Guide / Exhaust fan quotes, United States

Bathroom exhaust fan install cost: what the quote should show

Toshikatsu Oga / October 16, 2026

The five kinds of lines
Step 1: what the code asks the fan to do
Step 2: the fan, by model number
Step 3: the duct and the cap
Step 4: labor hours times a wage
The lines with no public benchmark
Warning signs in the wording, not the numbers
What to ask the contractor, in one message
Questions
Sources

A bath fan quote is five kinds of lines, and the duct decides whether the fan does its job. The fan, the duct and roof or wall cap, the electrical work, the ceiling patch and the permit. Seattle's published adoption of the 2021 International Residential Code lists 50 cfm intermittent or 20 cfm continuous for a bathroom. It also says air "shall not be exhausted into an attic, soffit, ridge vent or crawl space" (2021 Seattle Residential Code, Chapter 15). The fan's rated airflow can be checked by model number in the ENERGY STAR or HVI listings (ENERGY STAR, HVI). The labor can be set against BLS wages: $30.38 median and $52.17 at the 90th percentile per hour for electricians nationally (BLS OEWS, May 2025). The duct, cap and patch lines have no public price benchmark, so the check there is what they contain. The permit fee is on your city's fee schedule.

The five kinds of lines

Kind	Typical wording	What you can check
Fan unit	Exhaust fan, 80 cfm, 1.0 sone, with or without light	Model number against the ENERGY STAR or HVI listing
Duct and cap	4 in. flex duct, roof jack, wall cap, damper	Diameter, type and length against the code's duct length table
Electrical	Wiring, switch, timer, humidity sensor	Hours times BLS wages; which control, by model
Ceiling patch	Cut opening, patch, texture, paint	No public price; ask what size opening and whether paint is included
Permit	Electrical or mechanical permit	Your city's fee schedule and the permit number

A replacement in the same opening, on a working duct and switch, touches fewer lines than a new fan in a bathroom that never had one. Ask the contractor which of the two your quote prices.

Step 1: what the code asks the fan to do

The International Code Council publishes the 2021 International Residential Code (IRC) online. Free viewing is limited, and printing and other features need a paid Premium subscription (ICC). So the text below is quoted from the City of Seattle's published 2021 Seattle Residential Code, Chapter 15, which adopts the 2021 IRC with Washington and Seattle amendments (Seattle). Your city may differ; ask its building department.

Airflow. Seattle's Table M1505.4.4.1 lists 50 cfm intermittent and 20 cfm continuous for bathrooms and toilet rooms. That table carries a Washington amendment tag. Larimer County, Colorado, which uses the 2024 IRC, states the same 50 cfm intermittent and 20 cfm continuous for bathrooms (Larimer County). Intermittent means the fan runs when someone switches it on; continuous means it runs all the time at the lower rate.
Outdoors, not the attic. Section M1501.1: "Air shall not be exhausted into an attic, soffit, ridge vent or crawl space." Section M1505.2: bathroom exhaust air "shall not be recirculated within a residence" and "shall be exhausted directly to the outdoors" (Seattle, Chapter 15).
Duct length. Section M1504.2 limits exhaust duct length to Table M1504.2. The limit does not apply where the duct follows the manufacturer's design criteria, or where the installer or an approved third party verifies the installed airflow with a flow hood, flow grid or other airflow measuring device (Seattle, M1504.2). Step 3 shows why this matters.

A fan that blows into the attic space, or a duct that ends just short of the roof, does not meet that text. Ask where the duct ends, in writing.

Step 2: the fan, by model number

A line that says "exhaust fan" with no model cannot be checked. Ask for the brand and model number, then look it up. ENERGY STAR sets these limits for bathroom and utility room fans (ENERGY STAR Key Product Criteria):

Airflow range	Minimum efficacy	Maximum sound
10 to 89 cfm	2.8 cfm per watt	2.0 sones
90 to 200 cfm	3.5 cfm per watt	2.0 sones
201 to 500 cfm (max speed)	4.0 cfm per watt	3.0 sones

The same page says certified models "must deliver a tested airflow (CFM) at 0.25 in. w.g. static pressure" that is at least 70% of the airflow at 0.1 in. w.g., and that each model must be certified by an EPA-recognized certification body. So a fan rated 80 cfm at 0.1 in. w.g. must still move at least 80 x 0.70 = 56 cfm at 0.25 in. w.g. in the test. Real ducts add resistance. Seattle's amended table says the bathroom rate is measured at a static pressure of 0.25 inch water column, so that is the figure to compare with 50 cfm.An ENERGY STAR record prints it as "Bathroom and Utility Room Airflow at 0.25 in. w.g.", next to the sones, the efficacy and the duct size the fan was built for (example record).

Not every fan is ENERGY STAR certified. The Home Ventilating Institute keeps a directory that "includes more than 2,800 residential ventilation products", all "tested according to HVI procedures" (HVI directory). HVI says products bearing its label "have been tested and certified to ensure they meet the stated ratings" and that lower sones mean a quieter fan (HVI). If the model is in neither listing, ask where its airflow figure comes from.

Step 3: the duct and the cap

The duct is where a good fan loses its airflow. Table M1504.2 gives the maximum duct length for each fan rating at 0.25 inch water column. A few cells, as printed in Seattle's code, for fans rated 50 or 80 cfm at 0.25 inch water column (Seattle, Table M1504.2):

Duct diameter	Flex, 50 cfm	Flex, 80 cfm	Smooth wall, 50 cfm	Smooth wall, 80 cfm
3 in.	Not allowed	Not allowed	5 ft	Not allowed
4 in.	56 ft	4 ft	114 ft	31 ft
5 in.	No limit	81 ft	No limit	152 ft
6 in.	No limit	No limit	No limit	No limit

The table assumes no elbows; "Fifteen feet of allowable duct length shall be deducted for each elbow installed in the duct run" (footnote c). A worked case: a fan rated 80 cfm at 0.25 inch, on 12 feet of 4-inch flex duct with one elbow. The table allows 4 feet with no elbows, and one elbow deducts 15 feet, so no length of 4-inch flex with an elbow fits. On 4-inch smooth duct the limit is 31 - 15 = 16 feet, so 12 feet fits. On 5-inch flex it is 81 - 15 = 66 feet. The exception still applies: a run that follows the fan maker's design criteria, or whose airflow is measured after installation, is not held to the table.

The Department of Energy's Building America Solution Center adds practical points. "Choose a smooth-surfaced duct such as galvanized sheet metal or PVC that is the size specified by the manufacturer." Keep "the first three feet of duct extending from the fan exhaust port" straight. Insulate the duct to minimize condensation. Use a wall cap with "a damper that closes when the fan is not exhausting" (BASC). Ask the quote to name the duct type, diameter, length, number of elbows, and the cap.

Step 4: labor hours times a wage

Find the people and the hours behind the labor, or ask for them. The BLS May 2025 national wage for electricians (SOC 47-2111) is $30.38 median and $52.17 at the 90th percentile per hour. For drywall and ceiling tile installers (SOC 47-2081) it is $28.33 median and $49.04 at the 90th percentile (BLS OEWS).

Trade	Hours	At the median	At the 90th percentile
Electrician	8 (one 8-hour day)	8 x $30.38 = $243.04	8 x $52.17 = $417.36
Drywall patch	4 (half of one 8-hour day)	4 x $28.33 = $113.32	4 x $49.04 = $196.16
Total	12	$356.36	$613.52

Illustrative hours, written for teaching; your job may take more or less. These are plain wages, not billing rates: insurance, payroll taxes, the truck, tools, travel, overhead and profit sit on top, and no public rule fixes how much. Use the figure to ask what the labor line covers, not to call it high. Our overhead and profit guide covers the markup.

The lines with no public benchmark

We found no public price source for a bath fan, a roof jack, a length of duct, a ceiling patch or a timer switch at the price a contractor charges. Retail shelf prices exist, but they are not the contractor's cost or a fair markup. So for these lines, ask what they contain:

Fan: brand and model number, rated cfm at 0.25 in. w.g., and sones.
Duct and cap: flex or smooth, diameter, feet, elbows, roof or wall, and whether the cap has a damper.
Electrical: reuse of the existing circuit and switch, or new wiring; which control (plain switch, timer, humidity sensor), by model.
Ceiling patch: whether the new housing fits the old opening, and whether texture and paint are included.
Permit: whether one is required where you live, its fee from the city's schedule, and the permit number once pulled.

Warning signs in the wording, not the numbers

"Vent into attic" or "vent to soffit." The code text quoted above says air shall not be exhausted into an attic, soffit, ridge vent or crawl space (M1501.1).
"Exhaust fan, installed" with no model. Without the model you cannot check the rated airflow or sones (ENERGY STAR).
"Connect to existing duct" with no size or length. A fan rated 80 cfm at 0.25 inch, on 4-inch flex, is limited to 4 feet in the code's table (Table M1504.2).
"Homeowner to obtain permit." The FTC lists "Scammers ask you to get any required building permits" among its warning signs (FTC).
"This price is only good today." A sale of $25 or more made at your home can be cancelled "at any time prior to midnight of the third business day" under the FTC Cooling-Off Rule, which lists exceptions, including a repair or maintenance visit you asked for yourself (16 CFR Part 429). See what to do when the price is only good today.

What to ask the contractor, in one message

The fan's brand and model number, its rated cfm at 0.25 in. w.g., and its sones; and whether it is listed by ENERGY STAR or HVI.
Whether the fan will run intermittently (50 cfm) or continuously (20 cfm), and the control that runs it, by model.
Where the duct ends: roof or wall cap, with a damper, outdoors.
The duct type, diameter, length and number of elbows, and whether the existing duct is reused.
The people and hours behind the labor, and whether new wiring is included.
The ceiling patch scope, and whether a permit is required and included, with the permit number once pulled.

If you would rather not do it line by line, upload the quote and we do it, with every source and formula printed beside every number. We are paid by homeowners only and take no fee from contractors. Check a quote from $39, or get a free teardown first.

Questions

How many cfm does a bathroom exhaust fan need?

Seattle's published 2021 residential code, based on the 2021 IRC, lists 50 cfm for a fan that runs when switched on or 20 cfm for one that runs continuously. Larimer County, Colorado, states the same figures under the 2024 IRC. Check your own city's code.

Can a bathroom fan vent into the attic?

Not under the code text Seattle publishes for the 2021 IRC. Section M1501.1 says air shall not be exhausted into an attic, soffit, ridge vent or crawl space, and Section M1505.2 says bathroom exhaust shall be exhausted directly to the outdoors.

How do I check a bath fan's rated airflow?

Ask for the model number and look it up in the ENERGY STAR Product Finder or the HVI-Certified Products Directory. ENERGY STAR records show the airflow at 0.25 inch water gauge, one of the two static pressures in the ENERGY STAR test, along with sones and cfm per watt.

Does duct size matter for a bathroom exhaust fan?

Yes. In the duct length table printed in Seattle's 2021 code, an 80 cfm fan may use at most 4 feet of 4-inch flex duct, but 81 feet of 5-inch flex, with 15 feet deducted for each elbow. Longer runs are allowed if the duct follows the fan maker's design criteria, or if the installer or an approved third party measures the installed airflow with a flow hood, flow grid or other airflow measuring device.

What does an electrician earn per hour?

The BLS May 2025 national wage for electricians is $30.38 median and $52.17 at the 90th percentile per hour. That is pay, not a billing rate: insurance, taxes, vehicles, overhead and profit come on top.

Sources

Every figure above links to the public record it comes from. Wages were looked up in USCCDB v1.0, which carries the BLS file as published. Agency pages, reports and rules are quoted as published on October 16, 2026; check the source for changes.

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