Calorie Deficit Calculator

What is a calorie deficit calculator?

A calorie deficit calculator turns your maintenance calories and a target rate of weight loss into a daily calorie goal and the deficit you need to reach it. You give it two numbers — your maintenance calories (TDEE) and how much weight you want to lose each week — and it returns the daily deficit, the weekly deficit, and the daily calorie target you should eat at. The tool above does this instantly in your browser.

A calorie deficit simply means eating fewer calories than your body burns, which forces it to draw on stored energy — mostly body fat — to make up the difference. Lose weight too fast and you risk muscle loss, fatigue and hunger; too slow and progress stalls. This calculator helps you pick a rate you can actually sustain and translates it into a single, clear number to eat to each day.

How does the calorie deficit calculator work?

The calculator is built on one well-established conversion: roughly 7,700 kcal per kilogram of body fat, or about 3,500 kcal per pound. To lose a given amount of fat in a week, you simply spread that energy gap across the seven days.

The formula:

• weekly deficit = weekly loss × kcal per unit
• daily deficit = (weekly loss × kcal per unit) ÷ 7
• daily target = TDEE − daily deficit

The terms and units:

• TDEE (maintenance) — your total daily energy expenditure in kilocalories (kcal), the intake that keeps weight stable.
• weekly loss — how much body weight you aim to lose per week, in kilograms or pounds.
• kcal per unit — about 7,700 kcal per kg, or about 3,500 kcal per pound of fat.
• daily deficit — how far below maintenance you eat each day.
• daily target — the calories to actually eat: maintenance minus the daily deficit.

Because the kg and pound conversions describe the same fat, the unit you pick barely changes the result: a loss of 0.5 kg per week and a loss of about 1.1 lb per week produce almost the same deficit.

Examples

Each worked example below matches the tool’s logic exactly: find the weekly deficit, divide by 7 for the daily deficit, then subtract from TDEE.

Example 1 — TDEE 2,500, lose 0.5 kg per week

• Weekly deficit = 0.5 × 7,700 = 3,850 kcal
• Daily deficit = 3,850 ÷ 7 = 550 kcal
• Daily target = 2,500 − 550 = 1,950 kcal per day

Example 2 — TDEE 2,500, lose 1 lb per week

• Weekly deficit = 1 × 3,500 = 3,500 kcal
• Daily deficit = 3,500 ÷ 7 = 500 kcal
• Daily target = 2,500 − 500 = 2,000 kcal per day

This is the classic “1 lb per week is a 500 kcal per day deficit” rule of thumb.

Example 3 — TDEE 2,000, lose 0.25 kg per week

• Weekly deficit = 0.25 × 7,700 = 1,925 kcal
• Daily deficit = 1,925 ÷ 7 = 275 kcal
• Daily target = 2,000 − 275 = 1,725 kcal per day

Example 4 — TDEE 3,000, lose 1 kg per week

• Weekly deficit = 1 × 7,700 = 7,700 kcal
• Daily deficit = 7,700 ÷ 7 = 1,100 kcal
• Daily target = 3,000 − 1,100 = 1,900 kcal per day

Notice how a faster goal demands a much steeper daily cut: a 1 kg per week pace asks for double the deficit of 0.5 kg per week, which is why aggressive targets are harder to sustain.

Calorie deficit reference table

The table shows the daily deficit and the resulting daily target for a person with a maintenance of 2,500 kcal, straight from the formula. Use it as a quick sanity check, then enter your own numbers above.

Weekly goal	kcal per unit	Weekly deficit	Daily deficit	Daily target (TDEE 2,500)
0.25 kg/week	7,700	1,925	275	2,225
0.5 kg/week	7,700	3,850	550	1,950
1 kg/week	7,700	7,700	1,100	1,400
1 lb/week	3,500	3,500	500	2,000
2 lb/week	3,500	7,000	1,000	1,500

Each extra increment of weekly loss adds a proportional chunk to the daily deficit, so the faster you push, the lower — and harder to maintain — your daily target becomes.

Common uses

A deficit figure is the practical bridge between knowing your maintenance and actually losing weight:

• Set a daily calorie goal. Turn a vague “eat less” into a precise number to track against.
• Pick a sustainable pace. Compare 0.25, 0.5 and 1 kg per week to see which target you can realistically stick to.
• Plan a cut. Lifters use it to estimate how long a fat-loss phase will take at a chosen rate.
• Sanity-check a crash diet. See whether an aggressive goal leaves you eating far too little.
• Pair with macros. Once you have a daily target, split it into protein, carbohydrate and fat.

Tips and common mistakes

• Know your TDEE first. The whole calculation hinges on an accurate maintenance figure — estimate it before you set a deficit.
• Do not over-cut. A daily target far below your TDEE can leave you under-fuelled; many guidelines suggest not dropping below about 1,200 kcal (women) or 1,500 kcal (men) without supervision.
• Treat 7,700 kcal per kg as an estimate. It is a useful average, but real loss includes water and a little muscle, so the scale rarely moves in a perfectly straight line.
• Be honest about your weekly goal. A 0.5 to 1 percent of body weight per week pace is sustainable for most people; faster usually means more muscle loss and hunger.
• Re-run as you lose. Your TDEE falls as you get lighter, so recalculate every few weeks to keep the deficit accurate.
• Track real results. If the scale is not moving after two to three weeks, adjust intake by 100 to 200 kcal rather than trusting the math alone.

Limitations and notes

This calculator uses a fixed 7,700 kcal per kg (3,500 kcal per pound) energy density of fat, which is a long-standing average rather than an exact constant for every person. Real weight change also reflects water, glycogen and a portion of lean mass, not pure fat, so day-to-day scale readings can mislead. The model assumes your maintenance stays constant, but TDEE drops as you lose weight and can adapt downward during prolonged dieting, meaning a deficit that worked at the start may slow over time. It does not account for individual metabolism, medical conditions, medications or activity changes.

Health disclaimer: This calorie deficit calculator is provided for general information and education only. It is not medical, nutritional or fitness advice, and it is not a substitute for professional assessment. Before changing your diet or calorie intake, consult a qualified healthcare professional.

To build a full plan, find your maintenance with the TDEE calculator, then split your daily target into protein, carbs and fat with the macro calculator, and browse the full fitness category for more tools.