Add every room, and we'll sum the loads. US mode recommends a central system size (or zoning above 5 tons). India mode recommends a per-room split AC plan — the way Indian homes actually buy. Share your plan with a link, no account needed.
Climate and tonnage snapping follow the US/India switch in the header. The share link encodes your rooms in the URL itself — nothing is uploaded.
| Total cooling load | — |
| Rooms | — |
A whole-house estimate is only as good as the rooms you feed it. Four things to get right:
| Whole-house total | Recommended setup |
|---|---|
| Up to 5 tons | A single central system — check the duct airflow (CFM) figure below |
| Above 5 tons | A zoned or dual-system setup, split across floors |
| India mode | A per-room split plan — Indian homes cool room by room |
Each room is sized on its own load, then the rooms are summed:
Switch with the US/India toggle in the header — the climate options and sizing rules change with it.
Not quite. Rooms rarely peak at the same moment, so a central system is sized to the simultaneous (diversified) load, which is usually a bit less than the raw sum. This tool totals room loads as a safe planning ceiling; a contractor's Manual J applies diversity factors. In India you don't diversify — each room gets its own split, so the per-room plan is the answer.
Above ~5 tons, or whenever the home spans two floors, two right-sized systems (or one system with zoned dampers) usually beat a single oversized unit — heat rises, so one big system leaves the upstairs warm while short-cycling downstairs. The FAQ covers the one-vs-two decision in detail.
Every room a central system actually conditions — including ones you're tempted to skip, since the ducts cool the whole envelope regardless. Skip unconditioned garages, unfinished attics and crawlspaces unless you plan to cool them. Add appliance heat for kitchens.
A 3-ton system needs roughly 1,200 CFM of airflow; older or undersized ducts that can't move it will choke a new condenser, cutting capacity and efficiency. Verify the CFM figure the calculator shows against your existing returns and supplies before buying a bigger unit.
per-room loads use ACCA Manual J factors (ANSI/ACCA 2); US code requires a full Manual J before equipment selection — ACCA. See our full methodology.