Multi-Zone Ductless Heat Pump BTU Sizer

Per-room cooling/heating loads, indoor head selection & outdoor combination-ratio check for mini-split systems Estimate
Zones OFF
Design OFF
Loads OFF
Heads OFF
Ratio OFF
Outdoor OFF

Climate & Design Conditions

1% cooling / 99% heating design temperatures. Cooling is sized against a 75°F indoor target, heating against 70°F; the deltas are the window the system must beat.
°F
°F

Zones (Rooms)

0 zones

Outdoor Unit

Pick the tier you intend to specify; the tool checks the sum of indoor head capacities against this outdoor capacity. Typical ductless guidance allows a 100–130% indoor/outdoor combination ratio (many brands 50–130%).

System Results

Estimate
Total cooling load
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Total heating load
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Recommended system
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Per-zone loads & indoor heads
Indoor / outdoor combination ratio
Block-load ESTIMATE using walls (external-area & sol-air corrected), ceiling/roof with attic allowance, window conduction + solar gain, infiltration (ACH) with latent credit, occupants and a small internal-gain term. Verify with a Manual J or ACCA load calc and the outdoor unit's published combination table before purchase — this does not replace a pro. Different from whole-building sizing: here each room is its own head, and the sum of heads must fall in the outdoor unit's allowed combination range.

Checks

Multi-Zone Ductless Heat Pump BTU Sizer · zones → design → loads → heads → ratio → outdoor · local only, nothing leaves this page