Natural Gas:Runs continuously as long as gas supply is available

Propane:A 20 kW generator uses about 2–3 gallons per hourA 500-gallon tank typically lasts 7–10 days under moderate load

Diesel:Uses about 0.5–1 gallon per hour depending on size and load

Run time depends heavily on how much of the home you are powering. Whole-home backup uses significantly more fuel than essentials-only setups.

Yes — but it depends on how the system is designed.

Whole-home systems:

Power everything Require larger generators (20–30+ kW)

Load-managed systems:

Prioritize circuits Temporarily shed large loads like AC Allow for smaller, more efficient generators

What this means:

• If you want your home to run exactly as it normally does during an outage, you’ll need a larger, whole-home system

• If you’re comfortable prioritizing essential systems and allowing high-demand items (like AC or electric appliances) to cycle on and off, you can use a smaller generator

• The difference in size can be significant — often 10 kW or more, which impacts both upfront cost and fuel usage

• Most homeowners choose a middle ground: keeping core systems always on while managing larger loads automatically

Whole-home systems:

Power everything in your home at the same time.

Typical setup includes:

• HVAC (air conditioning and heating)

• Kitchen appliances (refrigerator, oven, microwave)

• Laundry (washer and dryer)

• Lights, outlets, and electronics

• Well pump or sump pump (if applicable)

Example:A 3,000 sq ft home with:

• 2 AC units

• Electric range and dryer

• Finished basement

Would typically require a 22–30 kW generator to run everything without interruption.

Load-managed systems:

Prioritize essential circuits and rotate larger systems on and off as needed.

Typical setup includes:

• Always on:

  • Refrigerator

  • Lights

  • Internet and outlets

  • Furnace fan or boiler

• Cycled or limited:

  • Air conditioning (runs one unit at a time)

  • Electric range or dryer (may be temporarily shut off)

Example:The same 3,000 sq ft home:

• Runs lights, fridge, and core systems continuously

• Allows only one AC unit at a time

• Temporarily pauses large appliances during peak demand

This setup could use a 14–20 kW generator instead of 22–30 kW

How do you decide which one you need?

It comes down to three things:

• Comfort expectations:Do you want everything to run normally, or just the essentials?

• Budget:Whole-home systems cost more upfront and use more fuel

• Power demand:Larger homes with multiple AC units or electric appliances often benefit from load management

⚡️ Most homeowners land somewhere in the middle — wanting key systems always on, with larger loads managed intelligently.

Whole-home systems:

• Power everything

• Require larger generators (20–30+ kW)

Load-managed systems:

• Prioritize circuits

• Temporarily shed large loads like AC

• Allow for smaller, more efficient generators

Start with what you want to power, not square footage.

Step 1: Choose your coverage level

Essentials only (most common):

• Refrigerator: ~600–800W (startup up to 2,000W)

• Lights: ~300–800W total

• Sump pump: ~800–1,500W (startup higher)

• Internet/TV: ~200–400W

Typical total: 5–10 kW generator

Partial home (adds comfort systems):

• Everything above +

• Furnace fan: ~600–1,200W

• Well pump: ~1,000–2,000W

Typical total: 10–18 kW generator

Whole home (including HVAC):

• Everything above +

• Central AC: ~3,000–5,000W (startup much higher)

Typical total: 18–30+ kW generator

Step 2: Understand startup vs running load

Big appliances (AC, pumps) require 2–3x power at startup. This is why most systems are undersized if guessed.

Step 3: Quick baseline rule (for your calculator)

• Small home (under 2,000 sq ft): 10–14 kW

• Mid-size (2,000–3,500 sq ft): 14–22 kW

• Large home (3,500+ sq ft): 22–30+ kW

⚡️ But always adjust based on what you actually want to power

Sizing based on square footage alone.

Square footage gives a rough starting point, but it doesn’t account for how your home actually uses power.

What actually matters:

What needs to run — make a list of what you want powered during an outage:

• Essentials: refrigerator, lights, internet, sump pump

• Comfort systems: furnace, well pump

• Full-home: air conditioning, electric range, dryer

Two homes with the same square footage can need completely different generator sizes depending on this list.

Startup loads from major systems — some equipment requires significantly more power to start than to run:

• Air conditioners

• Well pumps

• Sump pumps

These can draw 2–3x their normal wattage at startup, which is why generators sized only on running load often fail under real conditions.

Fuel type and availability

Your fuel source affects both runtime and system size:

• Natural gas: continuous supply, ideal for long outages

• Propane: limited by tank size (larger systems use more fuel)

• Diesel: efficient but requires on-site storage and maintenance

⚡️ Larger generators provide more power but also consume more fuel per hour.

What this means:

• A 2,500 sq ft home running only essentials might need a 10–14 kW generator

• The same home running two AC units and electric appliances could need 20–26+ kW

• Oversizing increases upfront cost and fuel usage

• Undersizing can cause system overload or failure when you need it most

⚡️ The right system isn’t based on home size — it’s based on how your home actually uses power.

Generator maintenance is what ensures your system works when it’s needed — not just when it’s tested.

What maintenance actually includes:

• Oil and filter changes

• Battery inspection and replacement if needed

• Fuel system checks (quality, leaks, and stability)

• Air filter replacement

• Inspection of belts, hoses, and connections

• System diagnostics and control panel checks

• Load testing to confirm performance under real demand

⚡️ These aren’t cosmetic — they directly impact whether the generator will start, carry load, and run consistently during an outage.

Why maintenance matters:

Most generator failures are not due to major mechanical issues — they’re caused by:

• Dead or weak batteries

• Degraded fuel

• Lack of load testing

• Small issues that were never caught early

⚡️ Generators often “pass” basic tests but fail when they’re actually needed because they’ve never been tested under real conditions.

When maintenance is typically needed:

• Once per year (standard for most homes)

• After extended use during a major outage

• Every 100–200 runtime hours (whichever comes first)

⚡️ Even if your generator hasn’t been used much, time-based maintenance is still important because components degrade over time.

When you should call for service:

• The generator doesn’t start automatically during a test

• You see warning lights or error messages

• It runs rough, shuts down unexpectedly, or struggles under load

• It hasn’t been serviced in over a year

• You’ve had a long outage and want to confirm it’s still in good condition

What this means:

A generator isn’t something you check once and forget.

It’s a system that sits idle most of the time — which is exactly why maintenance matters. The goal isn’t just to keep it running, but to make sure it performs under real conditions when you actually need it.