Free · Everyday · Home & Building

BTU Calculator

Estimate room heating capacity from floor area, ceiling height, temperature rise, and insulation quality.

  • Checked formula
  • Private in your browser
  • No signup
Calculator inputs

Enter your values

Result

Your calculation

Estimated heating capacity
72,000 BTU/h
Equivalent
21.1 kW
Room volume
2,400 ft³

A proper HVAC load calculation also accounts for climate, windows, air leakage, orientation, and occupancy.

How to use this calculator

  1. Enter the values and choose the units that match your situation.
  2. Calculate to see the primary answer and useful conversions.
  3. Review the assumptions before using the result for a project or decision.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.