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What sized radiator do I need to heat my room?

When you're creating an energy efficient and effective heating system for your home, you'll need to think carefully about sizing your radiators to cope with the heating demands of each room. Incorrectly sized radiators can be inefficient at heating the space or won't keep your room at a comfortable temperature, so it's important to work out the number of BTUs you need to heat each room in your home.

What's a BTU?

BTU stands for British Thermal Unit and it's the accepted measurement of energy for heating systems. Your chosen radiators will have their heat output measured in BTUs, which is the amount of energy required to heat one pound of water by one degree Fahrenheit.

How can I work out how many BTUs my room needs?

There are two parts to this equation. The first is the temperature you wish to maintain in each room, which is straightforward. The second is the heat loss from a room, which affects the consistency of the temperature you can maintain.

The rate of heat loss depends on several different factors:

• The size of the room
• What's above and below the room
• How many windows there are in the room, what type they are and whether they're single or double glazed
• The number of internal and external walls

These calculations can be complex to make, but the general rule of thumb is, the bigger the room, the more BTUs it will take to heat it comfortably.

How can I accurately calculate the BTUs I need?

To accurately measure the BTUs a given room will take to heat, simply enter the required information into the calculater below, ensuring that your responses and measurements are as accurate as possible.

The resulting figure will give you the total number of BTUs required to heat your room at a constant and comfortable temperature. You may need more than one radiator or heated towel rail to achieve this level of heat output.

How do I choose radiators that match my BTU requirements?

At The Heating Boutique we have a huge range of designer radiators, column radiators and convector radiators designed to create a modern and efficient heating system that's correctly sized for your home. Available in a wide range of sizes, finishes and different orientations to suit every style of decor and space, our high-quality products will provide the performance you need with the aesthetics you desire.


BTU Calculator

Fill out the form below with the details of your room and let our BTU Caculator do the rest for you.

Height of room (m):
Width of room (m):
Length of room (m):
Window Area (m²):

Type of room:

What is below the room?

What is above the room?

Type of outside walls:

Type of windows:

Number of outside walls:

Watts Required:
BTU's Required:




We can help you to decide on the right radiators for your property, contact us for more information.