AC Installation Cost in Seattle, Washington
Our 2026 estimate for new AC installation in Seattle, WA is $5,100 to $11,500. That puts Seattle 21% above the national average, mainly because of higher incomes and home values, which push labor rates up.
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Seattle Weather and HVAC Load
In a normal year, Seattle racks up 4,482 heating and 210 cooling degree days (NOAA 1991-2020 normals). Heating is the bigger job here. The AC still runs every summer, but it works far fewer hours than the furnace does. On average, Seattle gets 25 freezing nights and 2 days above 90°F per year. Snowfall averages about 4 inches.
| Heating degree days / year | 4,482 |
|---|---|
| Cooling degree days / year | 210 |
| Nights at or below 32°F | 25 |
| Days above 90°F | 2 |
| Average low / high | 45.7°F / 60.8°F |
Seattle Housing Stock
Census figures put the median build year in Seattle at 1974, so a typical house here has about 52 years on it. A lot of these homes are on their second or third system by now. The ductwork is usually original, and leaky joints are common. Seattle has roughly 156,000 owner-occupied homes, or 44.2% of households. Homes here have a median value of $912,100 and households a median income of $121,984. Those two numbers drive the labor adjustment in our estimate.
NOAA's Storm Events Database shows no hail or damaging-wind days for King County from 2020 through 2025, so storm damage to outdoor units is rare here.
When It Makes Sense
- It still runs on R-22 refrigerant
- The AC is 12 to 15 years old or more
- It has had more than one refrigerant leak
- Summer electric bills keep going up
What Moves the Price
- The pad, permit and refrigerant (R-410A or the newer R-454B)
- Electrical work such as a new disconnect, breaker or wiring
- Whether the coil and line set also need replacing
- SEER2 rating and whether the compressor is single-stage or variable-speed
- Tonnage, based on house size and local climate
We raised the national figures about 21% for Seattle using local income, home values and the equipment size this climate needs. Real bids can still come in outside the range, so collect three written quotes.
What the Quote Should Cover
- The new condenser, coil and, if needed, line set
- The electrical disconnect and wiring
- Refrigerant charge and a leak test
- Removing the old condenser and coil
- Startup, an airflow check and warranty registration
Washington Permits, Efficiency Rules and Rebates
Washington falls in the DOE's North region. New split central air conditioners must meet at least 13.4 SEER2, and heat pumps sold anywhere in the U.S. need 14.3 SEER2 and 7.5 HSPF2. Plan on a mechanical permit for most replacements in Seattle; the contractor normally pulls it. Before you sign, ask each bidder for their Washington license or registration number and proof of insurance. The federal 25C tax credit ended for equipment installed after December 31, 2025, so incentives now come mostly from utilities and state programs. Check your electric and gas utility's rebate page before you pick equipment.
Before You Hire
- Buy the condenser and coil as a matched set, or you may void the manufacturer warranty.
- Ask for a Manual J calculation. "Same size as the old one" isn't sizing.
- Fall and early spring installs often come with better pricing and shorter waits.
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AC Installation Questions from Seattle Homeowners
How much is new AC installation in Seattle?
Plan on $5,100 to $11,500, with most jobs near $8,600. Equipment efficiency, house size and the condition of the ducts and wiring decide where your quote falls.
When is the best time to schedule new AC installation in Seattle?
Between late spring and early fall. Seattle averages 25 freezing nights a year, and heating calls spike from November through February.
What size AC do I need?
It depends on square footage, insulation, windows and climate. The rough rule is a ton for every 450 to 650 sq ft, but only a Manual J calculation gives you a real number.
How long does a new AC last?
With yearly maintenance, 12 to 17 years. Salt air and extreme heat shorten that.
AC Installation Near Seattle
Sources: U.S. Census Bureau ACS 5-year estimates 2019-2023 and 2024 population estimates; NOAA NCEI U.S. Climate Normals 1991-2020, station Seattle Sand Point Wsfo; NOAA Storm Events Database 2020-2025, King County. Prices are our estimates, not contractor quotes. Updated 2026.