May 4, 2026 · 5 min read
Natural Gas vs Propane: Which Fuel Should Power Your Generator?
Side-by-side comparison of runtime, cost, and reliability for the two most common standby generator fuels.
If you have natural gas at the house, the decision is usually made for you
Natural gas (NG) delivers an effectively unlimited runtime because it's piped in. You never refill anything. Most home standby generators are dual-fuel — they ship configured for NG and can be field-converted to propane in about 30 minutes.
Propane runs the same generator about 10% stronger
Propane has higher energy density than NG, so the same generator produces slightly more usable kW on propane (e.g., a 22 kW NG unit makes 24 kW on propane). That can be the difference between needing load management and not.
The catch: you need a tank. A 500-gallon underground tank gives a 22 kW generator roughly 5–7 days of typical-load runtime. A 1,000-gallon tank doubles that.
Reliability tiebreaker
In ice storms and major hurricanes, NG distribution can drop pressure or fail entirely if utility pumps lose power. Propane is on-site, full, and waiting. For high-risk regions (Gulf Coast, ice belt, wildfire country), a propane tank earns its keep.
Cost per kWh
Natural gas is roughly 30–50% cheaper per kWh than propane in most markets. But you're paying for resilience as much as fuel — and the gap closes fast if NG service is unreliable in your area.