Calorie Calculator

Calorie Calculator

Knowing how many calories you need each day is the foundation of any effective weight management plan. This calculator uses your age, gender, height, weight, and activity level to estimate your Basal Metabolic Rate (BMR) and maintenance calories — the number you need to keep your weight stable. From there it generates targets for mild weight loss (-0.5 lb/week), standard weight loss (-1 lb/week), and weight gain, so you have a concrete number to build your diet around rather than guessing.

How Daily Calories Are Calculated

This calculator uses the Mifflin-St Jeor equation, which has been validated in multiple studies as the most accurate BMR formula for the general population.

• Men: BMR = (10 x weight in kg) + (6.25 x height in cm) — (5 x age) + 5
• Women: BMR = (10 x weight in kg) + (6.25 x height in cm) — (5 x age) — 161

Your BMR is then multiplied by an activity factor to produce your Total Daily Energy Expenditure (TDEE), which equals your maintenance calories:

Weight change targets are then set by adjusting your maintenance figure: subtract 250 calories for mild loss (about 0.5 lb/week), subtract 500 for standard loss (about 1 lb/week), and add 300-500 for gradual weight gain.

Worked Examples

Example 1 — Sedentary office worker trying to lose weight. Marcus is a 32-year-old male, 5’10” (178 cm), 195 lbs (88.5 kg), with a desk job and no regular exercise. His BMR calculates to approximately 1,884 calories. Multiplied by the sedentary factor of 1.2, his maintenance is 2,261 calories per day. To lose 1 pound per week, he targets 1,761 calories — a realistic number he can hit without extreme restriction.

Example 2 — Active woman maintaining weight. Priya is a 27-year-old female, 5’5” (165 cm), 135 lbs (61.2 kg), who runs 4 days per week and lifts twice weekly. Her BMR is roughly 1,400 calories. At a moderately active multiplier of 1.55, her maintenance is approximately 2,170 calories per day. She eats around this number and her weight stays stable, confirming the estimate is close to her true TDEE.

Example 3 — Older adult trying to gain muscle. Carol is a 55-year-old female, 5’6” (168 cm), 148 lbs (67.1 kg), doing resistance training 3 days per week. Her BMR is approximately 1,349 calories, and at lightly active (1.375), her maintenance is around 1,855 calories. To support muscle gain, she targets 2,100-2,200 calories daily — a modest surplus that minimizes fat gain while fueling muscle synthesis.

Reference Table

When to Use This Calculator

• Starting a fat loss phase — get a specific calorie target instead of guessing or using generic “1,200 calorie” advice that may not match your body
• Breaking a weight loss plateau — recalculate after losing 15+ pounds, since your maintenance calories have likely dropped 100-200 calories from where they started
• Bulking for muscle gain — establish your true maintenance before adding a 300-500 calorie surplus to minimize unnecessary fat gain
• Comparing activity scenarios — see exactly how much adding a 30-minute daily walk or gym session changes your daily energy needs
• Planning a recomposition — understand whether your current intake is truly a deficit or closer to maintenance before making changes to your routine

Common Mistakes to Avoid

1. Overestimating activity level. Most people who work desk jobs and exercise 3-4 times per week are “lightly active,” not “moderately active.” Selecting the wrong multiplier inflates your maintenance by 200-300 calories, which can stall fat loss entirely. Start one level lower than you think you need and adjust based on results.

2. Not recalculating as weight changes. Every 10-15 pounds of weight lost, your calorie needs decrease. A 200-pound person losing weight to 175 pounds may see their maintenance drop by 150-200 calories. If you are still eating your original deficit calories, you may have eliminated your deficit entirely.

3. Treating the number as exact. The Mifflin-St Jeor equation is accurate within roughly 10% for most people. Your actual TDEE could be 150-250 calories above or below the estimate. Treat the output as a starting point, track your weight for 2-3 weeks, and adjust by 100-150 calories if results do not match expectations.

4. Going too low, too fast. Deficits beyond 1,000 calories per day cause muscle loss, nutrient deficiencies, and metabolic adaptation that makes long-term fat loss harder. Never drop below 1,200 cal/day for women or 1,500 cal/day for men without direct supervision from a healthcare provider.

Understanding Your Results

Your BMR is what your body burns at complete rest — breathing, circulation, organ function. This number forms your floor. The maintenance calories figure is what you need to eat to keep your weight exactly where it is. Eating below maintenance puts you in a deficit; eating above puts you in a surplus.

The weight loss targets assume 1 pound of fat = approximately 3,500 calories, so a 500-calorie daily deficit yields roughly 1 pound per week. In practice, weight loss is not perfectly linear — water retention, hormonal fluctuations, and muscle changes all affect the scale. Weigh yourself at the same time each morning under the same conditions and look at the 7-day average rather than any single reading.

If your maintenance comes out lower than expected — say, under 1,600 calories for a moderately active person — that is worth discussing with a healthcare provider, as it may reflect an underlying metabolic issue.

Tips

1. A 500 cal/day deficit equals roughly 1 lb of fat loss per week — start here before considering anything more aggressive
2. Be honest about your activity level; most people overestimate and should start with “lightly active” then adjust based on 2-3 weeks of real data
3. Recalculate every 10-15 pounds of weight change — your calorie needs decrease as you lose, which is why plateaus happen
4. Pair this calculator with the Macro Calculator to convert your calorie target into a specific protein, carb, and fat plan
5. If weight is not moving after 3 weeks, reduce calories by 100-150 per day rather than making a large cut all at once
6. Strength training during a deficit helps preserve muscle — adding even 2 sessions per week makes a meaningful difference in body composition outcomes