Tools
Mini-split tools
Every number on this site comes from a certified rating or a manufacturer document, and these tools are how you apply those numbers to your own house. Start with sizing — it is the decision everything else depends on, and getting it wrong is the most expensive common mistake in ductless.
A word on sizing specifically: bigger is not safer. An oversized system short-cycles, never reaches its rated efficiency, and dehumidifies poorly, so a room that is genuinely 9,000 BTU is worse served by a 12,000 BTU unit than by the right one. Our calculator asks about insulation, exposure and ceiling height rather than square footage alone, because those move the answer more than floor area does.
If you already know your capacity, the product finder and comparison tool work from the same certified data as the model pages. If you have a fault code on the display, the error-code diagnosis tool covers 961 codes across 25 brands.
Mini Split Sizing Calculator
Use when room dimensions, ZIP, and load factors are ready for a sizing range.
BTU Room Estimator
Use for a fast capacity class before running detailed sizing.
Mini Split Operating Cost Calculator
Use when SEER2, HSPF2, usage, and power cost assumptions are known.
Mini Split Payback Calculator
Use when comparing project cost against expected annual savings.
Mini Split Installation Cost Estimator
Use when planning equipment, labor, electrical, materials, and permits.
Mini Split Electrical Lookup
Use before scoping voltage, MCA, breaker, or fuse requirements.
Mini Split Error Code Diagnosis
Use when a displayed fault code needs urgency, safety, and next-step guidance.
Mini Split Replacement Finder
Use when an old nameplate model needs a documented current successor.
Mini Split Product Finder
Use when capacity, voltage, brand, efficiency, or low-ambient filters matter.
Mini Split Rebate Finder
Use when ZIP, utility, and incentive paperwork could affect product choice or installer scope.
Mini Split System Compare Tool
Use when narrowing two to four specific systems side by side.
How to use these tools together
A mini-split purchase goes wrong in predictable places: buying on square footage alone, oversizing "to be safe," or discovering at install time that the panel can't feed the unit. These tools follow the order a careful buyer actually works in, so each answer feeds the next.
- 1. Size the room first. Start with the sizing calculator (or the BTU estimator for a quick capacity class). Getting BTUs right is the single biggest decision - an oversized unit short-cycles, never dehumidifies, and runs less efficiently, while an undersized one never keeps up in a heat wave or a cold snap.
- 2. Replacing an old unit? Enter the nameplate model in the replacement finder before shopping. If there is a documented same-brand successor, start there; if not, use the sizing and finder tools below.
- 3. Shortlist real systems. Feed that capacity into the product finder and filter by voltage, efficiency, brand, and cold-climate heating to a handful of candidates.
- 4. Compare the finalists. Put two to four side by side in the compare tool to see where the specs actually differ, not just the marketing.
- 5. Check local rebates. Enter the project ZIP in the rebate finder before choosing a final model. Many incentive programs depend on ENERGY STAR certification, utility territory, contractor paperwork, or program-specific product lists.
- 6. Check what it costs to run. Use the operating-cost calculator and payback calculator to weigh a higher-efficiency unit against its price over the years you'll own it.
- 7. Confirm the electrical and install. Before you buy, run the electrical lookup for voltage, MCA, and breaker size, and the installation-cost estimator for the all-in project budget.
- 8. Keep it running. Once it's installed, the error-code diagnosis tool translates a flashing fault code into what's wrong and whether it's safe to keep running.
Every calculator uses published, source-backed assumptions rather than guesses, and values we can't verify are marked plainly instead of invented. Final electrical, breaker, and permit decisions always belong with a licensed electrician and your local code authority.