Generator Size Calculator for Home
Determine the perfect generator size for your household appliances
Home Generator Size Calculator
Estimate your home's power requirements
Results:
Required Running kVA: 0.00
Required Starting kVA: 0.00
Recommended Generator Size (kVA): 0.00
How to Use the Calculator
Step-by-Step Guide
- Enter the "Total Running Watts" for all continuous appliances.
- Input the "Largest Starting Watts" for the single appliance with the highest surge.
- Provide the "Voltage (V)" of your home's electrical system.
- Adjust the "Power Factor (PF)" if known (default 0.8 for generators).
- Click "Calculate" to see the recommended generator size.
Understanding Watts
- Running Watts: The continuous power an appliance needs to operate.
- Starting Watts: The extra burst of power an appliance (especially with motors) needs to start up.
- Always consider both for accurate generator sizing.
Tips for Accuracy
- List all appliances you plan to power.
- Find their running and starting wattages (usually on labels or manuals).
- Sum up running watts for all appliances.
- Identify the single appliance with the highest starting watts.
Generator Sizing Fundamentals
Running vs. Starting Power
Generators must handle both continuous running loads and momentary starting (surge) loads. Motorized appliances often require significantly more power to start than to run.
Understanding kVA
- kVA (kilo-Volt-Amperes) is apparent power, representing the total power a generator can produce.
- kW (kilowatts) is real power, the actual power used by appliances.
- kVA = kW / Power Factor. Generators are typically rated in kVA.
Key Formulas:
Required Running kVA = Total Running Watts / (PF × 1000)
Required Starting kVA = (Total Running Watts + Largest Starting Watts) / (PF × 1000)
Recommended Generator Size (kVA) = Max(Required Running kVA, Required Starting kVA)
Calculation Formulas
Required Running kVA:
kVA = W_running / (PF × 1000)
Required Starting kVA:
kVA = (W_running + W_starting) / (PF × 1000)
Recommended Generator Size:
Max(Running kVA, Starting kVA)
Example Calculation
Home Power Needs:
Total Running Watts: 5000W
Largest Starting Watts: 2000W (e.g., for a refrigerator)
Voltage: 240V
Power Factor: 0.8
Required Running kVA = 5000 / (0.8 × 1000) = 6.25 kVA
Required Starting kVA = (5000 + 2000) / (0.8 × 1000) = 8.75 kVA
Recommended Generator Size = Max(6.25 kVA, 8.75 kVA) = 8.75 kVA
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