. Exercise is essential for health, preserving muscle during weight loss, and long-term weight maintenance, but using it as the sole mechanism for creating a meaningful deficit is difficult without also monitoring what you eat.
What is the minimum safe calorie intake for weight loss?+
The general minimum safe calorie intake for weight loss is 1,200 calories per day for women and 1,500 calories per day for men. Eating below these levels makes it very difficult to consume adequate protein, fibre, vitamins, and minerals while eating less food, and increases the risk of muscle loss, nutrient deficiency, fatigue, and hair loss. Very low calorie diets (below 800 calories per day) should only be used under medical supervision. If the calculator shows your target falling below the minimum, it means your chosen timeline is too aggressive — extend the timeframe until the daily intake clears the floor.
Why am I not losing weight despite being in a calorie deficit?+
The most common reason is calorie counting error — research shows people underestimate their food intake by 20–50%, often without realising it. Weighing food on a kitchen scale instead of estimating by volume typically closes this gap significantly. Second, water retention — particularly around menstruation, after high-sodium meals, or when starting a new exercise routine — can mask real fat loss on the scale for 2–4 weeks. Third, as you lose weight your TDEE decreases because you are carrying less mass, so a deficit that produced results at 180 lbs may be insufficient at 160 lbs. Recalculate your TDEE every 10–15 pounds of weight lost and adjust your calorie target accordingly. Finally, stress, poor sleep, and certain medications can slow fat loss independent of calorie intake.
How do I find my TDEE without a calculator?+
The most accurate personal TDEE estimate comes from tracking your actual food intake for 7–14 days without changing your eating habits. If your weight stays stable during that period, your average daily calorie intake equals your TDEE. If you gained slightly, your TDEE is a bit below your average; if you lost slightly, it is a bit above. This empirical method accounts for individual metabolic variation that formula-based estimates cannot capture. As a formula alternative, use the Mifflin-St Jeor equation (as used in this calculator) as a starting point, then monitor your weight weekly for 3–4 weeks and adjust your intake by 100–200 calories if actual weight change does not match the predicted rate.