Calorie Deficit Calculator - How Much to Eat to Lose Weight

Every kilogram of fat stores the same 7,700 kcal

That number does not care about your diet philosophy, meal timing or supplement stack. To lose 1 kg of body fat you need a cumulative deficit of 7,700 kcal. Spread over a week, that is 1,100 kcal per day. The only variable is pace - and pace determines whether you keep your muscle, your sanity and your metabolism intact.

The problem: most people pick the wrong deficit

A 1,000 kcal daily deficit sounds fast - and it is. But for someone with a TDEE of 1,800 kcal, that leaves just 800 kcal to eat. Below 1,200 kcal (women) or 1,500 kcal (men), the body starts cannibalizing muscle, crashing hormones and tanking metabolic rate. The weight comes back faster than it left.

The solution: match the deficit to your TDEE

This calculator computes your TDEE using the Mifflin-St Jeor equation, then subtracts a deficit based on your chosen pace (0.25-1.0 kg/week). If the resulting calories fall below the safe floor, it warns you before you start. You get a week-by-week projection so you know exactly when you will reach your target.

How to use this calculator - step by step

Current weight - your weight today in kg. The calculator uses it for BMR and to calculate total weight to lose.
Target weight - where you want to end up. Must be lower than current weight.
Height, age, sex - feed the Mifflin-St Jeor formula: 10W + 6.25H - 5A (+5 male / -161 female).
Activity level - multiplies BMR to get TDEE. Be honest - overestimating activity inflates your calorie budget.
Weight loss pace - from 0.25 kg/week (gentle) to 1.0 kg/week (intense). The calculator converts this to a daily kcal deficit.
Read results - daily calorie target, timeline in weeks, week-by-week weight table and safety warnings if applicable.

Choosing the right pace - decision table

The right pace depends on how much you have to lose and your TDEE. Faster is not always better.

Pace	Daily deficit	Weekly deficit	Best for
0.25 kg/wk	275 kcal	1,925 kcal	Already lean, last 2-5 kg
0.50 kg/wk	550 kcal	3,850 kcal	Most people - best compromise
0.75 kg/wk	825 kcal	5,775 kcal	Overweight, active individuals
1.00 kg/wk	1,100 kcal	7,700 kcal	Obese, under medical supervision

How long does it take? Weight loss timeline

All figures below assume a 550 kcal/day deficit (0.5 kg per week).

Goal	Weeks	Months	Total deficit
Lose 3 kg	6	~1.5	23,100 kcal
Lose 5 kg	10	~2.3	38,500 kcal
Lose 10 kg	20	~4.6	77,000 kcal
Lose 15 kg	30	~6.9	115,500 kcal
Lose 20 kg	40	~9.2	154,000 kcal

Practical examples

Example 1: Male, 90 kg to 80 kg, 180 cm, 30 yrs, moderately active, 0.5 kg/wk
TDEE: 2,728 kcal - deficit 550 kcal - eat 2,178 kcal/day. Timeline: 20 weeks (~5 months)

Example 2: Female, 75 kg to 65 kg, 165 cm, 28 yrs, lightly active, 0.5 kg/wk
TDEE: 1,993 kcal - deficit 550 kcal - eat 1,443 kcal/day. Timeline: 20 weeks (~5 months)

Example 3: Male, 110 kg to 85 kg, 185 cm, 40 yrs, sedentary, 1.0 kg/wk
TDEE: 2,560 kcal - deficit 1,100 kcal - eat 1,460 kcal/day. Timeline: 25 weeks (~6 months). Warning: near safe minimum!

Example 4: Female, 58 kg to 55 kg, 160 cm, 24 yrs, moderately active, 0.25 kg/wk
TDEE: 1,978 kcal - deficit 275 kcal - eat 1,703 kcal/day. Timeline: 12 weeks (~3 months)

Example 5: Male, 80 kg to 75 kg, 175 cm, 35 yrs, very active, 0.75 kg/wk
TDEE: 2,987 kcal - deficit 825 kcal - eat 2,162 kcal/day. Timeline: 7 weeks (~1.5 months)

FAQ - Frequently asked questions

How many calories less should I eat to lose 1 kg per week?

1 kg of fat equals about 7,700 kcal. To lose 1 kg per week you need a daily deficit of 1,100 kcal. For someone with a TDEE of 2,000 kcal that means eating just 900 kcal/day - dangerously low. This pace is only safe if your TDEE exceeds 2,500 kcal.

What is the minimum safe calorie intake?

Do not drop below 1,500 kcal/day (men) or 1,200 kcal/day (women) without medical supervision. Below these thresholds you risk muscle loss, metabolic slowdown and vitamin deficiencies. A safe deficit is 15-25% of TDEE.

Why has my weight stalled despite being in a deficit?

Common causes: water retention (after exercise, during stress, in the luteal phase for women), inaccurate calorie counting (not weighing food, skipping oils and sauces), or reduced NEAT (you move less unconsciously). Fat loss continues - the scale is masked by water. Give it 2-3 weeks before adjusting.

What is the difference between deficit and calories burned?

Calories burned = energy used during exercise (e.g. 400 kcal on a treadmill). Calorie deficit = difference between what you eat and your total daily expenditure (TDEE). You can burn 400 kcal running, but if you eat 400 kcal extra afterward, there is no deficit.

Can I eat more on training days?

Yes - this is called calorie cycling. Eat e.g. 2,200 kcal on training days and 1,800 kcal on rest days (average 2,000). What matters is the weekly average, not the daily number. Some people also use refeed days - one day per week at TDEE (no deficit) to maintain metabolic rate.

When should I reduce the deficit?

As you approach your target weight, switch to a gentler pace. For the last 3-5 kg, use 0.25 kg/week. The leaner you get, the harder your body fights to hold onto fat - leptin drops, hunger spikes. A smaller deficit means less rebound risk and better long-term maintenance.

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