Free Mini-Split Calculator for Bay Area Homes
Get a starting size estimate for a room, ADU or garage conversion. The tool uses preset climate and construction values, plus your room details. We measure the rooms and check the model data before choosing equipment.
Use this tool to estimate room capacity, then review equipment options, electrical work and permit requirements with your installer.
Where is the property
Tell us about the room
Sizing one room? For an ADU, use a single "Studio / ADU" preset. For multiple rooms (whole-house multi-zone), we review the room measurements during a free installation assessment.
The estimate for your 200 sqft bedroom in San Ramon (CZ 12) is 6k BTU/h. This is a planning estimate based on the tool's assumptions. It chooses from 6k to 36k options. We measure the room and check the indoor and outdoor models before recommending equipment.
Note: 6k is the smallest option in this tool. For a small space, check the model minimum output and room load before selecting equipment.
What to check before choosing a mini-split kit
Kits differ in their connections, commissioning steps and warranty conditions. Start with the manual for the kit you are considering. Here is what to check:
Refrigerant problems
The installation manual lists the allowed line lengths, connections and refrigerant charge. Follow the instructions for your system; precharged lines and conventional piping need different startup work.
Line set length wrong
Read the manual before cutting, joining or routing a line set. Some precharged systems allow extra line to be coiled. Follow the routing and coiling instructions for your kit.
Electrical done wrong
The nameplate and install manual say what circuit and disconnect the unit needs. We check whether your panel can carry it and what electrical work the installation needs.
No permits, failed inspections
Ask the local building department which permits, energy-code documents and inspections your project needs. Sort those out before installation starts.
Warranty terms
As a Mitsubishi Electric Diamond Contractor, we register your M-Series or P-Series system for the Mitsubishi Electric 12-year parts and 12-year compressor limited warranty (the HM, WR, HX and WX wall-mounted series top out at 10 years). We register all indoor and outdoor units within 90 days of installation. This coverage applies to a single-family home while the original owner continues to live there and is not transferable. Our standard workmanship warranty is 2 years.
Condensate management
We check the drain route from the indoor unit and whether it can drain by gravity or needs a pump. The model manual sets the drainage and overflow-protection requirements.
Precharged line sets have their own connection and routing instructions. Some allow extra line to be coiled. Check your kit’s manual before changing a line, and read its warranty terms before starting work.
Same capacity, very different installs
Two units with the same rated output can need different mounting space, drains and service access. Check how each would fit your room and which outdoor units the manufacturer approves with it.
Wall-mounted
Mounted high on a wall, where you can see the indoor unit.
One-way ceiling cassette
Recessed ceiling unit with a directional air outlet.
Four-way ceiling cassette
Recessed ceiling unit with outlets facing several directions.
Floor-mounted
Console installed low on a wall, with clearance around its air outlets.
Concealed ducted mini
Concealed air handler connected to room registers through ducts.
What's actually in a mini-split install
Your written estimate lists the equipment and work for your property. Use these items to compare what each quote includes.
Outdoor + indoor units
- ·Inverter-driven outdoor unit (heat pump or AC-only)
- ·Head(s) matched to your room sizes
- ·New ductless installations: Mitsubishi Electric
- ·Equipment selected for the room load, layout and design temperature
Line sets & commissioning
- ·Copper line set sized to your specific run length
- ·Evacuation and commissioning steps specified for the selected system
- ·Leak checks using the method required by the manufacturer
- ·Refrigerant charge adjusted for your line set length per manufacturer specs
Power infrastructure
- ·Supply circuit specified for the selected equipment
- ·Disconnect and protection required for the installation
- ·Possible sub-panel for ADU/garage detached structures
- ·Panel capacity assessed before any electrical work is priced
Title 24 & building permit
- ·Applicable permits confirmed with the local building department
- ·Title 24 compliance documentation for the install
- ·Inspection by city official upon completion
- ·ADU plan review and fees confirmed for the project
Condensate & mounting
- ·Condensate drain with proper slope and overflow protection
- ·Condensate pump (if gravity drain isn't possible)
- ·Outdoor unit pad or wall bracket, vibration isolators
- ·Line set cover (paintable plastic raceway) for clean exterior look
Warranty & commissioning
- ·Manufacturer coverage checked against model, registration and ownership terms
- ·Standard ADRIUM workmanship warranty: 2 years
- ·System commissioning report (refrigerant, electrical, controls)
- ·Installation and model documentation for future reference
ADUs & garage conversions: special considerations
A separate system can give an ADU its own temperature control. Check the planned construction, room loads and installation routes before selecting equipment. These project details need review:
2029 furnace emission standard
Air District Rule 9-4 sets a zero-NOx standard for covered furnaces manufactured after January 1, 2029. It does not require replacing a working furnace. Check the equipment scope, current rule updates and local permit requirements for your ADU. Air District rule information.
Check the electrical supply
We check the existing electrical service, the ADU's planned loads and the circuit route. Then we list any new feeder, sub-panel or other electrical work in the estimate.
Check plug-in options
Check that the plug-in model can heat and cool the room. Its manual lists the circuit it needs; we check whether the existing supply is suitable.
Check the planned insulation
Bring the planned wall, ceiling, window and floor details. We use those along with room measurements to size the indoor unit.
One head or two?
We look at the floor plan, doors and airflow, and ask which rooms need separate controls. Then we size each zone and check the approved indoor and outdoor unit combinations.
Confirm the project review
Ask the local building department what to submit and which inspections are needed. Check its current processing time before setting an installation date.
Air District rules for new equipment
Checked September 28, 2026. These dates come from the rules adopted in March 2023 and refer to equipment manufacture dates. They apply within the Air District's jurisdiction to the equipment defined by each rule. Working equipment does not have to be removed. Check current amendments before selecting a replacement.
Covered small tank water heaters
Rule 9-6 sets the adopted zero-NOx standard for covered storage water heaters with heat input of 75,000 BTU/h or less manufactured after this date. Mobile-home units are exempt. Proposed 2026 amendments remain under consideration.
Covered furnaces
Rule 9-4 sets the adopted zero-NOx standard for covered furnaces manufactured after this date. The furnace heat-input limit is below 175,000 BTU/h; mobile-home furnaces are excluded. The separate 65,000 BTU/h limit concerns cooling capacity in combination units.
Covered larger water heaters and boilers
Rule 9-6 sets the adopted zero-NOx standard for covered water heaters and boilers with heat input from 75,001 to 2,000,000 BTU/h manufactured after this date. Check the rule definitions and exemptions for the equipment being considered.
For your project: confirm the appliance type, nameplate rating, manufacture date and current rules with your installer. A heat pump is one option; electrical capacity, sizing and permit requirements still need to be checked. Read the Air District updates before choosing equipment.
Check rebates before budgeting
Use the current program terms for your address, utility account and selected equipment. Confirm eligibility and any reservation deadline before work begins. This tool does not calculate or guarantee a rebate.
Check the program administrator for current funding, household eligibility and reservation requirements.
Check current program terms and reservation availability for the proposed equipment and project.
Home+ has ended. See BayREN’s retirement notice. Current EASE Home support has different requirements.
Gas-heating replacement: $2,000 standard or $3,000 income-qualified. Electric-resistance replacement: $500 standard or $1,500 income-qualified. Reserve with SVCE before installation and confirm the approved amount and equipment.
A qualifying gas-heating replacement has a $1,500 base rebate, plus $1,000 for eligible CARE/FERA customers. Apply to WestLight within 90 days after installation. Confirm account and equipment eligibility first.
Check the current city or utility program for the service address; funding, qualifying equipment and application steps vary.
No-charge energy-saving upgrades and repairs for qualifying households. PG&E does not publish a fixed HVAC or water-heater dollar amount; the approved scope is determined after an assessment. HVAC replacement has additional homeowner and existing-equipment restrictions.
Confirm who submits the application and which documents are required before relying on an incentive. Start with our California HVAC rebates guide, then check the current program terms. Budget for the project separately from an unconfirmed rebate.
The estimate above is a starting point
The real number depends on your specific room geometry, existing electrical capacity, line set routing, and the selected equipment. Installation assessments are free, with a written estimate before work starts.
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When to consider a ductless mini-split
Consider a ductless heat pump when a home has no usable ductwork. We check where the lines and drains can run, then compare that work with adding ducts.
A room with its own temperature control. A bedroom or home office may need its own temperature control. We check that room’s load and how air will reach the occupied space before choosing a unit.
ADUs and garage conversions. Added living space needs its own load assessment. We check whether the existing system can serve it or whether a separate system makes more sense.
Rooms that heat and cool differently. Window exposure, insulation and use can vary across a home. Both ducted and ductless designs need to account for those differences. See our ductless mini-split service for installation details.
Considering a central ducted heat pump instead?
Existing ducts may make a central heat pump an option. We check their condition, distribution and the home’s load before comparing it with ductless equipment. The free central HVAC load calculator provides another preliminary estimate.
Mini-split vs central heat pump: which to pick
| Factor | Mini-split (ductless) | Central ducted heat pump |
|---|---|---|
| Existing ducts | Not required | Requires a suitable duct layout |
| Whole-home coverage | Head count and placement depend on the room layout | Air handler and ducts serve the connected spaces |
| Zone control | Per-head (granular) | Separate zones require a suitable control and duct design |
| Cost, single zone | Mitsubishi Electric: about $5,500-$9,000 for each room or zone, depending on the home | Compare the proposed duct layout and written estimate |
| Cost, whole home | Mitsubishi Electric: about $5,500-$9,000 per room or zone; exact written estimate after a free installation assessment | Written estimate after a free installation assessment |
| Aesthetics | Wall/ceiling heads visible in each room | Registers in the rooms; service access for the air handler |
| Consider for | ADUs, additions, no-duct homes, master-only | Whole-home replacements with existing ducts |
Going with central instead? Try the free central HVAC load calculator for ducted-system sizing. New to load math? Read how HVAC load estimation actually works.
ADU and garage conversion HVAC
For an ADU or converted garage, bring the construction plans to the assessment. We use them to size the system and plan its location and electrical work. Here is what we check:
- Outdoor location: confirm the selected model’s dimensions, clearances and service access.
- Routing: plan the refrigerant lines, drain and wiring around the building structure and manufacturer instructions.
- Independent system: your ADU tenant’s thermostat doesn’t affect your main house, and vice versa.
- ADU permit requirements: ask the local building department which plans, energy-code documents and inspections your project needs.
- Rebate eligibility: check the program’s current address, equipment and project requirements before budgeting for an incentive.
For a garage conversion, we check the insulation and room layout, wall and ceiling space, and the route to the outdoor unit. Then we can tell you whether ductless fits the project.
Plug-in and hardwired options
Before buying a plug-in heat pump, read its installation manual and heating-capacity data. Check that it can heat the room and that your circuit can supply it.
| Check | Document or assessment needed |
|---|---|
| Heating and cooling output | Exact model capacity data at the project’s design conditions |
| Electrical supply | Nameplate, installation instructions and an assessment of the existing circuit |
| Window or wall installation | Model dimensions, mounting instructions, clearances and property permission |
| Permits and inspections | Requirements confirmed with the local building department for the actual work |
Check any electrical work and property permission before buying. Our new ductless installations use Mitsubishi Electric. We can discuss the room and its electrical supply during the free installation assessment.
Model documentation and warranty checks
This comparison describes equipment you may already own or be researching. We repair and service other mini-split brands; our new ductless installations use Mitsubishi Electric.
| Brand | Cold-climate rating | Warranty | Consider for |
|---|---|---|---|
| Mitsubishi Hyper-Heat (M-Series) | Full capacity to 5°F, partial to -13°F | 12-year parts and compressor limited warranty for M-/P-Series; registration and ownership conditions apply (the HM, WR, HX and WX wall-mounted series top out at 10 years) | New installations selected for the room loads and approved equipment pairing |
| Daikin Aurora / Atmosphera | Check heating output for the exact model and outdoor temperature | Up to 12 years on equipment with registration where the model’s documented warranty applies. Our labor warranty is separate: 2 years standard, or 10 years with an active maintenance plan. | Existing single-zone systems; Andrew is factory-trained on Daikin |
| Existing equipment from other brands | Check the exact model’s heating-capacity data at the required temperature | Read its warranty document for registration, ownership, installation and coverage conditions | Diagnosis and repair of existing systems; confirm the model when booking |
How we recommend: For new ductless installations, we size a Mitsubishi Electric system to the rooms, outdoor design temperature and line-set layout. We continue to repair and service Daikin, Cooper & Hunter, Fujitsu, Bosch and other existing mini-splits.
Before approving a repair: we check the model, parts availability and supplier lead time. We give you the repair price and expected schedule after diagnosis and the supplier check.
As a Mitsubishi Electric Diamond Contractor, we register M-Series and P-Series installations within 90 days for the 12-year parts and compressor limited warranty (the HM, WR, HX and WX wall-mounted series top out at 10 years). This applies to a single-family home while the original owner lives there, and is not transferable. Our workmanship warranty is 2 years. Read the warranty terms and optional extended labor coverage. Daikin central AC and ducted heat pump installations remain available.
Bay Area furnace and water-heater emission rules
Checked September 28, 2026. The Air District has separate rules for furnaces and water heaters. These are standards for covered new equipment, not a requirement to remove a working appliance.
- Furnaces, Rule 9-4: ultra-low-NOx limits apply to covered units manufactured after January 1, 2024; the adopted zero-NOx standard applies to covered units manufactured after January 1, 2029.
- Furnace scope: the rule defines furnaces with heat input below 175,000 BTU/h. Its separate 65,000 BTU/h threshold concerns the cooling capacity of combination heating/cooling units, not furnace heat input. Mobile-home furnaces are excluded.
- Water heaters and boilers, Rule 9-6: the adopted zero-NOx dates are January 1, 2027 for covered small tank water heaters and January 1, 2031 for covered larger equipment, based on manufacture date. Equipment limits and exemptions apply.
Water-heater changes proposed in 2026 are still under consideration. Before choosing replacement equipment, check the adopted furnace rule, water-heater rule and current Air District updates, along with your local permit requirements.
Frequently asked questions
Does a second-floor bedroom install cost more? +
We check the line-set route, working height and drain during the free installation assessment. Those details affect the work. You get a written estimate before installation starts.
When does a mini-split make more sense than a central heat pump? +
Ductless can suit a home without usable ducts, an addition or a room that needs its own temperature control. If you have usable ducts, we also compare a central system. We measure the rooms and check where the units, lines and drains would go.
How is mini-split sizing different from central HVAC sizing? +
We size each indoor unit for its room and check that the manufacturer approves the indoor and outdoor units together. This calculator gives you a starting estimate. We measure the rooms and check the model data before choosing equipment.
What rebates are available for Bay Area mini-split installs in 2026? +
SVCE lists $2,000 for replacing gas heating, or $3,000 for income-qualified customers; electric-resistance replacements are $500 or $1,500 respectively. Reserve with SVCE before installation. WestLight lists $1,500 for a qualifying gas-heating replacement, with an additional $1,000 for eligible CARE/FERA customers; apply within 90 days after installation. Confirm your account, equipment and approved amount with the program. BayREN Home+ is closed. This calculator does not subtract rebates from its results.
Do mini-splits work in Bay Area winters? +
We compare your home's heating needs with the model's output at the local winter design temperature. For a Mitsubishi Electric Hyper-Heat system, we use the capacity data for the exact indoor and outdoor units.
What about the BAAQMD gas-ban rules I keep hearing about? +
Rule 9-4 covers certain gas furnaces; Rule 9-6 covers water heaters and boilers. The adopted furnace rule sets a zero-NOx standard for covered units manufactured after January 1, 2029. It does not require replacing a working furnace. Equipment scope, manufacture date and local permit requirements matter. Water-heater amendments were proposed in 2026 and are not yet adopted; check the Air District rule information before choosing equipment.
Ready to plan a real install?
We assess each zone on site, review equipment options and provide a written estimate after the free installation assessment:
- Ductless mini-split installation: single-zone or multi-zone systems
- Central heat pump installation: if existing ducts are workable
- Full HVAC installation: new construction or full replacement
- Maintenance plans: extend equipment life
Related reading: Heat pump vs mini-split · California HVAC rebates 2026 · What heat pump installation actually costs · What size heat pump do you need.
Ready for a real estimate?
Licensed Bay Area HVAC contractor (CSLB #1136642). We’ll walk through your calculator results, check your panel capacity, and put it in writing.
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