Mobile Home AC Unit Sizing Guide | Sizes That Fit

The right mobile home AC size depends on square footage and climate; most homes need 1.5–3.5 tons, and Energy Star’s county-based method gives the precise number.

An undersized unit runs nonstop in summer. An oversized one short-cycles, leaves the home clammy, and jacks up the electric bill. The right size fixes both — and the sizing method is more straightforward than most buyers expect.

This sizing guide walks you through the official calculation, the tonnage chart for common home sizes, and the compatibility checks that stop a correctly sized AC from failing. You need three things: the home’s conditioned square footage, the climate where it sits, and the maximum capacity listed on the manufactured home’s data plate.

The Sizing Method That Matches Your Home

The starting point is Energy Star’s official manufactured home cooling sizing guidelines — the document is written specifically for manufactured homes, not site-built houses. The process takes four steps:

• Find the county where the home is sited and look up its Sizing Group number on the Energy Star map.
• Measure the home’s conditioned floor area — every heated and cooled square foot, not the overall footprint. Don’t guess.
• Using the conditioned floor area and the Sizing Group, read the required cooling capacity in tons from the sizing table.
• If you’re replacing an existing unit, check the data plate and match the previous size as closely as possible if it worked correctly.

A fast cross-check before you open the table: roughly 20 BTU per square foot of conditioned space, which works out to about 1 ton per 500–600 square feet. Both are rule-of-thumb figures; the Energy Star table is the official answer.

AC Size by Square Footage

The chart below shows common sizes, their BTU output, and the approximate square footage they serve in a mobile home. The exact figure shifts with climate and insulation, so use these ranges as a starting point, not a verdict.

In practice, single-wide homes usually land around 1.0–2.0 tons, and double-wides typically run 1.25–4.0 tons. A 980 sq ft home, for example, starts at roughly 19,600 BTU — call it 1.5–2 tons.

Before You Buy: Data Plate, Coil, and Airflow

Floor area alone doesn’t finish the job for a manufactured home. The data plate and the existing ductwork can veto the size the chart suggests.

• Find the manufacturer’s maximum BTU rating under “Comfort Cooling” on the data plate, then divide by 12,000 to convert it to tons.
• The indoor coil and outdoor condenser tonnage must match. A mismatched pair is a common failure mode — the system short-cycles, cools poorly, and builds up humidity.
• Restricted airflow can make a correct size behave like an undersized one. Blocked registers and undersized ductwork are the usual culprits, so clear every register and confirm the ducts handle the airflow before committing.

Poor insulation, large window areas, and hotter climates can justify stepping up half a ton. Those are practical adjustments, though, not official sizing rules — and they cut both ways. A well-shaded, well-insulated home can often step down.

Why a Correctly Sized Unit Still Fails

Three mistakes account for most “it was sized right but never worked” stories: an unmatched indoor coil, restricted airflow, and ignoring the data plate’s limit. If the furnace has limits, the new AC can’t exceed them without a matching coil. Get those three right and the sizing table in this guide will serve you well.

Once the sizing math is done, the next step is picking a unit that suits a manufactured home’s setup — our tested roundup of the best mobile home AC units compares the models worth your money.