Calculate your daily calorie deficit for weight loss. See how much to eat below your TDEE and estimate your fat loss timeline.
A calorie deficit is the basic setup for fat loss: when you consistently eat less energy than you expend, your body must make up the difference from stored energy. This calculator helps you sketch a daily deficit based on your Total Daily Energy Expenditure (TDEE), goal weight, and desired rate of loss.
The classic "3,500 calories = 1 pound of fat" rule is a planning shortcut, not a law of human metabolism. Real weight change is dynamic: as you lose weight, your TDEE usually falls because you are moving a smaller body, and prolonged dieting can also reduce energy expenditure a bit beyond the change in body size.
A moderate deficit of 300–500 calories per day is a common starting point for many people. Larger deficits may be useful in some cases, but they are harder to sustain and may increase the risk of lean mass loss or poor adherence.
Without a deficit target, weight-loss planning turns into guesswork. Eating too little can make the process harder to sustain, while eating too close to maintenance makes progress very slow. This calculator gives you a concrete daily calorie target and an estimated timeline so you can plan, then adjust based on real-world results.
Daily Calorie Target = TDEE − Deficit Common deficit levels: • Mild: 250 kcal/day (≈ 0.5 lb/week) • Moderate: 500 kcal/day (≈ 1.0 lb/week) • Aggressive: 750 kcal/day (≈ 1.5 lb/week) Estimated weeks to goal = (Current weight − Goal weight) × 3,500 / (Deficit × 7) Minimum safe intake: ~1,200 kcal/day (women), ~1,500 kcal/day (men)
Result: 2,246 kcal/day, ~31 weeks to goal
TDEE estimated at 2,746 kcal. A 500-calorie deficit yields a target of 2,246 kcal/day. Weight to lose: 95 − 82 = 13 kg (28.7 lbs). At roughly 1 lb/week, the straight-line estimate is about 29 weeks. Accounting for TDEE decreasing as weight drops, a more realistic estimate is closer to 31 weeks. This is a sustainable pace that preserves muscle mass.
Weight loss requires a consistent energy imbalance: calories in must be lower than calories out. That basic principle is well established, but the body is not a perfect calculator. Activity, appetite, sleep, stress, and changes in body size all influence how quickly weight changes in practice.
Larger deficits can speed up scale loss, but they also tend to be harder to maintain. A moderate deficit is usually the most practical starting point when the goal is to lose fat without making the plan miserable.
If your weekly average weight has stalled for 2–3 weeks and tracking is accurate, your actual maintenance may now be lower than the worksheet estimate. In that case, trimming intake a little or increasing activity a little is usually a better move than making a large change all at once.
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This worksheet estimates a daily target as TDEE minus a chosen calorie deficit, then uses a simple calorie-to-weight heuristic to sketch a goal timeline. The timeline is intentionally approximate because real weight loss slows as body weight falls and because individual energy expenditure can drift during dieting.
The calculator is best used as a planning tool. It gives a reasonable starting target, then expects you to compare the worksheet projection with your actual weekly weight trend and adjust gradually.
Yes, for most healthy adults. A 500 kcal/day deficit produces approximately 1 lb of weight loss per week and is widely recommended by health organizations. It preserves muscle mass better than larger deficits, is psychologically sustainable, and doesn't trigger severe metabolic adaptation in most people.
For most people, yes. A 1,000 kcal/day deficit often results in calorie intake below recommended minimums, increases risk of muscle loss and nutrient deficiencies, and can trigger significant metabolic adaptation. It may be appropriate for individuals with obesity under medical supervision, but is not suitable as a general approach.
Two main reasons: (1) As you lose weight, your TDEE decreases because it takes less energy to sustain a smaller body. The same deficit that produced a 500 kcal gap initially may only produce a 350 kcal gap after 20 lbs of loss. (2) Adaptive thermogenesis further reduces your metabolic rate below what equations predict, especially with prolonged dieting.
You don't have to. Calorie cycling (varying daily intake while keeping the weekly average at your target) is an equally valid approach. Some people eat more on training days and less on rest days. What matters is that the average weekly deficit is on target, not that every single day is identical.
Some muscle loss during weight loss is normal, but it can be minimized by: (1) keeping the deficit moderate (no more than 500–750 kcal/day), (2) eating adequate protein (0.7–1.0 g/lb), (3) performing resistance training 2–4x per week, and (4) sleeping 7–9 hours. With these practices, the majority of weight lost will be fat.
Track your morning weight daily (after using the bathroom, before eating) and calculate a weekly average. If the weekly average is trending downward by 0.5–1.5 lbs/week, your deficit is working. Give it at least 2–3 weeks before making adjustments, as water weight fluctuations can mask fat loss.
Metabolic adaptation (adaptive thermogenesis) is your body's response to prolonged calorie restriction. Your metabolism slows beyond what is predicted by weight loss alone — non-exercise activity decreases, thermic effect of food drops, and hormones like leptin and thyroid hormones adjust downward. This is why periodic diet breaks or refeed days can be beneficial.
In theory, yes — a deficit is a deficit whether from eating less or moving more. In practice, creating a large deficit through exercise alone is impractical: burning 500 extra calories requires roughly 45–60 minutes of vigorous exercise daily. A combined approach (moderate calorie reduction + moderate exercise increase) is most sustainable and effective.