The Whole House Generator Size Calculator helps you determine the appropriate size generator needed to power your entire home during an outage. By inputting the power requirements of your household appliances, the calculator provides an accurate recommendation for a generator that can handle your home’s total power demand, including a safety margin to account for unexpected loads.
Formula of Whole House Generator Size Calculator
To determine the appropriate size for a whole house generator, follow this detailed formula:
Convert Amps to Watts if Needed
If the power is given in amps, convert it to watts using this formula:
Watts = Amps * Volts
Calculate the Total Running Power Requirement
Add the running watts of all the appliances you want to power at the same time.
Calculate the Total Starting Power Requirement
Add the starting watts of appliances with higher starting requirements like motors or compressors.
Consider the Higher of Running and Starting Power Requirements
Use the higher value between the total running and starting power requirements for your calculations.
Add a Safety Margin
Add a 20 to 25 percent safety margin to ensure the generator can handle unexpected loads.
Detailed Formula
Total Running Power = Sum of Running Watts of Each Appliance
Total Starting Power = Sum of Starting Watts of Each Appliance
Total Power Requirement = Higher of Total Running Power and Total Starting Power
Recommended Generator Size = Total Power Requirement * 1.25
Pre-Calculated Table for Common Household Needs
Here is a table with common power requirements for easy reference:
| Appliance | Running Watts | Starting Watts | Volts |
|---|---|---|---|
| Refrigerator | 800 | 1600 | 120 |
| Freezer | 600 | 1200 | 120 |
| HVAC System | 2000 | 4000 | 240 |
| Lights | 300 | – | 120 |
| Electronics | 400 | – | 120 |
| Microwave | 1000 | – | 120 |
| Washing Machine | 500 | 1500 | 120 |
| Electric Oven | 3000 | – | 240 |
| Dishwasher | 1200 | 1500 | 120 |
Example of Whole House Generator Size Calculator
Let’s walk through an example to illustrate the process:
- List your appliances and their power requirements:
- Refrigerator: 800 running watts, 1600 starting watts
- Freezer: 600 running watts, 1200 starting watts
- HVAC System: 2000 running watts, 4000 starting watts
- Lights: 300 running watts
- Electronics: 400 running watts
- Microwave: 1000 running watts
- Washing Machine: 500 running watts, 1500 starting watts
- Electric Oven: 3000 running watts
- Dishwasher: 1200 running watts, 1500 starting watts
- Calculate the total running power requirement:
- Total Running Power = 800 + 600 + 2000 + 300 + 400 + 1000 + 500 + 3000 + 1200 = 9500 watts
- Calculate the total starting power requirement:
- Total Starting Power = 1600 + 1200 + 4000 + 1500 + 1500 = 9800 watts
- Consider the higher of running and starting power requirements:
- Total Power Requirement = 9800 watts
- Add a safety margin:
- Recommended Generator Size = 9800 watts * 1.25 = 12250 watts
Most Common FAQs
A: Portable generators can power essential appliances but may not be sufficient for the entire house. It’s important to calculate your total power needs and ensure the generator can handle them.
A: Using a generator that’s too small can result in overloaded circuits, which can damage the generator and connected appliances. It’s crucial to size your generator correctly.
A: Regular maintenance is essential for reliable performance. It’s recommended to follow the manufacturer’s maintenance schedule, typically every 6 to 12 months.