# Best bathroom exhaust fan: the maker spec sheets and the ENERGY STAR dataset sort them by CFM at a stated static pressure, sones, duct size and watts, and the duct to the outside decides before any of that > HVI sizes a bathroom at 1 CFM per sq ft up to 100 sq ft. Panasonic FV-0511VF1 prints 110 CFM, 0.8 sones and 10.2 W at 0.1 in. w.g.; Broan BEL8 80 CFM, 1.5 sones. | | | |---|---| | Source | https://ownerspec.com/air/reviews/best-bathroom-exhaust-fan/ | | Publisher | OwnerSpec (https://ownerspec.com/) | | Published | 2026-10-09 | | Updated | 2026-10-09 | | Facts verified | 2026-10-09 | | Disclosure | Contains affiliate links. OwnerSpec may earn a commission at no cost to the reader. | --- ## Short answer For a bathroom up to 100 sq ft, HVI's sizing rule is 1 CFM per square foot, and the pick on that rule is the Panasonic FV-0511VF1 WhisperFit: its HVI-certified submittal sheet lists 110 CFM, 0.8 sones and 10.2 W at 0.1 in. w.g. on a 4 in duct, and Panasonic's page says it installs from below the ceiling. The runner-up is the same fan with a sensor, the FV-0511VFC1, which switches itself on from relative humidity and temperature and runs a 20-minute delay timer. The Broan BEL8 is the cheaper no-attic swap at 80 CFM and 1.5 sones in the ENERGY STAR dataset, and the KAZE SEP120H covers a 120 sq ft room at 120 CFM and 0.3 sones with a 50% to 80% RH set-point. Skip every fan here if the bathroom has no duct to the outside: the U.S. Department of Energy's job aid says a bath fan must exhaust to the exterior, never into an attic or crawl space. ## Fact sheet - **Answer:** HVI sizes a bathroom up to 100 sq ft at 1 CFM per square foot, and on that rule the Panasonic FV-0511VF1 is the pick: its HVI-certified sheet lists 110 CFM, 0.8 sones and 10.2 W at 0.1 inches of water gauge on a 4 in duct, installed from below the ceiling. The FV-0511VFC1 adds a condensation sensor with a 20-minute delay timer; the Broan BEL8 lists 80 CFM and 1.5 sones. - **Comparison basis:** Panasonic's HVI-certified submittal and architectural sheets for the FV-0511VF1, FV-0511VFC1, FV-0510VS1 and FV-0511VQ1, Panasonic's product pages for the FV-0511VK3, KAZE's SEP120H product page and the ENERGY STAR Certified Ventilating Fans dataset, compared on CFM at a stated static pressure, sones, duct size, watts, CFM per watt, humidity sensing and whether the maker says it installs without attic access, against HVI's 1 CFM per square foot sizing rule. - **Assumptions:** The bathroom is 100 sq ft or less; HVI sizes larger rooms by fixture instead; A duct to the outside exists or will be built; DOE's job aid requires bath fans to exhaust to the exterior; CFM figures are compared at the static pressure each source prints; the ENERGY STAR column is the maximum-speed rating rounded down to 10 CFM - **Method:** OwnerSpec compared manufacturer-published specifications and the ENERGY STAR dataset read on 2026-10-09 and confirmed each listing in stock the same day; it did not install, run or measure any fan, prints no health outcome, and reports only the figures the cited document states. - **Primary source:** [HVI, Bathroom Ventilation](https://www.hvi.org/resources/publications/bathroom-ventilation/) (manufacturer or vendor document) - **Facts verified:** 2026-10-09 - **Last updated:** 2026-10-09 - **Canonical URL (cite this):** https://ownerspec.com/air/reviews/best-bathroom-exhaust-fan/ If the fan duct ends in the attic, a soffit or nowhere at all, close this page and get the duct run outside first: no fan below fixes a fan with nowhere to blow. ## How was this shortlist built? Every figure here is a manufacturer-published specification or an ENERGY STAR dataset row read on 2026-10-09 from the document named beside it; nothing was installed, run or measured, and every listing was confirmed in stock the same day. Fans were compared on CFM at a stated static pressure, sones, duct size, watts, CFM per watt, humidity sensing and whether the maker says it fits from below the ceiling. Three gaps are stated, not filled. Broan-NuTone's pages and PDFs would not load, so Broan figures come only from the ENERGY STAR dataset; KAZE's SEP120H page prints no wattage, pressure basis, HVI, UL or ENERGY STAR line; Delta Breez is absent because no Delta sheet was opened. A sone is the loudness unit on fan sheets, lower being quieter; static pressure, in inches of water gauge (in. w.g.), is the duct resistance the fan was rated against. ## How many CFM does the bathroom need? HVI's bathroom ventilation guidance sizes rooms up to 100 sq ft at 1 CFM per square foot, which it calls roughly eight air changes per hour. Over 100 sq ft, HVI sizes by fixture: 50 CFM each for the toilet, shower and bathtub, 100 CFM for a jetted tub. HVI also says to leave the fan running 20 minutes after use, which is the reason the sensor and timer models exist. The fan is the bathroom fix only. If [condensation on the inside of the windows](/air/guides/condensation-on-inside-of-windows-winter/) shows up in bedrooms too, the whole house is wet, and the [indoor humidity by outdoor temperature calculator](/air/calculators/indoor-humidity-by-outdoor-temperature/) gives the target before a fan or a dehumidifier is bought. ## How do the fans compare on paper? The ENERGY STAR dataset prints a maximum-speed rating rounded down to 10 CFM plus airflow at 0.25 in. w.g.; it is not the same test as the maker's 0.1 in. w.g. column, so both are shown. | Fan | CFM at 0.1 in. w.g. (maker) | ENERGY STAR rating / at 0.25 | Sones | Duct | W at 0.1 (maker) | CFM/W (ENERGY STAR) | Humidity sensor | Fits from below | |---|---|---|---|---|---|---|---|---| | Panasonic FV-0511VF1 | 110 (50/80/110 selectable) | 110 / 112.9 | 0.8 at 110 CFM | 4 in, 3 in with adapter | 10.2 | 11.0, Most Efficient | No | Yes, 5-5/8 in housing | | Panasonic FV-0511VFC1 | 110 (50/80/110) | 110 / 112.9 | 0.8 at 110 CFM | 4 in, 3 in with adapter | 10.2 | 11.0, Most Efficient | Yes, 20-minute delay | Yes | | Panasonic FV-0510VS1 | 100 (50/80/100) | 100 / 102.9 | 0.9 at 100 CFM | 4 in oval | 11.1 | 9.2 | No | Not stated; 3-3/8 in housing, ceiling or wall | | Panasonic FV-0511VK3 | Not opened (certified at 0.5 in. w.g.) | 110 / 111.4 | 0.1 | 6 in or 4 in (two ENERGY STAR rows) | Not opened | 16.7 (6 in), 11.4 (4 in), Most Efficient | Optional FV-CSVK1 module | Yes | | Panasonic FV-0511VQ1 WhisperCeiling | 110 (50/80/110) | 110 | Under 0.3 at all speeds | 4 in or 6 in adapter | 10.6 | 10.7, Most Efficient | No | Not stated | | Broan-NuTone BEL8 | Not readable | 80 / 70.5 | 1.5 | 4 in | Not readable | 4.1 | No (BES8 is the sensing sibling) | Sold as roomside; maker page not readable | | KAZE SEP120H | 120 (pressure basis not printed) | Not in the dataset | 0.3 | 6 in adapter | Not printed | Not printed | Yes, 50 to 80% RH, 5 to 30 min delay | Not stated | The FV-0511VQ1 is in the table only: its listing was out of stock on 2026-10-09. ## Why is the CFM on the box not the CFM you get? Panasonic's sheet shows the loss. The FV-0511VF1 on a 4 in duct lists 110 CFM at 0.1 in. w.g., 111 at 0.25 and 109 at 0.375, because the ECM motor speeds up against pressure. On the 3 in adapter the same fan lists 94 CFM at 0.25 and 69 at 0.375, and the sone figure at 0.1 rises from 0.8 to 2.0. A 0.1 sone fan on a crushed or undersized duct is louder and weaker than a 1.5 sone fan on a short, straight 4 in run, and DOE's job aid says the duct must be at least as large as the fan outlet, with no reducers. ENERGY STAR only requires that airflow at 0.25 in. w.g. is at least 70% of the figure at 0.1, caps 10 to 200 CFM fans at 2.0 sones and sets a floor of 3.5 CFM/W for 90 to 200 CFM fans. ## Panasonic FV-0511VF1 WhisperFit: buy it or skip it? Buy it if you are replacing a fan from below the ceiling. Panasonic's page says the WhisperFit is designed for retrofit and it fits any ceiling at least 5-5/8 in deep; the submittal sheet lists 110 CFM, 0.8 sones, 10.2 W and 11.0 CFM/W at 0.1 in. w.g. on a 4 in duct, UL listing for a tub or shower enclosure with GFCI protection, and a built-in backdraft damper. The submittal sheet prints a 3-year parts warranty. The flaw is the 3 in adapter in the box: it tempts a reuse of the old duct, and the sheet shows what that costs. Skip it if you want a light or a sensor: the VFC1 is the sensor version and the BEL8 has the light. ## Panasonic FV-0511VFC1 (condensation sensor): buy it or skip it? Buy it if the fan in your house gets switched off with the light. Panasonic's page says the sensor reads relative humidity and temperature to anticipate the dew point, runs a 20-minute delay timer, and reactivates when the level drops 5% below the trigger. The airflow table is the FV-0511VF1's: 110 CFM and 0.8 sones at 0.1 in. w.g. The flaw is that no opened Panasonic document prints the VFC1's set-point range, so this page states none; the KAZE prints 50% to 80% RH. Skip it if someone already runs the fan 20 minutes after every shower: the sensor buys nothing over the VF1. ## Panasonic FV-0510VS1 WhisperValue: buy it or skip it? Buy it if the ceiling cavity is shallow or the fan must go in a wall. Panasonic's architectural spec lists 100 CFM at 0.1 in. w.g. with 0.9 sones and 11.1 W, a 4 in oval duct and UL listing for ceiling or wall mount and for a tub or shower enclosure with GFCI. The product page prints a 3-3/8 in housing depth. The flaw is the top speed: 100 CFM is the ceiling, and the ENERGY STAR dataset lists it at 9.2 CFM/W without the Most Efficient flag. Skip it if the room is over 100 sq ft. ## Broan-NuTone BEL8 Roomside: buy it or skip it? Buy it if the budget is the constraint and the room is 80 sq ft or less. The ENERGY STAR dataset lists the BEL8 at 80 CFM, 1.5 sones, a 4 in duct, 4.1 CFM/W and 70.5 CFM at 0.25 in. w.g., and it is the only fan on this page with a light. The flaw is twofold. At 1.5 sones it is the loudest fan in the table, and at 4.1 CFM/W it uses roughly 2.7 times the watts per CFM of the FV-0511VF1. Broan's pages were unreadable this session, so the watts, warranty and no-attic-access claim rest on the listing alone. Skip it if the bathroom has a separate shower and tub: HVI's fixture rule asks for 100 CFM. ## Panasonic FV-0511VK3 WhisperGreen Select: buy it or skip it? Buy it if the duct run is long or already 6 in. Panasonic's page lists a 50-80-110 CFM selector, install without attic access and HVI-certified CFM at 0.5 in. w.g. The ENERGY STAR dataset lists 0.1 sones, 16.7 CFM/W on a 6 in duct and 11.4 CFM/W on 4 in, with the Most Efficient flag. The flaw is the module list. The fan ships without a sensor; the FV-CSVK1 condensation module (30% to 80% RH in 10% steps per the brochure) and the Wi-Fi module are separate buys, and no opened document printed the VK3's watts per speed. Skip it if the duct is a short 4 in run to the wall: the VF1 does the same 110 CFM for less. ## KAZE SEP120H: buy it or skip it? Buy it if the bathroom is between 100 and 120 sq ft and you want the sensor built in with a printed range. KAZE's page lists 120 CFM, 0.3 sones, a built-in 6 in duct adapter, a 50% to 80% RH set-point, a 5 to 30 minute delay timer and a three-year warranty. The flaw is what the page does not print: no wattage, no pressure basis for the 120 CFM, no HVI, UL or ENERGY STAR line, and the SEP120H is absent from the ENERGY STAR dataset. KAZE's page also does not say whether it fits from below the ceiling. Skip it under 100 sq ft, where the Panasonic sheets print more. **Measure before you buy** Two numbers decide between every fan above: the floor area, which sets the CFM at HVI's 1 per square foot, and the duct diameter at the fan, which decides whether the 4 in or the 3 in adapter column applies. If the steam is the shower itself, the [shower head review](/plumbing/reviews/best-shower-head/) lists flow rates and the [shower cost calculator](/plumbing/calculators/shower-water-and-energy-cost-calculator/) prices a shorter one. ## Who should skip every fan on this page? **Anyone with no duct to the outside.** DOE's job aid says bath fans must exhaust to the exterior and warns that moisture blown into an attic or crawl space can cause mold and rot. The duct must match the fan outlet size and, where the local authority requires it, carry R-8 insulation through unconditioned space. **Anyone whose damp is in the basement.** A fan empties one room. Size that problem with the [dehumidifier size calculator](/plumbing/calculators/dehumidifier-size-calculator/) and read the [basement dehumidifier review](/plumbing/reviews/best-dehumidifier-for-basement/) instead. ## What goes wrong? **The duct is 3 in.** Panasonic's sheet prints the penalty: 69 CFM instead of 109 at 0.375 in. w.g. **The fan is sized to the box, not the room.** An 8 by 12 ft bathroom is 96 sq ft and needs 96 CFM on HVI's rule. **The fan runs only as long as the shower.** HVI's figure is 20 minutes after use. ## The picks - **Panasonic FV-0511VF1 WhisperFit DC (50-80-110 CFM)**: Replacing an old fan from below the ceiling, no attic access (Panasonic submittal sheet, HVI data on a 4 in duct at 0.1 in. w.g.: 110 CFM, 0.8 sones, 10.2 W, 11.0 CFM/W; fits ceilings at least 5-5/8 in deep per Panasonic's page; ENERGY STAR dataset flags it Most Efficient; 3-year parts warranty on the submittal sheet) Amazon: https://www.amazon.com/dp/B0973N9G21/?tag=ownerspec-20 - **Panasonic FV-0511VFC1 WhisperFit DC with condensation sensor**: Nobody in the house runs the fan after a shower (Same HVI table as the FV-0511VF1 (110 CFM, 0.8 sones, 10.2 W at 0.1 in. w.g.); Panasonic's page: sensor reads relative humidity and temperature, 20-minute delay timer, reactivates when the level drops 5% below the trigger; retrofit and new construction) Amazon: https://www.amazon.com/dp/B09739RB73/?tag=ownerspec-20 - **Panasonic FV-0510VS1 WhisperValue DC (50-80-100 CFM)**: Budget pick for a bathroom up to 100 sq ft with a shallow ceiling cavity (Panasonic architectural spec, HVI data at 0.1 in. w.g.: 100 CFM, 0.9 sones, 11.1 W, 9.2 CFM/W; 3-3/8 in housing depth, 4 in oval duct, ceiling or wall mount; ENERGY STAR dataset lists it but not as Most Efficient) Amazon: https://www.amazon.com/dp/B06W2LB17J/?tag=ownerspec-20 - **Broan-NuTone BEL8 Roomside (80 CFM, LED light)**: Cheapest no-attic-access swap with a light, for a bathroom up to 80 sq ft (ENERGY STAR Certified Ventilating Fans dataset: 80 CFM, 1.5 sones, 4 in duct, 4.1 CFM/W, 70.5 CFM at 0.25 in. w.g.; Broan's own pages and PDFs were unreadable this session, so watts, warranty and housing size are not printed here) Amazon: https://www.amazon.com/dp/B0DH5HM61V/?tag=ownerspec-20 - **Panasonic FV-0511VK3 WhisperGreen Select (50-80-110 CFM)**: Premium pick for a long or 6 in duct run and the lowest sone figure on the page (ENERGY STAR dataset: 110 CFM, 0.1 sones, 16.7 CFM/W on 6 in duct and 11.4 CFM/W on 4 in, Most Efficient; Panasonic's page: installable without attic access, HVI-certified CFM at 0.5 in. w.g.; humidity sensor FV-CSVK1 and Wi-Fi are plug-in modules sold separately) Amazon: https://www.amazon.com/dp/B0D7QRDTVF/?tag=ownerspec-20 - **KAZE SEP120H humidity-sensing (120 CFM, 0.3 sones)**: Bathroom of 100 to 120 sq ft that wants the sensor built in (KAZE product page: 120 CFM, 0.3 sones, up to 120 sq ft, built-in 6 in duct adapter, humidity set-point 50% to 80% RH, 5 to 30 minute delay timer, three-year warranty; the page prints no wattage, static-pressure basis, HVI, UL or ENERGY STAR for this model) Amazon: https://www.amazon.com/dp/B07T2MLLGK/?tag=ownerspec-20 ## Frequently asked questions ### How many CFM does a bathroom exhaust fan need? HVI's bathroom ventilation guidance sizes a bathroom up to 100 sq ft at 1 CFM per square foot, which it describes as roughly eight air changes per hour. Above 100 sq ft it sizes by fixture: 50 CFM each for a toilet, shower and bathtub and 100 CFM for a jetted tub. HVI also recommends leaving the fan running 20 minutes after use. ### Why does the same fan list two different CFM numbers? Makers rate airflow at a stated static pressure, and the number falls as duct resistance rises. Panasonic's FV-0511VF1 sheet lists 110 CFM at 0.1 in. w.g. on a 4 in duct, 111 at 0.25 and 109 at 0.375, but on the 3 in adapter the same fan drops to 94 CFM at 0.25 and 69 at 0.375. Compare fans at the same pressure or not at all. ### What does ENERGY STAR require of a bathroom fan? ENERGY STAR's ventilating fan criteria require that airflow measured at 0.25 in. w.g. is at least 70% of the airflow at 0.1 in. w.g., a maximum of 2.0 sones for fans rated 10 to 200 CFM, and a minimum efficacy of 2.8 CFM per watt for 10 to 89 CFM fans and 3.5 CFM per watt for 90 to 200 CFM fans. ### Can a bathroom fan vent into the attic? No. The U.S. Department of Energy's job aid for bath fan ducting says bath fans must exhaust to the exterior of the home, and that exhausting the moisture into an attic or crawl space can cause mold and rot. It also says the duct must be at least as large as the fan outlet and, where the local authority requires it, insulated to at least R-8 through unconditioned space. ### Which bathroom fan can be installed without attic access? Panasonic's WhisperFit page says the FV-0511VF1 is designed for retrofit and installs from below the ceiling, for ceilings at least 5-5/8 in deep. Panasonic's WhisperGreen Select page says the FV-0511VK3 is installable without attic access. The Broan BEL8 Roomside is sold as a no-attic-access fan, but Broan's own pages were unreadable this session, so that claim is not confirmed from a maker document here. ## Sources - [HVI, Bathroom Ventilation](https://www.hvi.org/resources/publications/bathroom-ventilation/) (manufacturer or vendor document) - [ENERGY STAR, Ventilating Fans key product criteria](https://www.energystar.gov/products/heating_cooling/fans_ventilating/key_product_criteria) (government or regulatory source) - [ENERGY STAR Certified Ventilating Fans dataset (data.energystar.gov, 8dv7-nngq)](https://data.energystar.gov/resource/8dv7-nngq.json) (government or regulatory source) - [Panasonic, WhisperFit DC submittal sheets, all models (FV-0511VF1, FV-0511VFC1)](https://constructioninstruction.com/wp-content/uploads/2021/06/Panasonic-WhisperFit-DC-Submittal-Sheets_All-Models.pdf) (manufacturer or vendor document) - [Panasonic, WhisperFit DC fan FV-0511VF1 product page](https://iaq.na.panasonic.com/ventilation/fans/whisperfit-dc) (manufacturer or vendor document) - [Panasonic, WhisperFit DC condensation model FV-0511VFC1 product page](https://iaq.na.panasonic.com/ventilation/fans/whisperfit-dc-condensation) (manufacturer or vendor document) - [Panasonic, WhisperValue DC FV-0510VS1 product page](https://iaq.na.panasonic.com/ventilation/fans/whispervalue-50-80-100-cfm) (manufacturer or vendor document) - [Panasonic, FV-0510VS1 architectural specifications](https://media.distributordatasolutions.com/web_panasonic_us/2023q4/documents/107b6b433992cbd9165334f8bd637f58326853dc.pdf) (manufacturer or vendor document) - [Panasonic, FV-0511VQ1 engineering bulletin](https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Panasonic-FV-0511VQ1-Engineering-Bulletin.pdf) (manufacturer or vendor document) - [Panasonic, WhisperGreen Select FV-0511VK3 product page](https://iaq.na.panasonic.com/ventilation/fans/whispergreen-select-fv-0511vk3) (manufacturer or vendor document) - [Panasonic, WhisperGreen Select brochure (FV-0511VK3 family)](https://s1.img-b.com/build.com/mediabase/specifications/panasonic/2014414/panasonic-fv-0511vks3-specification-sheet.pdf) (manufacturer or vendor document) - [KAZE Appliance, SEP120H product page](https://kazeappliance.com/products/sep120h) (manufacturer or vendor document) - [U.S. Department of Energy, Job Aid 18-1: Install Exhaust Fan Flex Duct (Bath Fan Only)](https://www.energy.gov/sites/default/files/2022-06/job-aid-18-1_install-exhaust-fan-flex-duct-bath-fan-only.pdf) (government or regulatory source) --- Citation: OwnerSpec, "Best bathroom exhaust fan: the maker spec sheets and the ENERGY STAR dataset sort them by CFM at a stated static pressure, sones, duct size and watts, and the duct to the outside decides before any of that", https://ownerspec.com/air/reviews/best-bathroom-exhaust-fan/, facts verified 9 October 2026. 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