Calorie Deficit & Surplus Calculator
Calculate your daily calorie deficit for weight loss or calorie surplus for weight gain. Get personalized recommendations, realistic timelines, and science-based meal plans. Track. Learn. Improve.
Weight Change Timeline
How to Achieve Your Goal
Tips for Success
- Track your food: Use a food diary or app to monitor your calorie intake accurately.
- Stay hydrated: Drink plenty of water throughout the day to support metabolism.
- Eat protein: Include protein in every meal to maintain muscle mass during weight changes.
- Be consistent: Small, consistent changes lead to lasting results.
- Allow flexibility: Plan for occasional treats within your calorie budget.
Note: This calculator provides estimates based on the Mifflin-St Jeor equation and established scientific formulas. Individual results may vary due to factors like genetics, hormones, and medical conditions. Consult a healthcare professional before starting any weight management program, especially if you have underlying health conditions.
Get Your Personalized Plan
Download a comprehensive PDF with your calorie plan, timeline, and recommendations
Frequently Asked Questions
A calorie deficit occurs when you burn more calories than you consume, forcing your body to use stored energy (fat) for fuel, leading to weight loss. A calorie surplus occurs when you consume more calories than you burn, providing extra energy for weight and muscle gain. The principle is based on the first law of thermodynamics - energy cannot be created or destroyed, only transformed.
For weight loss: A moderate deficit of 500-750 calories per day typically leads to 1-1.5 pounds lost per week. For weight gain: A surplus of 300-500 calories per day typically leads to 0.5-1 pound gained per week. These ranges are considered safe and sustainable by nutrition professionals and are based on the principle that 1 pound of fat equals approximately 3,500 calories.
A combination of both diet and exercise is most effective and sustainable. Research shows that diet typically accounts for 70-80% of weight loss, while exercise provides 20-30%. Exercise also helps preserve muscle mass, improves metabolic health, and provides additional benefits like improved cardiovascular health, better mood, and increased bone density.
This calculator uses the Mifflin-St Jeor equation, which is considered one of the most accurate formulas for estimating Total Daily Energy Expenditure (TDEE). While accurate for most people, individual metabolic rates can vary by 10-15% due to factors like genetics, hormones, muscle mass, and metabolic adaptations. Use the results as a starting point and adjust based on actual results over 2-3 weeks.
Yes, eating too few calories can slow your metabolism, cause muscle loss, lead to nutrient deficiencies, and trigger adaptive thermogenesis. Women should generally not go below 1,200 calories per day, and men should not go below 1,500 calories per day without medical supervision. Very low-calorie diets can also cause fatigue, irritability, and make it harder to maintain weight loss long-term.
Weight loss plateaus are normal and occur due to metabolic adaptation. As you lose weight, your body requires fewer calories to maintain basic functions, and your metabolism may slow down by 10-15%. Additionally, you may lose water weight initially, making later progress seem slower. This is why recalculating your calorie needs every 10-15 pounds is important.
Recalculate your calorie needs every 10-15 pounds of weight loss, every 4-6 weeks, or if your activity level changes significantly. As you lose weight, your body requires fewer calories to maintain its basic functions (BMR decreases), so your calorie targets need adjustment to continue seeing progress.
If you're not losing weight after 2-3 weeks of consistent tracking: 1) Double-check food tracking accuracy and portion sizes, 2) Look for hidden calories in drinks, condiments, and cooking oils, 3) Reassess your activity level and exercise intensity, 4) Consider water retention from stress, sleep, or hormonal changes, 5) You may need to adjust your deficit slightly or consult a healthcare professional or registered dietitian.
