How to Choose the Right Generator Size for Your Home

TL;DR: Choosing the right generator size depends on your total wattage needs, fuel type, and whether you want to power your whole property or just essential circuits. A licensed generator company can assess your load requirements and recommend the right unit—preventing costly over- or under-sizing mistakes.

Losing power for a few hours is an inconvenience. Losing it for days—during a winter storm, a heat wave, or a major grid failure—can be dangerous. For homeowners and businesses across South Jersey, a properly sized backup generator is one of the smartest investments you can make.

But "properly sized" is the key phrase. Too small, and your generator won't handle the load. Too large, and you've overspent on capacity you'll never use. Getting it right requires understanding your energy needs, your property type, and a few key technical factors.

This guide walks you through everything you need to know—so when you're ready to move forward, you can do it with confidence.

Key Takeaways

• Calculate your total wattage needs before choosing a generator—starting wattage for appliances like AC units and refrigerators is often 2–3x their running wattage.

• Whole-home standby generators (22–48kW) suit most South Jersey households, while portable units work best for selective, short-term backup power.

• Working with a qualified generator company in South Jersey ensures your system is correctly sized, safely installed, and code-compliant from day one.

• 
  

What Does "Generator Size" Actually Mean?

Generator size refers to power output, measured in watts (W) or kilowatts (kW). A generator's rated—or running—wattage is the continuous power it can produce. Its surge—or starting—wattage is the higher burst of power it can briefly supply to start motor-driven appliances like air conditioners, refrigerators, and sump pumps.

This distinction matters. A refrigerator might only need 150 watts to run, but it can require 600 watts to start. If your generator can't handle that surge, it will trip or shut down.

How to Calculate What Your Home or Business Actually Needs

The starting point for any generator sizing decision is a load calculation—a tally of everything you want to power.

Step 1: List Your Essential Appliances

Start by identifying what you can't go without during an outage. For most South Jersey homeowners, this includes:

• Central air conditioning or heating system

• Refrigerator and freezer

• Sump pump (critical during storms)

• Lights and outlets

• Medical equipment, if applicable

• 
  

Businesses may also need to factor in security systems, point-of-sale equipment, servers, and commercial HVAC units.

Step 2: Find the Running and Starting Wattage

Check the label or manual for each appliance. If a device uses amps rather than watts, multiply amps by voltage (typically 120V or 240V) to get watts. For motor-driven appliances, assume a starting wattage 2–3 times higher than the running wattage.

Step 3: Add It All Up

Total your running watts, then identify the single appliance with the highest starting wattage and add that figure on top. The result is the minimum generator capacity you need. Most generator professionals recommend adding a 20–25% buffer to that number for safety and future load growth.

Portable vs. Standby Generators: Which Is Right for You?

Once you know your load requirements, you'll face a fundamental choice: portable or standby.

Portable generators are lower cost upfront and can be stored when not in use. They run on gasoline and must be manually started and connected. They're suited for temporary, selective power—running a few appliances during a short outage. However, they require outdoor operation, refueling, and extension cords, which adds complexity and safety considerations.

Standby generators are permanently installed, connected directly to your electrical panel, and powered by natural gas or propane. They start automatically within seconds of a power outage—no manual intervention required. For South Jersey homeowners who experience frequent outages due to coastal storms or summer heat events, standby systems offer a level of reliability that portable units simply can't match.

For most residential and commercial applications, a whole-home standby generator in the 22–48kW range is the go-to recommendation from South Jersey generator installation professionals.

What Size Generator Does a South Jersey Home Typically Need?

There's no universal answer, but here are general benchmarks:

• Small home (under 1,500 sq ft), essential circuits only: 7–12kW

• Mid-size home (1,500–2,500 sq ft), whole-home backup: 14–20kW

• Larger home or home with EV charger/pool pump: 22–36kW

• Small business or commercial property: 30kW and above, depending on load

  
  

South Jersey's climate plays a role here. Humid summers drive heavy air conditioning use, which spikes peak demand. Homes with multi-zone HVAC systems, electric water heaters, or high-draw appliances should size up accordingly.

Common Sizing Mistakes to Avoid

Even well-intentioned buyers make these errors:

Underestimating starting wattage. Motor-driven appliances draw far more power at startup than they do while running. Ignoring this leads to generator overload and potential damage.

Forgetting the sump pump. In South Jersey, flooding during nor'easters and tropical systems is a real risk. A sump pump failure during a storm can cause thousands of dollars in water damage—make sure it's in your load calculation.

Buying based on price alone. A generator that's 20% cheaper but 30% underpowered isn't a bargain. Work with a licensed generator company in South Jersey to match capacity to actual need.

Skipping a transfer switch. A transfer switch safely isolates your generator from the utility grid, protecting both your equipment and utility workers. It's not optional—it's required by code in New Jersey.

Why Professional Installation Makes the Difference

Sizing a generator is one part of the equation. Installing it correctly is another. South Jersey generator installation involves more than connecting wires—it includes:

• Determining proper placement (clearance from windows, doors, and gas meters)

• Sizing the transfer switch or automatic transfer switch (ATS)

• Running gas lines to the correct specification

• Permitting and inspections required by New Jersey state and local codes

• Load bank testing to confirm performance before the first outage

  
  

Krise Services handles all of this for residential and commercial clients across South Jersey. From the initial site assessment to the final inspection, every installation is designed to meet code, perform under pressure, and last for years.

Your Next Step Toward Reliable Power

Choosing the right generator size doesn't need to be complicated—but it does need to be done right. Start with an honest assessment of your energy needs, factor in South Jersey's weather patterns, and work with a qualified professional who can match the right unit to your property.

Krise Services offers no-pressure consultations for homeowners and business owners throughout the region. Whether you're looking at your first standby generator or replacing an aging unit, the team will walk you through your options and help you make a confident, informed decision.

Ready to get started? Contact Krise Services today to schedule your free generator sizing consultation.

Frequently Asked Questions

What size generator do I need for a 2,000 sq ft home in South Jersey?Most 2,000 sq ft homes with central air conditioning, a refrigerator, sump pump, and standard lighting will need a 16–22kW standby generator for whole-home coverage. A licensed installer can perform a full load calculation to confirm the right size for your specific appliances and usage patterns.

How much does generator installation cost in South Jersey?Costs vary based on generator size, fuel type, transfer switch requirements, and site conditions. Whole-home standby systems typically range from $5,000 to $15,000 installed. Krise Services provides detailed quotes after an on-site assessment.

What fuel type is best for a South Jersey home generator?Natural gas is the most convenient option for homes already connected to a gas line—no fuel storage required. Propane is a strong alternative for properties without gas service. Both fuel types are commonly used in South Jersey generator installation projects.

Do I need a permit to install a generator in New Jersey?Yes. New Jersey requires permits for standby generator installations, including electrical and gas permits. A licensed generator company in South Jersey like Krise Services manages the permitting process on your behalf.

How long does a standby generator installation take?Most residential installations are completed in one to two days, assuming permits are already in place. More complex commercial installations may take longer depending on load requirements and site conditions.