Splitsizer Heat-pump decision guidance
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Mini-split sizing for US homeowners

Size the room. Check rebates. Choose the right system.

Start with the decision in front of you: a BTU range for one room, incentives available where you live, or a system comparison for your installation plan. Whole-home work still needs a formal load calculation from a qualified installer.

Estimate BTU size Check rebates Estimate install cost Check an installer quote Compare systems
5
inputs that affect load
8
standard sizes checked
0
contact fields required
Northeast residential street typical of homes that need ductless cooling.
Sample calculator output

20,200-23,800 BTU · shop the 24k class

1,100 sq ft · mixed climate · average insulation · medium sun

The approach

A range first. A product later.

Square footage is the starting point, not the answer. Insulation, sun, climate, and ceiling height routinely move a room up or down one standard equipment size. A useful estimate accounts for all of them.

Square footage is the start

Climate band, insulation, sun exposure, and ceiling height all change the BTU number — sometimes by an entire size class. Skipping them produces a number that does not survive contact with a real room.

Standard sizes, not false precision

Mini-splits are sold in standard classes: 6k, 9k, 12k, 18k, 24k, 30k, 36k. The useful answer is which class the project lands in, not a decimal-precise BTU figure.

Single room is not whole home

One enclosed room is a different project from a multi-room replacement. Screen with a BTU range first; whole-home work still needs a Manual J load calculation from a qualified installer.

Popular sizings

Common rooms, sized.

400 sq ft small bedroom / office 500 sq ft bedroom / studio 600 sq ft master / large bedroom 800 sq ft large open room 1,000 sq ft open area 1,200 sq ft mid-home screen 1,500 sq ft 1-floor home 2,000 sq ft whole-home screen
Start here

Three checks before you buy.

A BTU number narrows the search. It does not settle code, rebates, electrical capacity, or final equipment design — those come next.

Before you sign
What does the quote document?

Paste the proposal for a private, on-device check of equipment details, load calculations, electrical scope, permits, commissioning, and warranties.

Check the proposal →
Sizing 101
Range first, model second

Use the calculator to avoid shopping blind, then compare equipment inside the recommended size band. Bigger is not automatically better.

Money check
Verify incentives late

Federal, state, utility, and local programs change. Check official rebate and tax-credit rules close to purchase, not at the start of research.

Start with the estimate

Five inputs. One useful range. Yours.

Square feet, climate, insulation, sun, ceiling. About a minute. No email needed.

Run the calculator