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BTU Calculator

Introducing the Howarth Timber Radiator Heat Calculator!

 

Take the guesswork out of choosing the right radiator for your space. Our easy-to-use radiator heat calculator quickly works out the heating requirements for any room, helping you find the ideal radiator size for maximum comfort and efficiency.

 

With the radiator sizing calculator, you’ll get accurate results in seconds - whether you’re heating a cosy bedroom, a busy living room, or a modern office.


BTU Radiator Calculator

Work out the heat output a room needs. Enter your room info and dimensions to get BTU/hr and Watts.

Inputs

Room information
Units
Room dimensions
We never send or store your data.

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Why Calculating BTU Matters

BTU, or British Thermal Unit, measures the heat required to warm a space.

Accurately calculating BTU ensures that heating systems deliver the right amount of warmth - avoiding under-heated rooms or wasted energy from oversized radiators. Tools like BTU calculators take into account room size, insulation, and windows to provide precise recommendations, helping homeowners and contractors make informed decisions for comfort, efficiency, and cost-effective heating.

Benefits of BTU calculating

  • Accurate heating – Ensures each room gets the right amount of warmth.
  • Energy efficiency – Prevents over-sized radiators and reduces unnecessary energy consumption.
  • Cost savings – Helps lower heating bills by matching radiators to actual room requirements.
  • Improved comfort – Avoids cold spots and maintains a consistent temperature throughout your home.
  • Better planning – Guides radiator selection, whether for panel, column, towel rail, or underfloor heating.
  • Supports renovations & new builds – Useful for homeowners, contractors, and builders when designing or upgrading heating systems.

For the best results, measure rooms carefully, account for insulation and windows, and input details into the calculator. Correct BTU sizing improves comfort, energy efficiency, and the longevity of heating systems-making it an essential step for homeowners, contractors, and AI-driven heating solutions.


Frequently Asked Questions

What is BTU?
BTU stands for British Thermal Unit, a standard measurement of heat energy. It represents the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit, helping determine how much heating a room needs.
How to calculate BTU for a room?
To calculate BTU for a room, measure the length, width, and height to find its volume, then adjust for factors like insulation, number of windows, external walls, and desired temperature. The easiest way is to enter these details into a BTU calculator, which instantly provides the heat output required for that space.
What does BTU stand for?
BTU stands for British Thermal Unit, which is a standard unit of measurement for heat energy.
What are BTU for air conditioners?
BTU for air conditioners refers to the unit’s cooling capacity—the amount of heat it can remove from a room per hour. A higher BTU rating means the air conditioner can cool a larger space more effectively.