1. What is a Generator Size Calculator?

Definition: This calculator estimates the appropriate generator size in kilowatts (kW) based on your total electrical load and a safety factor.

Purpose: It helps homeowners and contractors determine the right generator capacity for residential backup power needs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_{kW} \) — Generator size (kilowatts)
• \( \Sigma(P_{load}) \) — Sum of all electrical loads (watts)
• \( SF \) — Safety factor (typically 1.25-1.5)

Explanation: The total wattage is converted to kilowatts (divided by 1000) then multiplied by a safety factor to account for startup surges and future needs.

3. Importance of Proper Generator Sizing

Details: Correct sizing ensures your generator can handle all essential loads without being overloaded, while avoiding unnecessary costs for oversized units.

4. Using the Calculator

Tips:

• Add up the wattage of all appliances you want to power simultaneously
• Use a safety factor between 1.25 (for basic needs) to 1.5 (for heavy motor loads)
• Consider both running watts and startup surge watts for motors

5. Frequently Asked Questions (FAQ)

Q1: What's included in total load calculation?
A: Sum of all appliances you want to run simultaneously, including lights, refrigerator, AC, etc.

Q2: Why is a safety factor needed?
A: It accounts for motor startup surges (which can be 3-5x running watts) and future power needs.

Q3: What's a typical safety factor?
A: 1.25 for basic needs, 1.5 if you have many motor-driven appliances (AC, pumps, etc.).

Q4: How do I find appliance wattage?
A: Check nameplate ratings or use our Appliance Wattage Calculator.

Q5: Should I size for whole house or essential circuits?
A: Most homeowners size for essential circuits only (lights, fridge, furnace) to reduce cost.