Mini-split sizing for US homeowners

Find a practical BTU range
for your actual space.

Answer five questions and get an approximate mini-split or heat-pump size in BTU per hour. Whole-home and cold-climate projects still need a formal load calculation from a qualified installer — the result will say so when that applies.

Size my system Browse sizing guides See how the sizing works

inputs that affect load

standard sizes checked

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.

Run a custom sizing →

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 buy

DIY or installer?

Small single-zone kits are the easiest to compare online. Whole-home and multi-zone projects need load calculations, electrical checks, permits, and local code review.

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

Find a practical BTU range for your actual space.