by Generac
Generac Guardian 18kW
18 kW standby generator
Key specifications
- Rated output, propane
- 18 kW
- Rated output, natural gas
- 17 kW
- Fuel
- Dual fuel (NG / LP)
- Phase
- Single-phase
- MSRP (starting)
- $5,379
- Dimensions
- 48 x 25 x 29 in
- Weight
- 420 lb
- Engine displacement
- 816 cc
- Sound, running (23 ft)
- 65 dB
- Sound, exercise (23 ft)
- 55 dB
- Warranty
- 5 years
Unverifiable specs are omitted, not estimated. See sources below for what we can defend.
Fuel use
| Fuel | Half load | Full load |
|---|---|---|
| Propane | 1.7 gal/hr | 3.02 gal/hr |
| Natural gas | 169 ft³/hr | 247 ft³/hr |
On propane, a 500-gallon tank filled to 80% holds about 400 gallons. That runs the Generac Guardian 18kW for about 235 hours (9.8 days) nonstop at half load, or about 132 hours (5.5 days) at full load. See how much propane a generator uses for other tank sizes.
On natural gas, the gas line and meter have to deliver the full-load figure, 247 ft³/hr, even if the generator rarely runs that hard. Installers size the pipe to it.
Sources
Every spec above traces back to one of these citations.
- Generac product page — Standby Generator 18kW WiFi Enabled Guardian Series (G0072260) · checked July 2026
- Generac spec sheet: 10/14/18 kW Guardian Series · checked September 2026
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