Weight Loss Calculator (Canada)
✅ Dietitian-Reviewed | ✅ Mifflin-St Jeor Equation | ✅ Updated July 2026
Find your exact daily calorie target, calorie deficit, weekly weight loss rate, and precise timeline to reach your goal weight — backed by the same science used by the NIH Body Weight Planner. Takes under 60 seconds.
How to Use This Weight Loss Calculator
Getting your personalized weight loss plan takes under 60 seconds:
- Enter your current weight — toggle between lbs and kg.
- Enter your goal weight — a safe starting target is 5–10% of your current body weight.
- Add your height and age — these determine your Basal Metabolic Rate (BMR).
- Select your activity level — when in doubt, go one level lower than you think.
- Set a target date or weekly rate — the calculator works both ways.
Your results instantly show your daily calorie target, weekly projected loss, estimated weeks to goal, and weight loss percentage.
The Science Behind Your Results
This calculator uses the Mifflin-St Jeor equation — the most accurate formula for estimating resting energy expenditure, validated in peer-reviewed research and recommended by the Academy of Nutrition and Dietetics.
How Your Calorie Target Is Calculated
- BMR (Basal Metabolic Rate): How many calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and organs functioning.
- TDEE (Total Daily Energy Expenditure): Your BMR multiplied by an activity factor — the actual calories you burn each day.
- Calorie Deficit: Eat less than your TDEE. A deficit of 500 cal/day ≈ 1 lb of fat lost per week. A 1,000 cal/day deficit ≈ 2 lbs/week.
The 3,500-Calorie Rule — And Its Limits
Cutting 3,500 calories ≈ losing 1 pound is a useful estimate, but the NIDDK confirms real-world weight loss is not perfectly linear. As you lose weight, your TDEE decreases — which is why results slow down over time. This calculator accounts for that adaptation.
Safe Rate of Weight Loss
The CDC recommends losing 0.5 to 2 pounds (0.25–1 kg) per week. This range:
- Preserves muscle mass (critical for long-term metabolism)
- Is sustainable without extreme hunger
- Reduces the risk of nutrient deficiencies
- Produces results that are far more likely to last
What Is Weight Loss Percentage — And Why Does It Matter?
Raw pounds lost tells only part of the story. Weight loss percentage shows how much of your starting body weight you've lost — and it's the metric doctors and clinical researchers actually use.
The Formula
Example Calculations
| Starting Weight | Current Weight | Lbs Lost | Weight Loss % |
|---|---|---|---|
| 200 lbs | 190 lbs | 10 lbs | 5.0% |
| 200 lbs | 180 lbs | 20 lbs | 10.0% |
| 250 lbs | 212 lbs | 38 lbs | 15.2% |
Clinical Benchmarks
- 5% body weight loss — Measurable improvements in blood pressure, blood sugar, and cholesterol (CDC-recognized threshold)
- 10% body weight loss — Significant reduction in risk for Type 2 diabetes, sleep apnea, and cardiovascular disease
- 15–20% loss — Often required for meaningful joint pain relief and sleep apnea resolution
Related Calculators
- Calorie Calculator — Find your daily maintenance calories
- TDEE Calculator — Calculate Total Daily Energy Expenditure
- BMI Calculator — Check your Body Mass Index
- Body Fat Calculator — Estimate your body fat percentage
- Protein Calculator — Daily protein target to preserve muscle while losing fat
Frequently Asked Questions
How do I calculate my weight loss percentage?
Subtract your current weight from your starting weight, divide by your starting weight, then multiply by 100. Example: starting at 200 lbs, now 185 lbs → ((200−185)÷200)×100 = 7.5%. Or use our step-by-step guide.
How many calories do I need to cut to lose 1 pound per week?
A deficit of approximately 500 calories per day (3,500 calories/week) produces roughly 1 lb of fat loss per week. Actual results vary based on your starting weight, metabolism, and muscle mass. Use the calculator above for your personalized number.
What is a healthy rate of weight loss?
The CDC recommends 0.5 to 2 pounds per week. Faster loss increases the risk of muscle loss, nutrient deficiencies, and weight regain.
How long does it take to lose 20 pounds?
At 1 lb/week: approximately 20 weeks (5 months). At 1.5 lbs/week: about 13–14 weeks. Enter your stats in the calculator above to get your exact personalized timeline.
Why did my weight loss stall?
As you lose weight, your TDEE decreases — your body burns fewer calories doing the same activities. This is normal. Reassess your calorie target every 4–6 weeks using this calculator with your updated current weight.
Is a 1,000 calorie deficit per day safe?
A 1,000 calorie daily deficit (≈2 lbs/week) is at the upper limit of what is clinically considered safe for most adults and should only be pursued under medical supervision for people with BMI over 30. For most people, 500–750 cal/day deficit is both effective and sustainable.
What is the difference between BMR and TDEE?
BMR is the calories your body burns at complete rest. TDEE is your BMR multiplied by your activity level — the actual calories you burn each day. Your weight loss target is always calculated from TDEE, not BMR.
Should I track calories or just eat healthy?
Both approaches work, but research shows that awareness of calorie intake significantly improves weight loss outcomes. You don't need to count every calorie forever, but understanding your approximate intake during the initial phase helps calibrate habits for long-term success.
Medically Reviewed By
Dr. Sarah Jenkins, RD — Clinical Dietitian & Weight Management Specialist
Dr. Jenkins has over 15 years of experience in clinical nutrition and metabolic health, specializing in evidence-based weight loss strategies.
Last reviewed: July 2026 | Sources: NIDDK Body Weight Planner · CDC Healthy Weight Guidelines