1. What is a Generator Size Calculator?

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

Purpose: It helps homeowners and professionals determine the appropriate generator capacity for backup power needs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P_{kW} \) — Generator size (kilowatts)
• \( \Sigma P_{load} \) — Total electrical load (watts)
• \( SF \) — Safety factor (typically 1.2 for residential use)

Explanation: The total load in watts 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 generator sizing ensures reliable power during outages, prevents overload damage, and improves fuel efficiency.

4. Using the Calculator

Tips: Enter the total wattage of all appliances you want to power simultaneously and a safety factor (default 1.2). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why do we need a safety factor?
A: The safety factor accounts for motor startup surges (which can be 3-5x running watts) and potential future power needs.

Q2: How do I find my total load?
A: Add up the wattage of all appliances you want to run simultaneously. Check appliance labels or manuals for wattage information.

Q3: When would I change the safety factor?
A: Use 1.5 for heavy motor loads (like AC units), 1.2-1.3 for typical residential loads, and 1.1 for lighting-only loads.

Q4: Should I size for running watts or starting watts?
A: This calculator automatically accounts for starting watts through the safety factor. Enter the running watts only.

Q5: Does this include whole-house needs?
A: This calculates for the loads you specify. For whole-house sizing, include all essential circuits and appliances.