Find your daily calorie target, weekly loss rate & projected goal date
0% of journey complete at start
Based on 35% protein, 40% carbs, 25% fat split — adjustable to your preference.
⚠️ These results are estimates for informational purposes only and are not medical advice. Consult a qualified health professional before making significant dietary changes.
First, find your maintenance calories using the Mifflin-St Jeor equation for BMR, multiplied by your activity level. Then subtract your desired deficit. A deficit of 500 calories per day typically results in about 1 pound (0.45 kg) of weight loss per week, since 1 pound of body fat contains approximately 3,500 calories.
A deficit of 10–25% below maintenance is generally considered safe and sustainable for most adults. This translates to roughly 300–750 calories per day for most people. Deficits above 25% should only be attempted under medical supervision, as they can lead to muscle loss, nutrient deficiencies, and metabolic adaptation.
Losing 2 pounds per week requires a daily deficit of about 1,000 calories (2 × 3,500 ÷ 7). This is an aggressive rate that may not be sustainable for everyone. A more moderate target of 1 pound per week (500 calorie daily deficit) is typically recommended for long-term success.
If you use an activity multiplier that already accounts for your exercise (as this calculator does), you should not eat back exercise calories — they are already included in your maintenance calculation. If you use a sedentary multiplier and log exercise separately, then you would add those calories back. Pick one method and be consistent.
Common reasons include underestimating food intake, overestimating activity level, water retention from sodium or hormones, metabolic adaptation over time, and muscle gain offsetting fat loss on the scale. Track your intake carefully for a week, weigh yourself consistently under the same conditions, and consider taking body measurements rather than relying solely on scale weight.
Yes. The Mifflin-St Jeor equation works for all body types. If you have a BMI above 35, you may get more accurate results by using your target weight instead of your current weight in the calculation, as BMR equations can overestimate energy needs at very high body weights.
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Estimates only. Not medical or nutritional advice. Full disclaimer · Terms
A calorie deficit occurs when you consume fewer calories than your body burns in a day. This forces your body to tap into stored energy — primarily body fat — to make up the difference. The result is weight loss. The concept is simple: if you eat less than you burn, you lose weight. But figuring out the right number of calories to eat requires knowing your maintenance level first, which depends on your age, sex, height, weight, and activity level.
The Toolzie Calorie Deficit Calculator uses the Mifflin-St Jeor equation — the most widely recommended BMR formula in clinical nutrition — to estimate your Basal Metabolic Rate. It then multiplies this by an activity factor to find your Total Daily Energy Expenditure (TDEE), which is your maintenance calorie level. From there, you choose a deficit percentage (10–25%) and the calculator shows you exactly how many calories to eat per day, how fast you will lose weight, and when you can expect to reach your goal.
To use the calculator, enter your age, sex, height, and current weight. Select your activity level, choose a deficit intensity, and optionally enter your target weight for a projected timeline. Click Calculate and get your personalized daily calorie target, weekly weight loss rate, macro breakdown, and estimated goal date — no signup, no tracking, completely free.
10% deficit (gentle, ~300–400 cal/day): This is the most sustainable rate for long-term weight loss. You will lose about 0.25–0.4 kg (0.5–0.8 lb) per week. It is ideal if you are close to your goal weight, new to dieting, or want to minimise hunger and muscle loss. The slower rate makes it easier to maintain your social life and training performance.
15% deficit (moderate, ~450–600 cal/day): A balanced choice that produces 0.4–0.6 kg (0.8–1.2 lb) of weight loss per week. This is the most commonly recommended deficit in the research literature because it hits the sweet spot between meaningful progress and sustainability. Most people can maintain a 15% deficit for 8–12 weeks before needing a diet break.
20% deficit (aggressive, ~600–800 cal/day): This produces 0.55–0.8 kg (1.2–1.7 lb) of weekly loss. It is effective for time-limited goals but requires more attention to protein intake, micronutrient density, and recovery. Consider taking a 1-week diet break every 4–6 weeks where you eat at maintenance to reverse metabolic adaptation.
25% deficit (maximum safe, ~750–1000 cal/day): The upper limit of what is generally considered safe without medical supervision. You can expect 0.7–1.0 kg (1.5–2.2 lb) of weekly loss. At this level, protein intake becomes critical to preserve muscle mass, and you should monitor for signs of fatigue, irritability, and training performance decline.
The Mifflin-St Jeor equation, published in 1990, is the BMR formula recommended by the Academy of Nutrition and Dietetics. For men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. This gives you the calories your body burns at complete rest.
Your TDEE (maintenance calories) is BMR multiplied by an activity factor: sedentary (1.2), lightly active (1.375), moderately active (1.55), very active (1.725), or extra active (1.9). The calculator applies your chosen deficit percentage to this maintenance number to produce your daily calorie target.
The weight loss projection uses the widely cited 3,500 calories per pound (7,700 per kg) model. Real-world weight loss is not perfectly linear — water retention, glycogen changes, and metabolic adaptation cause fluctuations — but this model provides a useful estimate for planning purposes. Recalculate every 2–4 weeks as your weight changes, since your maintenance calories decrease as you get lighter.