Whole House Generator Cost Calculator
Whole house generator cost depends on the size of the generator and on everything needed to connect it: the switchover gear, the fuel supply, a pad and permits often add as much as the unit. The calculator above prices the generator for the size you choose and adds the installation items one by one.
Generator size and installation items
Pick the size band, from small units that run a few circuits to 45 to 48 kW for a large home.
Extras cover automatic switchover gear, a gas line to the generator, a concrete pad, electrical and fuel line permits, a 500-gallon fuel tank above ground, a subpanel, a dedicated circuit and the first year of maintenance.
Start with the size
The generator is usually less than half the bill. A 20 to 24 kW unit costs $5,000 to $6,500, but installation labor adds $1,500 to $5,000, and a transfer switch, gas line, pad and permits come on top. Put together, whole house generator cost for that size lands around $8,350 to $15,350, close to 2026 planning ranges of $9,500 to $24,000 for a 22 to 25 kW installed system.
Manufacturer sizing guides put a 2,000 sq ft home at 18 to 22 kW and warns that a 3-ton central air conditioner can need up to 15 to 18 kW just to start. Unit prices by size:
| Generator size | Unit price |
|---|---|
| 7.5 to 10 kW | $2,000 to $3,500 |
| 14 to 18 kW | $4,000 to $5,500 |
| 20 to 24 kW | $5,000 to $6,500 |
| 26 to 32 kW | $6,500 to $15,000 |
| 36 to 38 kW | $14,000 to $16,000 |
| 45 to 48 kW | $16,200 to $21,000 |
A load manager can let a smaller standby generator cope with a large air conditioner.
Whole house generator cost installed: the line items
| Item | Cost |
|---|---|
| Installation labor | $1,500 to $5,000 |
| Automatic transfer switch, installed | $1,200 to $1,600 |
| Gas line to the generator | $400 to $1,500 or more |
| Concrete pad | $150 to $400 |
| Electrical and fuel line permits | $100 to $350 |
| Subpanel | $530 to $2,000 |
| Dedicated circuit | $500 to $1,000 |
The first five lines are on in the calculator; add a subpanel or circuit if your electrician says the panel needs it.
Compare the totals with care. Some older headline ranges, around $1,500 to $8,700 with an average near $5,100, sit well below current installed prices, which run $10,000 to $25,000 for 22 to 26 kW in 2026 sales data.
Natural gas or propane
Homes without a gas line need a propane tank: a 500-gallon above-ground tank costs $1,000 to $2,000 installed, or $1,500 to $2,500 buried, and leasing runs $150 to $180 a year.
Fuel is where the two split during a long outage. A 21 kW unit burning natural gas costs about $90 a day in fuel, while a 20 kW unit on propane runs about $220. Diesel models cost about $175 a day.
Keeping it running
A standby unit needs regular service: $80 to $300 a visit, or $200 to $600 a year for upkeep. With that care, it should last at least 20 years.
The cheaper route: a portable generator
For a smaller budget, a portable generator costs $500 to $2,000. It still needs a safe connection to the house. An installed interlock kit costs $400 to $900 and a 6-circuit manual transfer switch at $1,000 to $1,600. Even with the hookup, that stays well under the home generator cost of a permanent system.