Wondering how many calories you burn in a 45-minute workout? This calculator estimates calorie expenditure for a wide range of activities — from brisk walking and cycling to yoga and low-impact aerobics — based on your body weight and the activity's metabolic equivalent (MET) value.
Simply select your activity, enter your weight, and choose your preferred unit (kg or lb). The tool instantly shows your estimated calories burned, along with a breakdown of the calculation and a comparison to a 30-minute session. It's perfect for planning gentle fitness routines, tracking progress, or comparing different low-impact exercises.
Whether you're a beginner building a routine or a seasoned exerciser fine-tuning your workouts, this calculator gives you a quick, reliable estimate to support your goals.
⚙️ Calorie Burn Estimator
How to Use This Tool
Using the calculator is straightforward:
- Select your activity from the dropdown. Each activity has a MET value that represents its intensity.
- Enter your body weight in kilograms or pounds.
- Click Calculate to see your estimated calories burned over 45 minutes.
You can also use the quick-fill buttons to instantly set a common weight, then adjust if needed. The result shows the total calories, the activity and MET value used, and a comparison to a 30-minute session.
How It Works
The calculation uses the standard MET (Metabolic Equivalent of Task) formula:
Calories per minute = (MET × 3.5 × weight in kg) / 200
Then multiply by the duration in minutes (45 in this case).
MET values are assigned by the Compendium of Physical Activities, a widely used research resource. For example, walking at 3 mph has a MET of 3.0, while cycling at 12–14 mph has a MET of 6.8. The formula estimates the energy cost of an activity relative to resting metabolic rate.
Worked Examples
Example 1: A 70 kg person does low-impact aerobics (MET 4.5) for 45 minutes.
Calories = (4.5 × 3.5 × 70) / 200 × 45 = 1,102.5 / 200 × 45 = 5.5125 × 45 ≈ 248 kcal
Example 2: A 155 lb person (about 70.3 kg) cycles at 12–14 mph (MET 6.8) for 45 minutes.
Calories = (6.8 × 3.5 × 70.3) / 200 × 45 = 1,673.14 / 200 × 45 = 8.3657 × 45 ≈ 376 kcal
Tips & Best Practices
- For weight loss, aim for a consistent calorie deficit, but don't rely solely on exercise estimates — combine with a balanced diet.
- Use a heart rate monitor or fitness tracker to get a more personalized estimate, as your actual burn may vary.
- If you're new to exercise, start with lower-intensity activities like walking or yoga and gradually increase intensity.
- Remember that muscle mass, age, and fitness level affect your true metabolic rate.
Factors Affecting Accuracy
The MET formula provides a good estimate, but individual results vary. Factors such as your body composition, age, gender, and how efficiently you perform the movement all influence actual calorie burn. The MET values are averages from research studies and may not perfectly match your effort level. For example, a vigorous yoga session might burn more than the standard Hatha yoga value.
Frequently Asked Questions
Is 45 minutes enough for a good workout?
Yes, 45 minutes is a solid duration for most people. It's long enough to burn a meaningful number of calories and improve cardiovascular fitness, especially if you exercise most days of the week.
Can I use this calculator for other durations?
Yes, you can adjust the formula manually. Simply multiply the per-minute result by your desired duration. For example, for 30 minutes, use the comparison shown in the result.
Why does the calculator ask for weight in kg or lb?
Because the formula uses weight in kilograms, the calculator converts pounds automatically. This makes it easy for users in any country.
What is MET?
MET stands for Metabolic Equivalent of Task. One MET is the energy cost of sitting quietly. Activities are rated relative to this baseline — for example, walking at 3 mph is 3 METs, meaning it burns three times the energy of resting.
Additional Resources
For more detailed MET values and research, visit the Compendium of Physical Activities. You can also explore our other calorie calculators for different activities and durations.