Estimate what a professionally installed split system should cost for your home, before an installer ever quotes you. Answer five questions and get a realistic fitted price range — so when the quotes arrive, you know which ones are fair.
How to use this number: it's a benchmark, not a quote — real prices depend on the survey. Get three quotes and expect them to land inside or near this range. A quote far above it needs itemised justification; one far below it deserves suspicion (check F-Gas certification, what's excluded, and whether the vacuum-and-pressure test is included — see what a proper install involves).
The model starts from the typical UK fitted price for a single-room split system (£1,500–£2,200 for a standard installation including the unit, bracketry, pipework allowance, dedicated circuit and commissioning), then adds per-room costs for additional indoor units (£800–£1,300 each — cheaper than the first because the outdoor unit and electrics are shared), access and pipe-run complexity, consumer unit work where needed, and a regional uplift for London and the South East. It reflects the same market ranges as our full cost guide, where the assumptions are unpacked.
Two costs it deliberately leaves out: freeholder consent costs for flats (typically £500–£1,000+ in legal and surveyor fees — see the flats guide), because they're paid to your freeholder, not the installer; and running costs, which have their own calculator. And if you haven't confirmed what size system your rooms need yet, start with the sizing calculator — an installer quoting without sizing is guessing.