Example 1
30-year-old woman, moderately active
At 5'5" and 150 lb, maintenance is about 2,150 calories; weight loss is about 1,650.
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Calorie Calculator
Estimate your daily calorie needs for maintenance, weight loss, or weight gain, plus your BMR and macronutrient targets.
Your details
We use the Mifflin-St Jeor equation to estimate your calorie needs.
yrs
ft
in
lbs
Daily calories to maintain weight
2,689 cal
Weight loss (500 cal deficit)
2,189 cal
Fast weight loss (1,000 cal deficit)
1,689 cal
Weight gain (500 cal surplus)
3,189 cal
BMR (basal metabolic rate)
1,735 cal
Fast weight loss targets below 1,200 calories per day for women or 1,500 for men are generally not recommended without medical supervision.
Macronutrient recommendations
Based on a balanced 30% protein / 40% carbohydrate / 30% fat split of each daily calorie target.
| Goal | Calories/day | Protein (g) | Carbohydrates (g) | Fat (g) |
|---|---|---|---|---|
| Maintain weight | 2,689 | 202 | 269 | 90 |
| Weight loss (−500) | 2,189 | 164 | 219 | 73 |
| Fast weight loss (−1,000) | 1,689 | 127 | 169 | 56 |
| Weight gain (+500) | 3,189 | 239 | 319 | 106 |
Disclaimer
These calculations are estimates based on established formulas. Consult a healthcare professional or registered dietitian for personalized nutrition advice.
Calculator guide
How It Works
The calculator estimates your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, which uses weight, height, age, and sex to estimate the calories your body burns at complete rest. It then multiplies BMR by an activity factor to estimate total daily energy expenditure, the calories needed to maintain your current weight. Weight loss and gain targets are built by subtracting or adding calories from that maintenance figure.
Age matters because metabolism slows gradually over time. Sex changes the equation because average body composition differs. Height and weight determine how much energy your body needs to function. Activity level, from sedentary to very active, often moves the result more than any other input, so choose honestly. Understanding your numbers lets you plan meals that fit your goals and budget, and it is a useful starting point that you can adjust after a few weeks of tracking real results on the scale.
What the Numbers Mean
- Maintain
- Calories to keep weight steady. A high number usually reflects size or activity.
- Weight loss
- About 500 fewer calories daily, roughly one pound a week.
- Fast weight loss
- A larger deficit; harder to sustain and not ideal long term.
- Weight gain
- A surplus for building mass, best paired with strength training.
- BMR
- Calories burned at rest. Eating far below it is generally discouraged.
Common Scenarios
Example 2
45-year-old man, sedentary
At 5'11" and 200 lb, maintenance is around 2,250 calories.
Example 3
Becoming more active
Moving from sedentary to moderate activity can add 300 to 400 maintenance calories.
Frequently Asked Questions
How does this calculator determine my daily calorie needs?
The calculator uses age, weight, height, sex, and activity level to estimate total daily energy expenditure. That number reflects the calories needed to maintain current weight.
How many calories should I cut to lose weight?
A deficit of 500 calories per day typically leads to about one pound of weight loss per week. The calculator shows how different deficit amounts affect the expected timeline.
Does activity level significantly change the calorie estimate?
Activity level has a substantial effect, since more active individuals burn more calories daily and require higher intake to maintain weight. Selecting an accurate activity level improves the estimate's reliability.
Should calorie needs get recalculated over time?
Recalculating periodically makes sense since weight changes, age, and activity level all shift calorie needs over time. Checking every few months keeps the estimate accurate.
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