GCGenerator Cost Calculator

18 kW standby power

18 kW Whole-House Generator Cost: Equipment and Installation

Price an 18 kW standby-generator scenario with the transfer, fuel, electrical, pad and permit scope left visible.

Direct answer

Current equipment evidence places 14–18 kW standby generators around $4,000–$5,500 unit only, while Generac lists its current 18 kW cellular model 7259 from $5,709 MSRP. Neither is an installed total: the calculator adds the selected site, transfer switch, fuel line, pad and permit work without claiming 18 kW is the correct size for the home.

What changes the result?

A useful calculation starts with the physical scope and the written commercial terms. These are the factors to make explicit:

  • Measured running and starting loads
  • Natural-gas or propane output
  • Transfer-switch and load-management design
  • Fuel pressure, pipe or tank capacity
  • Placement, electrical work, permits and commissioning

Use one scope for every quote

Give each business the same information and ask it to resolve the same boundaries. That makes the totals more comparable and exposes work left as an allowance or exclusion.

  1. Obtain a load calculation
  2. Confirm output on the selected fuel
  3. Separate generator and installation scope
  4. Require startup, testing and warranty registration

Separate the 18 kW unit from the installed system

Generac currently lists the 18 kW cellular model 7259 from $5,709 generator-only MSRP. Angi's wider 14–18 kW equipment observation is $4,000–$5,500, illustrating that model, channel and package contents matter.

The prefilled calculator uses a typical site, automatic transfer switch, 20 feet of new fuel-line allowance, pad and permits. Remove an item only when the written equipment package or contractor proposal already includes it.

18 kW on propane may not mean 18 kW on natural gas

The current model 7259 specification lists 18 kW maximum continuous capacity on liquid propane and 17 kW on natural gas. Product output, circuit arrangement and fuel conditions therefore belong in the sizing decision rather than relying on the marketing name alone.

Ask the installer to document the loads, starting requirements, transfer strategy and any load-shedding priorities. Capacity is an engineering and lifestyle decision; this page prices an entered scenario only.

Fuel and transfer equipment can change the project

The manufacturer specification lists fuel-pressure and full-load consumption information for the exact model, but that does not certify the property's meter, regulator, tank or pipe. A qualified installer must verify available pressure and volume across expected loads.

Confirm the exact automatic transfer switch, service rating, protected circuits or whole-service arrangement, conductors, trenching, grounding, clearances, pad, permits, startup test and owner handover. Compare identical scope before comparing totals.

Questions people ask

How much does an 18 kW standby generator cost?

Current evidence is roughly $4,000–$5,500 for equipment in the 14–18 kW class, while Generac lists model 7259 from $5,709 MSRP. Installation and system components are additional unless explicitly bundled.

Will an 18 kW generator run my whole house?

It depends on measured running and starting loads, fuel output, transfer design and load management. Have a qualified installer perform the calculation.

Is 18 kW the same on natural gas and propane?

Not for every product. Generac currently rates model 7259 at 18 kW on propane and 17 kW on natural gas.

Does the generator price include a transfer switch?

Not necessarily. Confirm the exact package. The calculator exposes a separate switch allowance so it can be turned off when genuinely included.

Method and sources

The model is a planning tool, not a quotation. These are the published sources used for this page; read the full assumptions before relying on a range. Source review: 17 September 2026.

Review full methodology