Calorie Deficit Calculator
Use this calorie deficit calculator to find how many calories to eat each day for your weekly weight-loss goal.
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Alyssa Northrop, MPH, RD
Alyssa Northrop, MPH, RD, is a registered dietitian who earned her MPH in Human Nutrition at the University of Michigan and completed her dietetic internship there.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How a Calorie Deficit Is Calculated
Weight loss comes down to energy balance: eat fewer calories than you burn, and your body draws on stored energy, including body fat, to make up the difference. This calculator converts a weekly weight-loss goal you choose directly into a daily calorie number, rather than leaving you to guess at the math yourself.
What This Calculator Measures
This calorie deficit calculator gives you a single daily calorie target based on your specific weekly loss goal. If you just want your maintenance number with no deficit applied, use the TDEE Calculator instead.
Step 1: Maintenance Calories (TDEE)
We estimate your Basal Metabolic Rate (BMR) with the Mifflin-St Jeor formula¹, then multiply by your activity level to get your maintenance calories, the amount that keeps your weight stable.
Step 2: Size the Deficit to Your Goal
One kilogram of body weight holds roughly 7,700 calories, a figure that traces back to a 1958 analysis of the caloric equivalents of weight gained or lost²."
Daily deficit = (weekly loss goal in kg × 7,700) ÷ 7
Your target calories are your maintenance calories minus this deficit, never dropping below a safe minimum (1,500 kcal for men, 1,200 kcal for women).
How This Calculator Computes Your Result
Enter your sex, age, height, weight, activity level, and weekly loss goal above. We calculate your maintenance calories, apply the deficit formula, and cap the result at the safe minimum if needed.
Why the 7,700 Figure Is a Starting Point, Not a Law
The 1958 estimate assumed that all lost weight comes from pure fat tissue, an assumption that holds up reasonably well for short-term, moderate deficits but breaks down over longer periods².
A more recent mathematical model of body weight regulation, developed by a researcher at the U.S. National Institutes of Health, the same institute behind the NIH Body Weight Planner tool⁴, found that the actual deficit needed per unit of weight lost shrinks as a person gets leaner, since a larger share of continued loss comes from lean tissue rather than fat once fat stores are reduced³.
In practical terms, this means a fixed 7,700-calorie rule tends to overpredict weight loss the longer a diet continues.
A Note on Accuracy
The 7,700-calorie-per-kg figure is a useful planning estimate, not a fixed physical constant. It was derived from 1950s data on the caloric value of lost body weight, and later modeling has shown the real number shifts with your starting body composition and how long the deficit continues. A moderate target is usually easier to sustain. Monitor energy, hunger, performance, and weight trend, then make small adjustments instead of dramatic changes.
Frequently Asked Questions
How large should my calorie deficit be?
A moderate deficit of about 15 to 25% below maintenance is generally more sustainable than an aggressive cut, and tends to preserve more muscle mass along the way.
How fast should I expect to lose weight?
A common, sustainable target is roughly 0.5 to 1% of body weight per week. Faster loss is possible but increases the risk of muscle loss and rebound weight regain.
Why did my weight loss stall on the same calories?
As you lose weight, your maintenance calories drop too, since a smaller body burns less energy, and the deficit needed per unit of further loss also shifts as your body composition changes³. Recalculate periodically to keep your deficit accurate.
Is a bigger deficit always better for results?
Not necessarily. Very large deficits often lead to more muscle loss, fatigue, and difficulty sticking to the plan long term.
Sources
A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals, Mifflin et al., 1990
Caloric Equivalents of Gained or Lost Weight, Wishnofsky, 1958
What Is the Required Energy Deficit per Unit Weight Loss?, Hall, 2008
Body Weight Planner, NIH / NIDDK
Calorie Deficit Calculator
Use this calorie deficit calculator to find how many calories to eat each day for your weekly weight-loss goal.
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Alyssa Northrop, MPH, RD
Alyssa Northrop, MPH, RD, is a registered dietitian who earned her MPH in Human Nutrition at the University of Michigan and completed her dietetic internship there.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How a Calorie Deficit Is Calculated
Weight loss comes down to energy balance: eat fewer calories than you burn, and your body draws on stored energy, including body fat, to make up the difference. This calculator converts a weekly weight-loss goal you choose directly into a daily calorie number, rather than leaving you to guess at the math yourself.
What This Calculator Measures
This calorie deficit calculator gives you a single daily calorie target based on your specific weekly loss goal. If you just want your maintenance number with no deficit applied, use the TDEE Calculator instead.
Step 1: Maintenance Calories (TDEE)
We estimate your Basal Metabolic Rate (BMR) with the Mifflin-St Jeor formula¹, then multiply by your activity level to get your maintenance calories, the amount that keeps your weight stable.
Step 2: Size the Deficit to Your Goal
One kilogram of body weight holds roughly 7,700 calories, a figure that traces back to a 1958 analysis of the caloric equivalents of weight gained or lost²."
Daily deficit = (weekly loss goal in kg × 7,700) ÷ 7
Your target calories are your maintenance calories minus this deficit, never dropping below a safe minimum (1,500 kcal for men, 1,200 kcal for women).
How This Calculator Computes Your Result
Enter your sex, age, height, weight, activity level, and weekly loss goal above. We calculate your maintenance calories, apply the deficit formula, and cap the result at the safe minimum if needed.
Why the 7,700 Figure Is a Starting Point, Not a Law
The 1958 estimate assumed that all lost weight comes from pure fat tissue, an assumption that holds up reasonably well for short-term, moderate deficits but breaks down over longer periods².
A more recent mathematical model of body weight regulation, developed by a researcher at the U.S. National Institutes of Health, the same institute behind the NIH Body Weight Planner tool⁴, found that the actual deficit needed per unit of weight lost shrinks as a person gets leaner, since a larger share of continued loss comes from lean tissue rather than fat once fat stores are reduced³.
In practical terms, this means a fixed 7,700-calorie rule tends to overpredict weight loss the longer a diet continues.
A Note on Accuracy
The 7,700-calorie-per-kg figure is a useful planning estimate, not a fixed physical constant. It was derived from 1950s data on the caloric value of lost body weight, and later modeling has shown the real number shifts with your starting body composition and how long the deficit continues. A moderate target is usually easier to sustain. Monitor energy, hunger, performance, and weight trend, then make small adjustments instead of dramatic changes.
Frequently Asked Questions
How large should my calorie deficit be?
A moderate deficit of about 15 to 25% below maintenance is generally more sustainable than an aggressive cut, and tends to preserve more muscle mass along the way.
How fast should I expect to lose weight?
A common, sustainable target is roughly 0.5 to 1% of body weight per week. Faster loss is possible but increases the risk of muscle loss and rebound weight regain.
Why did my weight loss stall on the same calories?
As you lose weight, your maintenance calories drop too, since a smaller body burns less energy, and the deficit needed per unit of further loss also shifts as your body composition changes³. Recalculate periodically to keep your deficit accurate.
Is a bigger deficit always better for results?
Not necessarily. Very large deficits often lead to more muscle loss, fatigue, and difficulty sticking to the plan long term.
Sources
A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals, Mifflin et al., 1990
Caloric Equivalents of Gained or Lost Weight, Wishnofsky, 1958
What Is the Required Energy Deficit per Unit Weight Loss?, Hall, 2008
Body Weight Planner, NIH / NIDDK
Calorie Deficit Calculator
Use this calorie deficit calculator to find how many calories to eat each day for your weekly weight-loss goal.
Calculated instantly in your browser — nothing is sent to or stored on our servers.
Alyssa Northrop, MPH, RD
Alyssa Northrop, MPH, RD, is a registered dietitian who earned her MPH in Human Nutrition at the University of Michigan and completed her dietetic internship there.
Medical Disclaimer: This calculator provides a general estimate based on established research and is for educational purposes only, not a substitute for medical advice. Individual results can vary based on health conditions, so consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, exercise, or health routine. Read our full Medical Disclaimer.
How a Calorie Deficit Is Calculated
Weight loss comes down to energy balance: eat fewer calories than you burn, and your body draws on stored energy, including body fat, to make up the difference. This calculator converts a weekly weight-loss goal you choose directly into a daily calorie number, rather than leaving you to guess at the math yourself.
What This Calculator Measures
This calorie deficit calculator gives you a single daily calorie target based on your specific weekly loss goal. If you just want your maintenance number with no deficit applied, use the TDEE Calculator instead.
Step 1: Maintenance Calories (TDEE)
We estimate your Basal Metabolic Rate (BMR) with the Mifflin-St Jeor formula¹, then multiply by your activity level to get your maintenance calories, the amount that keeps your weight stable.
Step 2: Size the Deficit to Your Goal
One kilogram of body weight holds roughly 7,700 calories, a figure that traces back to a 1958 analysis of the caloric equivalents of weight gained or lost²."
Daily deficit = (weekly loss goal in kg × 7,700) ÷ 7
Your target calories are your maintenance calories minus this deficit, never dropping below a safe minimum (1,500 kcal for men, 1,200 kcal for women).
How This Calculator Computes Your Result
Enter your sex, age, height, weight, activity level, and weekly loss goal above. We calculate your maintenance calories, apply the deficit formula, and cap the result at the safe minimum if needed.
Why the 7,700 Figure Is a Starting Point, Not a Law
The 1958 estimate assumed that all lost weight comes from pure fat tissue, an assumption that holds up reasonably well for short-term, moderate deficits but breaks down over longer periods².
A more recent mathematical model of body weight regulation, developed by a researcher at the U.S. National Institutes of Health, the same institute behind the NIH Body Weight Planner tool⁴, found that the actual deficit needed per unit of weight lost shrinks as a person gets leaner, since a larger share of continued loss comes from lean tissue rather than fat once fat stores are reduced³.
In practical terms, this means a fixed 7,700-calorie rule tends to overpredict weight loss the longer a diet continues.
A Note on Accuracy
The 7,700-calorie-per-kg figure is a useful planning estimate, not a fixed physical constant. It was derived from 1950s data on the caloric value of lost body weight, and later modeling has shown the real number shifts with your starting body composition and how long the deficit continues. A moderate target is usually easier to sustain. Monitor energy, hunger, performance, and weight trend, then make small adjustments instead of dramatic changes.
Frequently Asked Questions
How large should my calorie deficit be?
A moderate deficit of about 15 to 25% below maintenance is generally more sustainable than an aggressive cut, and tends to preserve more muscle mass along the way.
How fast should I expect to lose weight?
A common, sustainable target is roughly 0.5 to 1% of body weight per week. Faster loss is possible but increases the risk of muscle loss and rebound weight regain.
Why did my weight loss stall on the same calories?
As you lose weight, your maintenance calories drop too, since a smaller body burns less energy, and the deficit needed per unit of further loss also shifts as your body composition changes³. Recalculate periodically to keep your deficit accurate.
Is a bigger deficit always better for results?
Not necessarily. Very large deficits often lead to more muscle loss, fatigue, and difficulty sticking to the plan long term.
Sources
A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals, Mifflin et al., 1990
Caloric Equivalents of Gained or Lost Weight, Wishnofsky, 1958
What Is the Required Energy Deficit per Unit Weight Loss?, Hall, 2008
Body Weight Planner, NIH / NIDDK