Calorie Deficit Calculator
Calculate the Right Calorie Deficit for Your Goals
Need to use Calorie Deficit Calculator right now?
A calorie deficit only makes sense relative to an accurate maintenance calorie baseline — without that baseline, a deficit target is just a guess. This tool calculates your actual maintenance calories first, then shows exactly what common deficit targets look like from there.
Features
- Runs entirely in your browser
- Privacy-first — your data is never uploaded
- Real-time, instant results
- 100% free, no sign-up required
- Works on desktop, tablet, and mobile
- No installation needed
Who uses this tool?
About Calorie Deficit Calculator
Total daily calorie needs — how much you actually burn in a day, including all activity, not just resting metabolism — is the number that matters for weight management, and it depends on combining your BMR (Basal Metabolic Rate) with an activity level multiplier that accounts for exercise, daily movement, and lifestyle.
This tool calculates BMR using the Mifflin-St Jeor equation, then multiplies it by one of five standard activity level factors, ranging from sedentary (little to no exercise, multiplier 1.2) up to extremely active (intense daily training plus a physically demanding job, multiplier 1.9). The result is your estimated maintenance calories — the amount needed to keep your current weight stable.
From that maintenance number, the tool also shows calorie targets for common weight goals: a 250 or 500 calorie daily deficit for mild or standard weight loss, and a 250 or 500 calorie daily surplus for mild or standard weight gain. A pound of body fat represents roughly 3,500 calories, which is why a 500-calorie daily deficit is commonly associated with roughly one pound of weight loss per week — though this is a simplified rule of thumb, not an exact guarantee for every individual.
Choosing the right activity level honestly is the biggest source of error in this kind of calculation — most people tend to overestimate their actual activity level, which leads to an inflated calorie target. If weight isn't changing as the numbers here would predict over several weeks, that's a signal to reassess the activity level assumption or actual intake tracking accuracy, not necessarily a sign the formula itself is wrong.
How it works
- Enter your sex, age, height, and weight. Used to calculate your BMR as the baseline.
- Select your activity level honestly. This is the single biggest factor affecting accuracy.
- View maintenance calories and goal-based targets. Mild and standard deficit or surplus targets shown alongside maintenance.
Examples
Maintenance calories for a moderately active person
Input
Male, age 30, 175 cm, 70 kg, moderately active (×1.55)
Output
Maintenance: 2,556 calories/day