Generator kW Size Calculator

Generator Size Formula:

\[ P_{kW} = \frac{\sum P_{load}}{1000} \times SF \]

Generator Size (kW):

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1. What is a Generator kW Size Calculator?

Definition: This calculator determines the appropriate generator size in kilowatts based on the total electrical load and a safety factor.

Purpose: It helps homeowners, businesses, and electricians select the right generator capacity for backup power needs.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ P_{kW} = \frac{\sum P_{load}}{1000} \times SF \]

Where:

\( P_{kW} \) — Generator size in kilowatts
\( \sum P_{load} \) — Total connected load in watts
\( SF \) — Safety factor (typically 1.2-1.5)

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

3. Importance of Proper Generator Sizing

Details: Correct sizing ensures reliable power during outages, prevents overload conditions, and maximizes fuel efficiency.

4. Using the Calculator

Tips: Enter the total connected load in watts and safety factor (default 1.25). Load must be > 0 and safety factor ≥ 1.

5. Frequently Asked Questions (FAQ)

Q1: Why is a safety factor needed?
A: It accounts for motor startup currents (which can be 3-5x running current) and potential future load additions.

Q2: What's a typical safety factor?
A: Residential: 1.2-1.3, Commercial: 1.3-1.5, Industrial: 1.5+ depending on motor loads.

Q3: How do I find my total load?
A: Sum the wattage of all devices to be powered simultaneously, or use our Load Calculator tool.

Q4: Should I size for continuous or peak load?
A: The safety factor handles peak demands, so enter your continuous load total.

Q5: What about three-phase systems?
A: For three-phase, use our Three-Phase Generator Calculator for precise sizing.