Calorie Deficit Calculator

Work out how many calories to eat per day to reach a goal weight, with a target date and a weekly weight chart that accounts for metabolic slowdown.

Your weight
Units
How should we plan it?
Maintenance calories (TDEE)
To reach your goal weight
Eat 0 kcal/day
Weekly weight trajectory
Naive linear estimate With metabolic adaptation

For beginners: how to read this plan
The big numberEat that many calories every day. It is your maintenance calories minus a daily deficit.
Why two lines differAs you lose weight your body burns less, so real progress slows below the straight-line guess.
Safe paceLosing more than 1 percent of body weight per week, or eating below your resting needs, raises the warning.
It is an estimateWater weight, sleep, training and food logging accuracy all move the real result week to week.
This is a planning estimate, not medical advice. Rapid weight loss, eating below your resting needs or a goal in an unhealthy BMI range are reasons to speak with a doctor or dietitian.

This calculator turns a goal weight into one daily calorie target. It solves the plan in two directions: pick a weekly pace and it returns the date you reach your goal, or pick a target date and it returns the daily deficit needed to get there on time.

How to use it

Choose a preset or enter your current and goal weight. Switch between metric and imperial units at any time. Pick a planning mode: By rate shows a weekly weight-loss field, By date shows a target-date field, and only the field for the active mode stays visible. For maintenance calories you can enter your own number or let the tool calculate it on the fly from sex, age, height, weight and activity level.

The formulas

One kilogram of body fat stores roughly 7700 calories. The daily calories to eat equal your maintenance calories minus a daily deficit. By rate, the daily deficit is the weekly loss times 7700, divided by seven. By date, the daily deficit is the total weight to lose times 7700, divided by the number of days until the target date. Maintenance calories are estimated from the Mifflin-St Jeor resting metabolic rate multiplied by an activity factor.

Why two lines on the chart

A straight-line estimate assumes weight loss never slows. In reality, a lighter body burns fewer calories, so a fixed daily intake produces a shrinking deficit and a longer timeline. The green line runs a week-by-week simulation that recalculates maintenance calories at each new weight, which is why it bends away from the naive blue line and can plateau before the goal.

Warnings

The plan flags an unsafe pace above 1 percent of body weight per week, a daily intake below your estimated resting needs, and a goal weight that lands in an underweight or still-overweight BMI range.

What is not included

This is a planning estimate. It does not account for water-weight swings, muscle gain from training, medical conditions, medication, hormonal changes, food-logging error, or individual differences in metabolic adaptation. It is not medical or nutrition advice; rapid loss or very low intake is a reason to consult a doctor or dietitian.