Calorie Deficit Calculator
Put a timeline on weight loss.
Calorie Deficit Calculator
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Calculated instantly
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What This Calculator Does
The Calorie Deficit Calculator determines how long it will take to reach a goal weight based on a daily calorie deficit. It converts the weight loss target into days using the 7,700 kcal per kilogram of body fat conversion.
How It Works
Each kilogram of body fat stores approximately 7,700 kcal. Divide total deficit needed (weight loss x 7,700) by your daily deficit to get estimated days.
Example
To lose 10 kg at a 500 kcal/day deficit: 10 x 7,700 / 500 = 154 days, roughly 5 months.
Formula
Days = Weight loss x 7,700 / DeficitReading the Results
Weight to Lose
The difference between your current weight and goal weight.
Days to Goal
The estimated number of days to reach your goal at the given deficit.
Frequently Asked Questions
How big of a calorie deficit is safe?
A 300-700 kcal/day deficit is sustainable for most adults. Larger deficits may cause muscle loss and metabolic adaptation.
Why does weight loss slow down?
As you lose weight, your BMR and TDEE decrease. Recalculate your deficit periodically to stay on track.
Does this account for muscle gain?
No. This is a fat-loss estimate. Strength training may add muscle simultaneously, which affects the scale but not fat-loss trajectory.