1 Ton Per 400 Sq Ft Undersizes DFW Homes
That rule of thumb was written for milder climates. In Dallas-Fort Worth, summer means months of 100°F+ days, relentless sun, and heavy solar gain on roofs and west-facing windows. A unit sized by the national shortcut simply can't keep up.
An undersized AC short-cycles — it runs almost continuously trying to hit your setpoint, never quite gets there, wears out compressors early, and runs your electric bill sky-high. Oversizing is just as bad: a unit too big cools fast but never dehumidifies, leaving your home clammy. The right answer is neither — it's the actual load for your home.
The DFW Guide
For a typical 2,000–2,500 sq ft single-story home in the Dallas-Fort Worth Metroplex, expect roughly a 3.5–5 ton system. Multi-story homes, poor insulation, lots of west-facing glass, or a dark roof push that toward the top of the range. But no square-footage rule replaces an actual calculation.
Undersized (too small)
- •Runs constantly, never reaches setpoint
- •Short-cycles and wears out compressors early
- •Higher electric bills from endless runtime
- •Poor dehumidification — home feels warm and sticky
Oversized (too big)
- •Cools fast but never runs long enough to dehumidify
- •Clammy, humid indoor air
- •More wear from frequent on/off cycling
- •Higher upfront cost for capacity you don't need
The Correct Answer: a Manual J Load Calculation
A Manual J calculation is the ACCA industry-standard method for sizing HVAC equipment. It accounts for your home's square footage, ceiling height, insulation, windows, orientation, local climate data, and occupancy — the real heat load, not a guess.
Measure Square Footage
Total conditioned living space is the starting point — but never the whole story in Texas.
Account for Heat Load
Texas summer sun, ceiling height, insulation, and window exposure all add real cooling demand.
Run a Manual J Calculation
The ACCA Manual J calculation is the industry-standard way to size a system to your actual home.
Match Tonnage to the Load
A right-sized AC runs long enough to dehumidify and cool — without short-cycling and wearing out.
Book a Free Load Calc
Stop guessing on tonnage. Let Cowboy Air run a real Manual J calculation for your Dallas-Fort Worth home and tell you exactly what size AC you need — at no cost.