Generator Installation Cost Calculator
* Includes generator unit and professional installation. Final costs vary by brand, site preparation, and local electrical codes.
Disclaimer: Estimates are for budgeting purposes only. Actual costs vary by location, contractor, material availability, and project complexity. Always get professional quotes for exact pricing.
Generator Cost by Size
| Generator Size | Unit Cost | Installed Cost* |
|---|---|---|
| Portable (3–7.5 kW) | $500 – $2,000 | $500 – $2,000 |
| 7–10 kW Standby | $3,000 – $5,000 | $4,300 – $8,800 |
| 12–16 kW Standby | $4,000 – $7,000 | $5,300 – $10,800 |
| 20–24 kW Standby | $5,000 – $9,000 | $6,300 – $12,800 |
| 30 kW+ Standby | $8,000 – $15,000 | $9,300 – $18,800 |
* Installed cost includes transfer switch, concrete pad, and gas line. Portable generators do not require professional installation.
How We Calculate
Our generator installation cost calculator estimates total project costs based on generator size and add-on options. Pricing includes the generator unit and professional installation.
How the math works: Generator cost = base unit cost by kW size. Add-ons: transfer switch ($500–$1,500), concrete pad ($300–$800), gas line ($500–$1,500). Total = generator + selected add-ons.
Generator Sizes
Portable ($500–$2,000): Manual start, 3–7.5 kW output. Powers essential appliances via extension cords or manual transfer switch. Not a whole-home solution. Best for occasional use and short outages. Gasoline-powered, requires manual refueling.
7–10 kW Standby ($3,000–$5,000): Covers essential circuits: refrigerator, sump pump, furnace blower, lights, and a few outlets. Most affordable standby option. Automatic start with transfer switch. Good for areas with occasional outages. Does not power central AC.
12–16 kW Standby ($4,000–$7,000): Powers most home circuits including small AC unit (up to 3 ton). Suitable for 2,000–3,000 sq ft homes. Can run well pump, washer, dryer, and kitchen appliances simultaneously. Most popular residential size range.
20–24 kW Standby ($5,000–$9,000): True whole-home coverage for most homes. Powers central AC (up to 5 ton), all outlets, and major appliances. Handles simultaneous high-demand loads. Suitable for 3,000–5,000 sq ft homes. Brands like Generac Guardian 22 kW and Kohler 20RESCL fall in this range.
30 kW+ Standby ($8,000–$15,000): Large home and estate coverage. Multiple AC zones, electric heating, pool equipment, and workshop loads. Required for homes over 5,000 sq ft or with 400-amp electrical service. May require 3-phase power in commercial applications.
Installation Components
Automatic transfer switch ($500–$1,500): Required by code. Detects outage, starts generator, transfers load within 10–30 seconds. 100–200 amp capacity. Service-entrance rated for whole-home or load-management type for partial coverage. Installed at main electrical panel.
Concrete pad ($300–$800): Generator mounting surface, 3–4 inches thick, 3x4 feet minimum. Must be level and at least 5 feet from windows, doors, and fresh-air intakes. Some manufacturers offer composite pads ($200–$400) as alternative.
Gas line ($500–$1,500): Natural gas or propane supply line from meter/tank to generator. Typically 1-inch or 1.25-inch black pipe or CSST flexible line. Length varies (20–50 feet typical). Requires plumbing permit and pressure test. Propane installations may need a larger tank ($500–$2,000 for 250–500 gallon tank).
Data Sources
Pricing from Generac, Kohler, and Briggs & Stratton dealer networks, HomeAdvisor, and licensed electrical contractors. Code requirements per NEC Article 702 and local building departments. We review and update costs regularly.
Last updated: 2026-02-11
Frequently Asked Questions
How much does a whole-house generator cost to install? +
A whole-house standby generator costs $5,000–$15,000 installed. A 20 kW generator (covers most homes) runs $5,000–$9,000 for the unit plus $1,300–$3,800 for installation extras: automatic transfer switch ($500–$1,500), concrete pad ($300–$800), and gas line ($500–$1,500). Portable generators cost $500–$2,000 but don't power the whole home. Popular brands include Generac, Kohler, and Briggs & Stratton.
What size generator do I need for my house? +
Generator size depends on what you want to power. Essential circuits only (fridge, sump pump, lights, furnace) need 7–10 kW ($3,000–$5,000). Most home circuits (including AC) need 12–16 kW ($4,000–$7,000). Whole-home coverage with central AC and electric heat needs 20–24 kW ($5,000–$9,000). Large homes with multiple AC units need 30 kW+ ($8,000–$15,000). An electrician can perform a load calculation to determine exact sizing.
Natural gas vs propane generator — which is better? +
Natural gas generators are best if you have an existing gas line — no fuel storage needed and unlimited supply during outages. Propane generators are ideal for rural areas without gas service — propane stores indefinitely and burns cleaner. Dual-fuel generators ($200–$500 more) offer flexibility to use either fuel. Natural gas delivers slightly less power per BTU than propane. Both require professional fuel line installation ($500–$1,500).
Do I need a transfer switch for a generator? +
Yes, a transfer switch ($500–$1,500) is required by electrical code (NEC Article 702) for any generator permanently connected to your home. Automatic transfer switches (ATS) detect power outages and start the generator within 10–30 seconds. Manual transfer switches ($300–$800) require you to flip the switch. ATS is standard for standby generators. Without a transfer switch, backfeeding can electrocute utility workers and damage equipment.
How long does generator installation take? +
Standby generator installation takes 1–2 days. Day 1: pour concrete pad, run gas line, install transfer switch. Day 2: set generator on pad, connect gas and electrical, test and commission. Electrical permit and inspection add 1–2 weeks to the timeline. Gas line installation (if needed) may require a separate plumbing permit. Most installers complete the physical work in 8–12 hours total.
What are the ongoing costs of a standby generator? +
Annual standby generator maintenance costs $200–$500. Includes oil change ($50–$100), air filter ($20–$40), spark plugs ($30–$60), and battery check ($0–$50). Professional annual service contract runs $200–$400. Fuel cost during an outage: natural gas ($30–$50/day for 20 kW), propane ($40–$70/day). Generators run weekly self-tests (5–10 minutes). Expected lifespan is 10,000–30,000 hours or 25–30 years with maintenance.
Can I install a generator myself? +
Portable generators need no installation, but standby generators require licensed electrician and plumber for code-compliant installation. Electrical permit is required for transfer switch installation. Gas line work requires licensed plumber or gas fitter. Improper installation risks carbon monoxide poisoning, electrical fires, and voided warranty. DIY savings are minimal compared to safety risks. Most municipalities require inspections before operation.
How much does a Generac generator cost? +
Generac standby generators cost $3,000–$15,000+ depending on size. The Generac Guardian 10 kW runs $3,000–$4,000 (unit only). The popular Guardian 22 kW costs $5,000–$6,500. The Guardian 24 kW with PWRview costs $6,000–$7,500. Add $1,300–$3,800 for installation (transfer switch, pad, gas line). Generac holds about 75% of the residential standby generator market. Kohler and Briggs & Stratton are comparable alternatives at similar price points.
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