"Tonnage" is the most important number when buying an AC, and it's also the most commonly guessed-at wrong. Get it wrong in either direction and you'll pay for it — literally.
📏 Find Your Room on the Scale
Roughly 100-120 sq ft per ton, for a standard room with no unusual heat load:
Small bedroom
Medium bedroom
Living room
Large hall
Treat this as a starting point, not a precise formula — the checklist below shifts it up or down.
✅ Run Through This Checklist
Answer honestly for your room — each "yes" nudges you toward the next size up:
🚫 Two Ways to Get This Wrong
Too small — it runs flat-out constantly, never quite reaching your set temperature, wearing the compressor down faster while using more electricity than a right-sized unit.
Too big — the surprising one. It blasts the room cold fast, shuts off before removing humidity, then restarts minutes later. Feels cold but clammy, and that constant on-off cycling stresses the compressor more than steady running.