Calorie Deficit Calculator
Find the daily deficit needed to reach a weight goal.
Your daily calories to maintain weight (TDEE).
Results update as you type.
This calculator provides estimates based on population research. Results are not medical advice. Consult a qualified healthcare provider before making health or nutrition decisions.
How it works
A calorie deficit is the gap between the energy you burn and the energy you eat, and it is the fundamental driver of weight loss: eat less than you spend, and your body makes up the difference by drawing on stored fat. A calorie deficit calculator works backwards from a goal, taking the weight you want to lose and the time you have, and telling you how large a daily deficit that requires and what daily calorie intake to aim for. The engine rests on the well-known approximation that a kilogram of body fat stores roughly 7,700 calories, so losing five kilograms means creating a total deficit of about 38,500 calories, spread across your chosen timeframe. Dividing that total by the number of days yields the deficit you need each day, and subtracting it from your maintenance calories, your total daily energy expenditure, gives your target intake. People rely on a calorie deficit calculator to make weight loss concrete and paced rather than a vague intention, and to sanity-check whether a goal is realistic. A safe, sustainable rate is generally about 0.5 to 1 kilogram per week, which usually means a deficit of roughly 500 to 1,000 calories a day. Aggressive deficits risk muscle loss, fatigue and rebound. The 7,700-calorie rule is a useful average, not an exact law, since metabolism adapts as you lose weight, so review your target intake and adjust as progress and appetite change over time.
Daily deficit = (target kg × 7700) ÷ (weeks × 7); target intake = maintenance − daily deficit
The calculation converts a weight goal into an energy goal using the constant that one kilogram of fat holds about 7,700 calories. Multiplying your target loss by 7,700 gives the total energy deficit required. Dividing by the number of days in your timeframe, weeks times seven, spreads that deficit evenly per day. Subtracting the daily deficit from your maintenance calories reveals the intake that should produce the loss at the pace you chose.
Source:NIH / standard energy-balance guidance (≈7,700 kcal per kg fat)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter maintenance calories, target weight loss and timeframe.
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Daily calorie deficit updates instantly as you type — no button to press.
Frequently asked questions
How big a calorie deficit is safe?
Most guidelines suggest a deficit of about 500 to 1,000 calories per day, producing roughly 0.5 to 1 kilogram of loss per week. Going much lower than around 1,200 calories a day for women or 1,500 for men risks nutrient shortfalls, muscle loss and rebound eating. A moderate deficit preserves more muscle and is easier to sustain. If this calculator suggests an extreme deficit, extend your timeframe to keep the daily figure reasonable and healthy.
Is the 7,700 calories per kilogram rule accurate?
It is a widely used approximation, not an exact constant. A kilogram of body fat stores close to 7,700 calories, but real weight change also involves water, glycogen and lean tissue, and metabolism adapts as you lose weight, slowing the rate over time. So actual results often lag the simple prediction, especially in later weeks. Treat the number as a solid starting estimate and adjust based on your measured progress every few weeks.
Why has my weight loss stalled despite a deficit?
Plateaus are common because the body adapts: as you lose weight your maintenance calories fall, shrinking your effective deficit, and metabolism can down-regulate slightly. Water retention, especially with stress, poor sleep or a high-salt day, can also mask fat loss on the scale. Recalculate your maintenance at your new weight, tighten portion tracking, ensure adequate protein and be patient, since the scale often catches up after a whoosh of water loss.
Will a calorie deficit cost me muscle?
It can, but you can limit muscle loss substantially. Keep the deficit moderate rather than extreme, eat plenty of protein, around 1.6 to 2.2 grams per kilogram of body weight, and do regular resistance training to signal your body to preserve muscle. Losing weight too fast, neglecting protein or skipping strength work all increase the share of weight lost as muscle. A slower, protein-rich, strength-supported approach protects lean mass best.
Do I still need to exercise to lose weight?
You can create a deficit through diet alone, but exercise makes it easier and healthier. Activity raises the calories you burn, so you can eat a little more for the same deficit, and resistance training protects muscle while cardio benefits your heart. Exercise also improves mood, sleep and appetite regulation. For lasting results, most people find combining a modest dietary deficit with regular movement more sustainable than relying on either alone.