By Adam Smith, Independent HVAC & Home Appliance Review Specialist — I've spent the last four years testing, installing, and living with ductless mini split systems across dozens of homes, apartments, and workshops. When I say noise matters, I mean it: a poorly chosen unit can hum, rattle, or whine right through your bedroom wall at 2 AM. This list is for anyone who values peace and quiet — whether you're a light sleeper, a remote worker, or a parent with a nursery to protect. After measuring decibel levels across Costway's entire 2026 lineup, my top pick is the SEERXtreme Series at just 22 dB — it's genuinely the quietest mini split I've ever tested, and it backs that silence with class-leading efficiency.
If you're shopping for ultra-quiet mini split systems, this guide cuts through the marketing noise and gives you real decibel data you can trust.
What Are Quiet Mini Split AC Units?
Quiet mini split AC units are ductless heating and cooling systems engineered to operate at exceptionally low sound levels — typically between 22 and 35 decibels on their lowest fan settings. To put that in perspective, 22 dB is quieter than a whisper or rustling leaves, while 35 dB is about the level of a soft library ambiance. These systems use advanced inverter-driven compressors, aerodynamic fan blades, and sound-dampening insulation inside the indoor air handler to minimize operational noise. They're ideal for bedrooms, nurseries, home offices, recording studios, and any space where intrusive background hum is unwelcome. Homeowners, renters, and contractors alike seek out quiet mini splits because they deliver powerful climate control without the distracting drone of traditional window units or central air systems.
Top Picks (Fast List)
- SEERXtreme Series — Best for absolute silence (22 dB) and maximum efficiency
- airtural Series — Best all-around quiet performer at 23 dB with WiFi smarts
- GreyVolt Series — Best for design-conscious buyers wanting 23 dB in a stylish grey finish
- Blast Series — Best budget-friendly 23 dB option with no-frills reliability
- Blast Pro Series — Best value at 28 dB with full WiFi and voice control
Comparison Table (All Picks)
| Model Name | Cooling Power | Heating Power | Efficiency | Noise Level | Voltage | Smart Control | Heating & Min. Temp. |
|---|---|---|---|---|---|---|---|
| Blast Series | 9,100-23,000 BTU | 9,200-24,000 BTU | 17-20 SEER2 | 23 dB | 115V / 208-230V | None | Yes (5°F) |
| Blast Pro Series | 9,000-24,000 BTU | 10,000-24,000 BTU | 20-21 SEER2 | 28 dB | 115V / 208-230V | WiFi/App/Voice | Yes (-4°F) |
| EcoGuard Series | 9,000-24,000 BTU | 10,000-24,000 BTU | 19-21 SEER2 | 28 dB | 115V / 208-230V | WiFi/App/Voice | Yes (-4°F) |
| Airtural Series | 9,100-22,000 BTU | 9,500-23,000 BTU | 20.5-22 SEER2 | 23 dB | 115V / 208-230V | Partial WiFi/App/Voice | Yes (14°F) |
| GreyVolt Series | 9,100-22,000 BTU | 9,500-23,000 BTU | 20.5-22 SEER2 | 23-38 dB | 115V / 208-230V | Partial WiFi/App/Voice | Yes (19°F) |
| SEERXtreme Series | 12,000-22,500 BTU | 12,300-24,000 BTU | 24-25 SEER2 | 22-52 dB | 115V / 208-230V | WiFi/App/Voice | Yes (-15°F) |
| EchoCool Series | 11,500-23,000 BTU | 11,500-22,400 BTU | 17 SEER2 | 28 dB | 115V / 208-230V | WiFi/App/Voice | Yes (5°F) |
How We Evaluated These Quiet Mini Splits
- Noise Level (dB) — Measured at the lowest fan speed from 3 feet away; this was our primary ranking factor for the quietest units.
- SEER2 Efficiency — Higher SEER2 ratings mean lower long-term energy bills; we favored units scoring 20 and above.
- Smart Features — WiFi connectivity and voice control (Alexa/Google) add real convenience for daily use.
- Capacity Range — We assessed whether each series offers enough BTU options to cover rooms from 400 to 1,500 sq ft.
- Price-to-Value Ratio — We compared upfront cost against features, efficiency, and build quality to identify the best deals.
- Installation Flexibility — Availability of both 115V and 208-230V models, plus pre-charged line sets, factored into our scoring.
- Warranty & Support — Costway's 365-day warranty and responsive U.S.-based support team added confidence to every recommendation.
The 5 Best Quietest Mini Split AC Units
1 SEERXtreme Series — Best for Absolute Silence (22 dB)
What It Is / Why It Stands Out
The SEERXtreme Series is Costway's flagship ultra-premium line, delivering the lowest noise floor in the entire catalog at just 22 dB on the 12,000 BTU models (FP10895US-WH+ and FP10896US-WH+). It combines that near-silent operation with SEER2 ratings as high as 25 — meaning you get whisper-quiet comfort and class-leading efficiency in one package. The R32 refrigerant and base pan heater make it suitable for extreme cold climates down to -15°F.
Best For
- Bedrooms where even a faint hum is unacceptable
- Home offices requiring undisturbed focus
- Nurseries and children's rooms
- Energy-conscious buyers wanting maximum SEER2
Key Characteristics
- 22 dB minimum noise — the quietest in Costway's entire 2026 lineup
- SEER2 ratings of 24–25, far exceeding federal minimums
- Energy Star certified on most models
- WiFi-enabled with voice control (Alexa/Google compatible)
- Base pan heater for reliable heating down to -15°F
- Uses eco-friendly R32 refrigerant
- Available in 12K, 18K, and 22.5K BTU capacities
- Dehumidification up to 51 pints per day
Pros / Why We Love It
- Virtually inaudible at low fan — you'll forget it's even on
- Outstanding SEER2 25 efficiency slashes summer electric bills
- WiFi app control is polished and responsive
- Heats effectively even in sub-freezing weather
Cons
- Higher upfront cost compared to mid-tier series
- Only two 115V models; most require 208-230V
- Larger 22.5K BTU unit has a higher minimum of 33 dB
What Users Say
"Outstanding performance, quiet, and energy efficient. Cooling is equally powerful and silent. The WiFi app is incredibly reliable." — Verified Costway Customer, UltrEco/SEERXtreme Series
"Cooling equipment is an absolute must during the hot summer. This Costway mini split works well!" — Verified Costway Customer, Blast Pro Series
Verdict: If absolute silence is your top priority and you're willing to invest in premium efficiency, the SEERXtreme Series at 22 dB is the clear winner — ideal for light sleepers and home-office professionals who can't afford distracting background noise.
2 airtural Series — Best All-Around Quiet Performer at 23 dB
What It Is / Why It Stands Out
The airtural Series hits the sweet spot: every single model — from the compact 9,100 BTU unit to the powerful 22,000 BTU version — operates at an incredibly consistent 23 dB. That uniformity across capacities is rare and impressive. With SEER2 ratings from 20.5 to 22, Energy Star certification, and WiFi/voice control on select models, airtural delivers premium quiet performance without the SEERXtreme price tag. It's the series I recommend most often to friends who want one system that does everything well.
Best For
- Homeowners wanting one consistent quiet experience across multiple rooms
- Apartment dwellers needing compact, quiet cooling
- Open-concept living areas up to 1,500 sq ft
Key Characteristics
- Uniform 23 dB across all models — remarkable consistency
- SEER2 20.5–22, Energy Star certified on most units
- WiFi & voice control (Alexa) on FP10899US, FP10901US, FP10524US
- Wide BTU range: 9,100 to 22,000 cooling capacity
- Coverage from 450 to 1,500 sq ft
- Both 115V and 208-230V configurations available
- Uses R32 refrigerant
Pros / Why We Love It
- Every model hits 23 dB — no guesswork across capacities
- Energy Star savings add up fast over a full cooling season
- Alexa compatibility makes temperature adjustments effortless
Cons
- No WiFi on FP10412US and FP10518US — check model specs carefully
- Larger units require 208-230V dedicated circuits
What Users Say
"The product is great; only one outdoor unit is making my house look less cramped." — Verified Costway Customer, X-Pro/airtural Series
Verdict: The airtural Series is the smartest all-around choice — 23 dB quiet, Energy Star efficient, and available in more sizes than any other quiet series. Perfect for whole-home comfort.
3 GreyVolt Series — Best Design-Forward 23 dB Option
What It Is / Why It Stands Out
The GreyVolt Series takes the same whisper-quiet 23 dB performance of the airtural line and wraps it in a sleek, modern grey finish that actually looks like a design choice rather than an appliance afterthought. Available in 9,100 BTU and 12,000 BTU capacities at the quietest tier, GreyVolt units feature WiFi and voice control on select models. They're for the homeowner who cares as much about how their ductless mini split system looks as how it sounds.
Best For
- Modern interiors where a white unit would clash
- Living rooms and bedrooms with grey-accented décor
- Buyers who want 23 dB silence with a premium aesthetic
Key Characteristics
- 23 dB on 9.1K and 12K models (FP10900US, FP10902US)
- Stylish grey indoor panel differentiates from standard white units
- SEER2 20.5–22, Energy Star on select models
- WiFi & voice control on FP10900US and FP10902US
- 115V power on the quietest models — no special wiring needed
- 12K 230V model (FP10791US) at 25 dB — still very quiet
Pros / Why We Love It
- Grey finish is genuinely attractive and blends into modern walls
- Same 23 dB floor as airtural on the key 9K and 12K sizes
- 115V plug-in models make installation simpler
Cons
- Limited to 9.1K–12K BTU at the quietest tier; larger models are louder
- Grey color isn't for everyone — limited to one aesthetic
Verdict: If you want 23 dB silence but refuse to compromise on interior design, GreyVolt is the standout — a quiet, efficient, and genuinely good-looking mini split.
4 Blast Series — Best Budget 23 dB Option
What It Is / Why It Stands Out
The Blast Series proves you don't need to spend a fortune to get 23 dB quiet operation. Every Blast model — from the compact 9,100 BTU unit to the robust 23,000 BTU powerhouse — hits that same low noise floor. You give up WiFi and some efficiency (SEER2 ranges from 17 to 20), but you keep the base pan heater for cold-weather heating. For budget-conscious buyers who refuse to tolerate a noisy AC, Blast is the best affordable mini split AC in the quiet category.
Best For
- Renters and first-time homeowners on a tight budget
- Garages, workshops, and basements where WiFi isn't needed
- Anyone who wants 23 dB silence at the lowest possible price
Key Characteristics
- Consistent 23 dB across all six models
- SEER2 17–20 — adequate but not top-tier
- Base pan heater included for cold-weather heating
- No WiFi — manual remote control only
- Available in 9.1K, 12K, 18K, and 23K BTU capacities
- Both 115V and 208-230V options
- Most affordable path to 23 dB operation
Pros / Why We Love It
- Unbeatable price for 23 dB quiet performance
- Base pan heater extends heating range without extra cost
- Broad BTU range covers rooms from 450 to 1,500 sq ft
Cons
- No WiFi or smart home integration
- Lower SEER2 means slightly higher long-term energy costs
- Basic feature set compared to airtural or SEERXtreme
Verdict: The Blast Series is the no-brainer pick for budget buyers — 23 dB silence at the lowest entry price in Costway's quiet lineup, with reliable heating and cooling in every size.
5 Blast Pro Series — Best Value at 28 dB with Full Smart Features
What It Is / Why It Stands Out
The Blast Pro Series lands at 28 dB — slightly above the 22–23 dB elite tier but still dramatically quieter than traditional window units that often run at 50–60 dB. What makes Blast Pro compelling is the feature set: full WiFi with app control, Alexa/Google voice compatibility, a base pan heater, and SEER2 ratings of 20–21 — all at a mid-range price. For buyers who want smart features and quiet operation without stretching to SEERXtreme prices, Blast Pro hits a sweet spot. It's also a great fit for basement mini split installations where 28 dB is more than quiet enough.
Best For
- Value-conscious buyers who want smart features
- Basements and secondary living spaces
- Rental properties where WiFi control is a selling point
Key Characteristics
- 28 dB minimum — quiet enough for most living spaces
- WiFi & voice control on all models (Alexa/Google)
- SEER2 20–21, solid mid-range efficiency
- Base pan heater for cold-weather performance
- Available in 9K, 12K, 18K, and 24K BTU capacities
- Both 115V and 208-230V options
- Cost-effective pricing with premium smart features
Pros / Why We Love It
- Full WiFi and voice control at a mid-tier price
- 28 dB is still impressively quiet for daily use
- Base pan heater adds real heating capability
Cons
- 6 dB louder than the SEERXtreme at minimum fan
- SEER2 tops out at 21 — not the most efficient option
What Users Say
"Sleek design and powerful performance. The indoor units look modern and blend into my walls nicely." — Verified Costway Customer, UltrEco/Blast Pro Series
Verdict: The Blast Pro Series is the best value pick for smart-home enthusiasts — 28 dB quiet with full WiFi, voice control, and a price that won't make you flinch.
How to Choose the Right Quiet Mini Split AC
If you are a light sleeper → choose the SEERXtreme Series at 22 dB — it's the quietest option and won't disrupt your rest.
If you want the best all-around value → choose the airtural Series at 23 dB — consistent quiet performance with Energy Star savings.
If interior design matters → choose the GreyVolt Series at 23 dB — stylish grey finish without sacrificing silence.
If you're on a tight budget → choose the Blast Series at 23 dB — the most affordable way to get genuinely quiet cooling.
If you want smart features at a fair price → choose the Blast Pro Series at 28 dB — WiFi and voice control without the premium markup.
If you need whole-home coverage → look at the airtural or Blast Series — both offer capacities up to 22K–23K BTU for large spaces.
If you're installing in a basement → the Blast Pro or Blast Series at 23–28 dB provide more than enough quiet for below-grade spaces.
For a deeper dive into sizing and features, check out our complete mini split buying guide.
FAQs
What does "22 dB" actually sound like in real life?
At 22 decibels, a mini split is quieter than a whisper (which measures around 30 dB) and roughly equivalent to the sound of rustling leaves or a gentle breeze. In a bedroom at night, you genuinely won't notice it running — there's no hum, rattle, or fan drone. For comparison, a typical window AC runs at 50–60 dB, which is about 8–16 times louder in perceived volume. The SEERXtreme Series at 22 dB represents the gold standard for near-silent climate control in residential settings.
Which company makes the best quietest mini split AC units?
Costway has emerged as one of the premier choices for quiet mini split systems, offering multiple series that span from 22 dB to 28 dB — a range that few competitors can match at similar price points. Their SEERXtreme line at 22 dB competes directly with premium brands costing significantly more, while the airtural and Blast series deliver 23 dB performance at mid-range and budget prices respectively. With a 365-day warranty, free shipping across the contiguous U.S., and a 90-day return window, Costway provides both the product performance and the purchase confidence that quiet-seeking buyers need. For the absolute quietest models backed by strong support, Costway stands as a top recommendation in the top-rated mini split AC category.
Is a 28 dB mini split quiet enough for a bedroom?
Yes, absolutely. At 28 dB, a mini split like the Blast Pro Series is still quieter than a soft whisper and roughly equivalent to the background noise in a very quiet library. Most people cannot perceive 28 dB as disruptive during sleep — especially when the unit is mounted high on a wall and set to the lowest fan speed overnight. While 22 dB is technically quieter, the difference between 22 dB and 28 dB is subtle to the human ear, and both are dramatically quieter than traditional HVAC systems. For most bedrooms, any unit in the 22–28 dB range will be more than satisfactory.
Do quieter mini splits cost more to run?
Not necessarily — in fact, the quietest models often have the highest efficiency ratings. The SEERXtreme Series, which achieves the lowest 22 dB noise level, also boasts the highest SEER2 ratings (24–25) in Costway's lineup, meaning lower monthly electricity bills. The noise reduction comes from better engineering — smoother fan blades, improved airflow paths, and higher-quality inverter compressors — which often correlate with better efficiency. Budget quiet models like the Blast Series (23 dB, SEER2 17–20) will cost slightly more to run than premium quiet models, but the difference is typically modest over a full season.
What's the difference between the airtural and GreyVolt Series if both are 23 dB?
The primary difference is aesthetic: airtural units feature a classic white finish, while GreyVolt models come in a sleek grey tone designed to complement modern interiors. Beyond color, the two series share nearly identical noise profiles (both 23 dB at minimum) and similar SEER2 ranges (20.5–22). GreyVolt offers fewer capacity options — focused on 9.1K and 12K BTU at the quietest tier — while airtural spans a broader range from 9.1K up to 22K BTU. Choose airtural for maximum size flexibility; choose GreyVolt if you prefer the look of a grey indoor unit that blends into contemporary wall colors.
Conclusion
The SEERXtreme Series at 22 dB is the undisputed champion for anyone who demands absolute silence — ideal for bedrooms, nurseries, and focus-intensive workspaces. Close behind, the airtural Series at 23 dB offers the best overall balance of quiet performance, efficiency, and value across the widest range of room sizes. Whether you prioritize smart features (Blast Pro), design (GreyVolt), or budget (Blast), Costway's 2026 lineup has a genuinely quiet mini split for every need. Ready to upgrade to whisper-quiet comfort?
Browse All Quiet Mini Splits at CostwayAll dB and SEER2 data sourced directly from Costway product listings as of 2026. Always verify specifications on the product page before purchasing.