BTU Room Calculator

Estimate the AC or heater BTU size your room needs from its dimensions.

Length (ft):

Width (ft):

Ceiling height (ft):

Insulation:

Sun exposure:

How to use

Enter room dimensions and conditions, then click Calculate. Everything runs in your browser — nothing is uploaded or stored.

How many BTU for a 200 sq ft bedroom?

Roughly 5,000–6,000 BTU depending on insulation and sun.

What is a ton of cooling?

12,000 BTU per hour.

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Every tool runs 100% in your browser — no uploads, no signups. If a tool saved you time, consider supporting us with a small donation.