Calorie Deficit Calculator
Calculate your TDEE, set your ideal calorie deficit, and get a personalized macro plan and weight loss timeline
Age 15–80 years
Optional — used to calculate your weight loss timeline
Enter Your Details to Calculate
Fill in your age, height, weight, and activity level to get your personalized calorie deficit plan.
How to Use the Calorie Deficit Calculator
Enter Your Physical Stats
Select your unit system (imperial or metric), then enter your sex, age, height, and current body weight. These inputs are used to calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor formula by default. Accurate inputs will produce more accurate results — weigh yourself in the morning before eating for the most consistent reading.
Set Your Activity Level
Choose the activity level that best reflects your typical week — not your ideal week. Most office workers with occasional exercise fall into Sedentary or Lightly Active. If you exercise 3–5 times per week, choose Moderately Active. Only select Very Active or Extra Active if you do genuinely hard physical work or training six or more days per week. Overestimating your activity level is one of the most common reasons people don't lose weight despite eating at their target.
Choose Your Deficit Strategy and Goal Weight
Select Mild, Moderate, Aggressive, or Custom as your deficit approach. For most people starting out, Moderate is the best choice — it produces consistent progress without extreme restriction. Enter your goal weight to instantly see your estimated timeline and goal date. The calculator will warn you if your selected deficit pushes your calorie intake below safe minimums.
Review Your Macro Breakdown and Timeline
Your results show your daily calorie target, a full protein/fat/carbs breakdown in grams, a donut chart of your macro split, a side-by-side comparison of all three deficit strategies, and your projected weight loss timeline by month. Use the Advanced Options section to switch BMR formulas or enter your body fat percentage for the more accurate Katch-McArdle calculation.
Frequently Asked Questions
How big should my calorie deficit be?
The ideal deficit size depends on your starting weight, goals, and how sustainable you can make it. A moderate deficit of 20 to 25 percent below your TDEE — typically 400 to 600 calories per day — is the most widely recommended starting point. It produces 0.5 to 1.0 pounds of fat loss per week, which is fast enough to see real progress but slow enough to preserve muscle and avoid the metabolic adaptation that comes with extreme restriction. Larger deficits are not more efficient over time: the body adapts by reducing metabolic rate, increasing hunger hormones, and breaking down muscle tissue for energy. For people very close to their goal weight, a mild deficit of 10 to 15 percent is usually more appropriate to minimize the risk of losing lean mass in the final stage of a cut.
What happens if I eat too few calories — below 1200 or 1500 per day?
Eating below 1,200 calories per day (for women) or 1,500 calories per day (for men) on a sustained basis poses serious health risks. At these very low intake levels, it becomes nearly impossible to meet daily requirements for protein, essential fatty acids, vitamins, and minerals — even with careful food selection. The body responds to severe restriction by aggressively breaking down muscle tissue for energy, reducing its metabolic rate, lowering thyroid hormone output, and elevating hunger hormones like ghrelin. This metabolic slowdown makes future weight loss harder and increases the likelihood of rapid regain when normal eating resumes. Very low calorie diets should only be pursued under medical supervision. This calculator caps recommendations at the safe minimum floor to protect users from inadvertently setting targets that are dangerously low.
Why is my weight loss slower than the calculator predicts?
Several factors cause real-world weight loss to differ from calculated predictions. The 3,500 calorie per pound rule is a simplified model that assumes all lost weight is body fat — in reality, some initial loss is water weight and glycogen, and some may be lean mass. Metabolic adaptation causes the body to gradually reduce its energy expenditure in response to calorie restriction, meaning your actual TDEE decreases as you lose weight and eat less. Calorie counting is also inherently imprecise: nutrition labels have a margin of error of up to 20 percent in the United States, and it is easy to underestimate portion sizes. If your weight loss has stalled for two or more weeks at your current deficit, try reducing your daily target by 100 to 200 calories or adding one extra walk per day to increase your TDEE.
How much protein should I eat on a calorie deficit?
Protein is the most important macronutrient to prioritize during a calorie deficit. The research consensus for muscle preservation while cutting is 0.7 to 1.0 grams of protein per pound of body weight (1.6 to 2.2 grams per kilogram). The calculator defaults to 0.8 grams per pound, which is the middle of the evidence-based range and appropriate for most active people. Those who train with heavy weights or who are already lean (below 15 percent body fat for men, below 22 percent for women) may benefit from the higher end of this range — 1.0 gram per pound. Higher protein intake during a deficit is consistently associated with better fat loss, greater muscle retention, and higher levels of satiety and diet adherence compared to lower protein approaches at the same total calorie level.
What is TDEE and how is it calculated?
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day through all activities combined. It is calculated by multiplying your BMR (Basal Metabolic Rate — calories burned at rest) by an activity multiplier that accounts for your movement and exercise. The standard activity multipliers are: 1.2 for sedentary (desk job, little exercise), 1.375 for lightly active (light exercise 1–3 days per week), 1.55 for moderately active (moderate exercise 3–5 days per week), 1.725 for very active (hard exercise 6–7 days per week), and 1.9 for extra active (physical job or twice-daily training). Your TDEE is your maintenance calorie level: eating at your TDEE keeps your weight stable, eating below it creates a deficit for weight loss, and eating above it creates a surplus for weight gain.
Can I build muscle while eating in a calorie deficit?
Yes, under certain conditions — though the process is much slower than building muscle in a calorie surplus. This phenomenon is called body recomposition and is most pronounced in beginners who are new to resistance training, in people returning to training after a long break (muscle memory effect), in significantly overweight individuals, and in those using performance-enhancing compounds. For experienced, lean athletes, meaningful muscle gain during a deficit is very difficult and largely unsupported by evidence. The key to maximizing muscle retention — and potentially achieving some muscle gain — during a deficit is eating adequate protein (0.8 to 1.0 gram per pound of bodyweight), following a structured progressive resistance training program, keeping the deficit moderate rather than aggressive, prioritizing sleep and recovery, and maintaining a high step count or low-intensity cardio rather than relying on large amounts of exhausting cardiovascular exercise.