Weight Loss/Gain Calculator
Calculate timeline and calories for weight goals
Results
Weight Change Projection
⚠️ This calculator is for informational purposes only and should not be used as a substitute for professional medical advice. Always consult with a healthcare provider for medical concerns.
What is Weight Loss/Gain?
Weight loss or gain occurs when you create a calorie deficit (eat less than you burn) or surplus (eat more than you burn). This calculator uses your BMR (Basal Metabolic Rate) and TDEE (Total Daily Energy Expenditure) to determine the calories needed to reach your weight goal. A safe rate of weight loss is 1-2 lbs per week, while weight gain should be gradual (0.5-1 lb per week for muscle gain).
BMR is the calories your body burns at rest for basic functions. TDEE includes BMR plus calories burned through activity and digestion. To lose weight, eat below TDEE. To gain weight, eat above TDEE. The key is creating an appropriate calorie deficit or surplus based on your goals and maintaining it consistently. For tracking exercise calorie burn, see our Calorie Burn Projection Calculator to understand how exercise contributes to your calorie balance.
How to Use This Calculator
Enter your current weight, target weight, activity level, age, gender, and height. The calculator calculates your BMR using the Mifflin-St Jeor equation, determines TDEE based on activity level, calculates calories needed for your goal, estimates time to reach your goal, and provides a recommended weekly rate.
Use the chart to visualize your projected weight change over time. Understanding the timeline helps set realistic expectations and plan your approach to weight loss or gain.
Formula Explained
The calculation uses the Mifflin-St Jeor equation for BMR:
Women: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age) - 161
TDEE = BMR × Activity Multiplier
Activity Multipliers:
- Sedentary: 1.2
- Light: 1.375
- Moderate: 1.55
- Very Active: 1.725
- Extremely Active: 1.9
Weight Change: 3,500 calories = 1 lb
Source: Mifflin-St Jeor Equation for BMR (NIH and Academy of Nutrition and Dietetics)
When to Use This Calculator
Use this calculator to determine calorie needs for weight loss or gain, set realistic timelines for reaching your goal, or understand the relationship between calories, activity, and weight change. It's helpful for anyone starting a weight management program who wants to create a data-driven plan.
Individuals and healthcare providers use BMR and TDEE calculations to create personalized nutrition plans, set realistic weight goals, and understand the calorie balance needed for sustainable weight management. For body composition goals, use our Body Fat Percentage Change Calculator to track fat loss while preserving muscle.
Tips for Best Results
- Start with a moderate deficit: For weight loss, start with a 500 calorie daily deficit (1 lb/week). This is sustainable and preserves muscle mass. Don't go below 1,200 calories (women) or 1,500 calories (men) without medical supervision.
- Track accurately: Use a food scale and tracking app for accurate calorie counting. Many people underestimate portions. Accurate tracking is essential for success.
- Prioritize protein: During weight loss, aim for 0.8-1 gram of protein per pound of body weight. Higher protein preserves muscle mass, increases satiety, and supports metabolism.
- Include strength training: Strength training preserves muscle mass during weight loss, which helps maintain metabolism and improves body composition. Don't just focus on cardio.
- Be patient and consistent: Weight loss isn't linear. You'll have weeks with no change or even slight increases. Focus on long-term trends, stay consistent, and adjust as needed. Sustainability is key.
- Track exercise calories: Use our Calorie Burn Projection Calculator to understand how different exercises contribute to your calorie deficit and weight loss goals.
Frequently Asked Questions
What is BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at rest for basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) is your total daily calorie burn including BMR, activity, and digestion. TDEE = BMR × Activity Multiplier. To lose weight, eat below TDEE. To gain weight, eat above TDEE.
What's a safe rate of weight loss?
A safe rate of weight loss is 1-2 lbs per week (0.5-1% of body weight). This requires a 500-1000 calorie daily deficit. Faster loss may cause muscle loss, metabolic slowdown, and is harder to sustain. Slower loss (0.5-1 lb/week) is more sustainable and preserves muscle mass better.
How do I calculate my calorie deficit?
Calorie deficit = TDEE - Calories Consumed. To lose 1 lb per week, create a 500 calorie daily deficit (3,500 calories = 1 lb). To lose 2 lbs per week, create a 1,000 calorie daily deficit. However, don't go below 1,200 calories (women) or 1,500 calories (men) without medical supervision.
Can I lose weight without counting calories?
Yes, but tracking helps ensure accuracy. You can lose weight by eating whole foods, controlling portions, increasing protein and fiber, and staying active. However, many people underestimate calories consumed and overestimate calories burned. Tracking provides objective data.
Why is my weight loss slowing down?
Weight loss often slows due to metabolic adaptation (your body burns fewer calories as you lose weight), water retention, muscle gain (if strength training), or inaccurate tracking. Plateaus are normal. Focus on long-term trends, ensure you're in a deficit, and be patient. Consider a diet break if stalled for weeks.
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