RVs and campers have thin walls, minimal insulation, and large window area relative to floor space. Calculators apply a higher BTU factor than a stick-built room of the same size.
A 200 sq ft living area in a travel trailer often calculates 7,000–9,000 BTU — buy 9,000 BTU minimum. Full-timing in Arizona or Florida commonly uses 12,000 BTU for 250+ sq ft.
Sizing by RV type
Roof AC replacement projects sometimes downsized incorrectly — mini-splits are more efficient but still need honest load math, not roof-unit BTU copied blindly.
Class B van: 100–150 sq ft cooled — 9,000 BTU typical
Travel trailer 25–30 ft: 150–250 sq ft — 9,000–12,000 BTU
Fifth-wheel or skoolie 30–40 ft: 250–350 sq ft — 12,000 BTU common
Slide-outs add area and leak points — include them in dimensions
Power and generator planning
9,000 BTU inverter mini-splits often draw 800–1,200W running on 110V. Startup surge matters for inverter generators. Shore power at 30A service is usually sufficient for one head.
Verify amperage on the label before boondocking — these are rough planning numbers, not electrical engineering sign-off.
Frequently asked questions
What size mini-split for a 30 ft travel trailer?
Most 30 ft trailers have 200–250 sq ft of cooled living space. Expect 9,000–12,000 BTU at RV insulation factors. Use the RV calculator with your exact interior dimensions.
Is 12,000 BTU too big for a small RV?
Calculated load may be lower, but inverter units modulate down. Undersizing on hot days is worse than slight oversizing with an inverter in RV applications.
Does a mini-split replace my roof AC BTU rating one-to-one?
Not always — roof units are often oversized and inefficient. Size the mini-split from room load, not the old rooftop sticker BTU.
HVAC Calculators provides estimates for planning only — not professional HVAC engineering or installation advice. Verify sizing with a licensed contractor before purchasing equipment. Read disclaimer