📉 Calorie Deficit Calculator
By ToolNimba Health Team · Reviewed by ToolNimba Editorial Review, health content · Updated 2026-06-19
This calculator gives an estimate, not medical or dietary advice. Safe, sustainable weight loss depends on your body composition, health conditions, medications and lifestyle. Do not eat below the safe calorie floors flagged here without supervision. Speak to a doctor or registered dietitian before starting a diet, especially if you are pregnant, under 18, or managing a health condition.
A calorie deficit is the gap between the calories you burn and the calories you eat, and it is the engine behind every diet that works. Enter your maintenance calories (your TDEE) and how much weight you want to lose each week, in pounds or kilograms, and this calculator shows the daily deficit you need and the calorie target to aim for. It uses the standard energy values for body fat: about 3,500 kcal per pound and about 7,700 kcal per kilogram.
What is the Calorie Deficit Calculator?
Weight loss comes down to energy balance. Your body uses a certain number of calories each day to stay alive and move around, a figure called your Total Daily Energy Expenditure (TDEE) or maintenance calories. Eat exactly that and your weight holds steady. Eat less and your body makes up the shortfall by burning stored energy, mostly fat, so you lose weight. That shortfall is the calorie deficit.
To turn a weight loss goal into a daily number we use the energy stored in body fat. A pound of fat holds roughly 3,500 calories and a kilogram holds roughly 7,700 calories. So to lose one pound a week you need a total weekly deficit of about 3,500 calories, which spread over seven days is 500 calories a day. To lose half a kilogram a week you need about 3,850 calories over the week, or 550 a day. The calculator divides your weekly goal by seven to give the daily deficit, then subtracts it from your maintenance to give your eating target.
The 3,500-calorie rule is a useful planning tool, not a perfect law. Real fat loss is slower than the maths suggests over long periods because your metabolism adapts as you get lighter and you tend to move a little less on fewer calories. Some early weight change is also water, not fat. Treat the target as a sensible starting point, track your weight over two to three weeks, and adjust the number based on what the scale actually does rather than trusting the formula blindly.
When to use it
- Turning a goal like "lose a pound a week" into a concrete daily calorie number to eat.
- Checking whether the deficit behind an aggressive weight loss target is realistic or dangerously steep.
- Comparing how a slower 0.5 lb a week plan and a faster 2 lb a week plan change your daily calories.
- Setting a sustainable eating target once a separate TDEE calculator has given you your maintenance calories.
How to use the Calorie Deficit Calculator
- Enter your maintenance calories (TDEE). If you do not know it, work it out first with a TDEE calculator.
- Type how much weight you want to lose each week.
- Choose whether that goal is in pounds or kilograms.
- Read your daily calorie target, the daily deficit, and the weekly deficit below.
- Heed any warning if the target drops below the safe calorie floor.
Formula & method
Worked examples
Maintenance of 2,500 kcal, aiming to lose 1 lb per week.
- Weekly deficit = 1 x 3500 = 3500 kcal
- Daily deficit = 3500 ÷ 7 = 500 kcal
- Daily target = 2500 − 500 = 2000 kcal
Result: Eat about 2,000 kcal/day, a 500 kcal daily deficit
Maintenance of 2,200 kcal, aiming to lose 0.5 kg per week.
- Weekly deficit = 0.5 x 7700 = 3850 kcal
- Daily deficit = 3850 ÷ 7 = 550 kcal
- Daily target = 2200 − 550 = 1650 kcal
Result: Eat about 1,650 kcal/day, a 550 kcal daily deficit
Maintenance of 2,800 kcal, aiming for an aggressive 2 lb per week.
- Weekly deficit = 2 x 3500 = 7000 kcal
- Daily deficit = 7000 ÷ 7 = 1000 kcal
- Daily target = 2800 − 1000 = 1800 kcal
Result: Eat about 1,800 kcal/day, a steep 1,000 kcal daily deficit
Daily deficit needed for common weekly weight loss goals
| Weekly goal | Weekly deficit | Daily deficit |
|---|---|---|
| 0.5 lb (0.23 kg) | 1,750 kcal | 250 kcal |
| 1 lb (0.45 kg) | 3,500 kcal | 500 kcal |
| 1.5 lb (0.68 kg) | 5,250 kcal | 750 kcal |
| 2 lb (0.91 kg) | 7,000 kcal | 1,000 kcal |
| 0.5 kg (1.1 lb) | 3,850 kcal | 550 kcal |
| 1 kg (2.2 lb) | 7,700 kcal | 1,100 kcal |
Commonly cited minimum daily calorie floors
| Group | Suggested floor | Note |
|---|---|---|
| Adult women | 1,200 kcal/day | Below this is hard to meet nutrient needs |
| Adult men | 1,500 kcal/day | Below this is hard to sustain safely |
| Anyone, below floor | Medical supervision | Very low calorie diets need a clinician |
Common mistakes to avoid
- Setting too aggressive a deficit. Chasing 2 lb or more a week often pushes the target below your needs, costing muscle and energy and making the diet hard to stick to. A 500 to 750 kcal daily deficit is steadier and more sustainable for most people.
- Eating below the safe calorie floor. Dropping under about 1,200 kcal/day for women or 1,500 for men makes it difficult to get enough protein, vitamins and minerals. If your target lands there, lose weight more slowly or get professional guidance.
- Trusting the 3,500-calorie rule forever. The rule predicts short-term loss well but overestimates it over months, because your metabolism adapts as you get lighter. Recalculate your maintenance and deficit every few kilograms.
- Adding back exercise calories. If your maintenance figure already includes your usual activity, eating extra to "replace" calories burned in a workout shrinks or erases the deficit. Build activity into your TDEE instead of bolting it on afterward.
Glossary
- Calorie deficit
- Eating fewer calories than you burn, so the body draws on stored energy and you lose weight over time.
- Maintenance calories
- The daily intake that keeps your weight stable; your Total Daily Energy Expenditure or TDEE.
- TDEE
- Total Daily Energy Expenditure: all the calories you burn in a day from rest, digestion, daily movement and exercise.
- 3,500-calorie rule
- The estimate that a pound of body fat stores about 3,500 kcal, used to plan weight loss; a kilogram is about 7,700 kcal.
- Calorie floor
- A commonly cited minimum daily intake (about 1,200 kcal for women, 1,500 for men) below which dieting unsupervised is risky.
Frequently asked questions
How big a calorie deficit do I need to lose weight?
To lose about one pound of fat a week you need a total weekly deficit of roughly 3,500 calories, which is 500 calories a day. For one kilogram a week the figure is about 7,700 calories a week, or 1,100 a day. This tool turns your weekly goal into the daily deficit for you.
Is a 500 calorie deficit enough to lose weight?
Yes. A daily deficit of 500 calories targets roughly one pound (0.45 kg) of fat loss a week, which is a widely recommended, sustainable pace. It is large enough to see steady progress without the muscle loss and fatigue that come with very steep deficits.
How many calories should I eat to lose weight?
Subtract your daily deficit from your maintenance calories. For example, if you maintain on 2,500 kcal and want to lose a pound a week, eat about 2,000 kcal a day. Avoid going below the safe floor of about 1,200 kcal for women or 1,500 for men.
What is the lowest number of calories I should eat?
As a general guide, women should not drop below about 1,200 kcal a day and men below about 1,500, because it becomes hard to meet nutrient needs. Very low calorie diets below these levels should only be followed under medical supervision.
Why am I losing weight slower than the calculator predicts?
The 3,500-calorie rule predicts short-term loss well but overestimates it over months. As you get lighter your metabolism falls, you may move a little less, and tracking errors creep in. Recalculate your maintenance every few kilograms and adjust your deficit.
Does this calorie deficit calculator store my data?
No. Everything is calculated in your browser. Nothing you enter is sent to a server or saved anywhere, so your figures stay private to you.
Sources
- Counting calories: Get back to weight loss basics , Mayo Clinic
- Healthy weight loss , U.S. Centers for Disease Control and Prevention