BTU Calculator

By CalculatorInn Team · Updated: 2026-03-22 · Free & accurate · Instant results

Calculate the BTU capacity needed for heating or cooling a room based on square footage and environmental factors.

Interactive BTU Calculator

JavaScript is required for the interactive calculator. Enable JavaScript to use this tool.

How to Use This Calculator

Step-by-Step Instructions

  1. Enter your room size (sq ft)
  2. Enter your ceiling height (feet)
  3. Enter your sun exposure
  4. Enter your shaded
  5. Enter your average
  6. Enter your sunny
  7. Enter your number of occupants
  8. Enter your recommended btus
  9. Enter your ac tonnage
  10. Enter your room size
  11. Enter your suggested unit
  12. Results appear instantly — no button needed

Formula

Mathematical Formula

BTU = Square Footage × 20, adjusted for ceiling height, sun, and occupants

How It Works

BTU = Square Footage × 20, adjusted for ceiling height, sun, and occupants

Frequently Asked Questions

How does this work?

Enter your values in the fields above and the calculator will compute results instantly using the formula shown.

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