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Calorie Deficit Calculator

Set a safe, sustainable calorie target for weight loss based on your TDEE. Includes minimum calorie floor warnings.

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Important safety notice: Never eat below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision. Extreme restriction is dangerous and counterproductive. If you are struggling with body image or disordered eating, please seek help from a qualified professional.

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Calorie Deficit Calculator

kcal
Deficit goal
Daily target
1,700kcal
Est. weekly loss
0.45 kg
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Never eat below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision. Extreme calorie restriction can be dangerous. Consult a dietitian or doctor before starting any weight loss plan.

What Is a Calorie Deficit?

A calorie deficit occurs when you consume fewer calories than your body burns (your TDEE). This forces your body to use stored energy — primarily body fat — to make up the difference. Over time, a consistent calorie deficit leads to weight loss.

The size of your deficit determines the rate of weight loss: approximately 7,700 calories of deficit equals 1 kilogram of fat loss. A daily deficit of 500 kcal therefore results in roughly 0.45 kg (1 lb) of weight loss per week.

Choosing Your Deficit Level

LevelDaily DeficitWeekly Loss (est.)Best For
Mild−250 kcal~0.23 kgSustainable long-term, minimal hunger
Moderate−500 kcal~0.45 kgStandard recommendation for most adults
Aggressive−750 kcal~0.68 kgShort-term only, requires monitoring
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Minimum Calorie Floors

Health professionals broadly recommend that women should not eat below 1,200 kcal/day and men should not go below 1,500 kcal/day without medical supervision. Below these thresholds, it becomes very difficult to obtain adequate vitamins, minerals, and protein, and the risk of muscle loss, fatigue, gallstones, and metabolic slowdown increases significantly.

If your calculated deficit target falls below these floors, reduce the deficit level or consult a doctor or registered dietitian for a supervised plan.

How to Use This Calculator

Start by calculating your TDEE using our TDEE calculator. Enter that value here, then select a deficit level. The calculator will show your daily calorie target and estimated weekly weight loss.

Monitor your progress over 2–4 weeks. If weight is not changing, your TDEE estimate may need adjustment. Weight fluctuates daily due to water retention, so look at trends over time rather than day-to-day changes.

Limitations

Calorie deficit calculations assume linear weight loss, which rarely happens in practice. Water retention, hormonal fluctuations, metabolic adaptation, and changes in exercise can all affect the rate of loss. As you lose weight, your TDEE decreases and your deficit naturally shrinks unless you adjust your intake. These calculations should not be used to justify extreme restriction or disordered eating patterns.

Frequently Asked Questions

How much of a calorie deficit do I need to lose weight?

A 500 kcal/day deficit typically results in ~0.45 kg per week of weight loss. A 250 kcal deficit is milder and more sustainable. Deficits above 750 kcal/day should be monitored by a professional.

What is the minimum number of calories I should eat?

Women should not eat below 1,200 kcal/day and men not below 1,500 kcal/day without medical supervision. Below these thresholds, nutrient deficiency and muscle loss risks increase.

Why does weight loss slow down over time?

As you lose weight, your BMR and TDEE decrease because a smaller body requires fewer calories. This metabolic adaptation means you may need to recalculate periodically.

Is a 1,000 calorie deficit safe?

Generally not recommended without medical supervision. It can lead to muscle loss, nutrient deficiencies, fatigue, and metabolic adaptation. Most professionals recommend 500–750 kcal deficits.

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