BTU Calculator

Find the perfect radiator to heat your room with our BTU calculator. Find the optimum number of BTUs required for your room and create that warm, cosy temperature.

What does BTU mean?

BTU stands for British Thermal Units and is a unit of measurement for energy. Example: 150 British Thermal Units is equal to the amount of energy used to raise the temperature of 150 pounds or 68 litres of water 1-degree Fahrenheit or 1.8-degrees Celsius. You will see BTU used when referring to the amount of heat output a radiator emits to increase the heat in a room. The higher the BTU number associated with a radiator, the more heat that radiator can output to warm the room.
You can calculate the BTU heat output needed for all rooms including lounge, hallways, bathroom, bedroom and kitchen with our BTU Calculator.

You can get a rough idea of heating needs based on just the dimensions of the room and walls but for more accurate results what you need to know is;

  • Room Dimensions Including ceiling height in metres or feet
  • Number of windows in the room
  • Window Size
  • Type of glazing (single or double usually)
  • Number of walls on the outside of the building
  • Outside wall material
  • What is above and below the room

Room Dimensions
Width* Height* Length*
Window Area X² (Calculate this by multiplying window height by window length)

Room Information

Type of room:

*

Where are you heating?

What is below the room?

*
Think about the flooring of your room, and whether there is another room below

What is above the room?

*
Where applicable, choose the amount of insulation

Select type of outside wall:

*
This helps us calculate how much heat the room might lose

Select type of window:

*
This also helps us determine the expected heat loss in the space

Select number of outside walls (Optional) :

RESET
CALCULATE
Your Requirements
BTU's Required
Watts Required
Disclaimer: *Please note – Our calculations are only estimated and are based on information you provide. Our heating calculator can only process the most common factors that affect heat loss and may not take into account all factors relating to your particular requirements. Any results provided by our heating calculator should not be considered 100% accurate, and we accept no liability for any errors resulting from the estimates given. Calculations based on Delta – T 50°C (Δ-T50°C).*