RADSIZER®: Our Cutting-Edge BTU Calculator

Planning on replacing your old radiator? Our brand new and improved BTU calculator, RADSIZER® is here to help make life a whole lot easier for you when choosing the right radiator for your home.

Now, you might be thinking: isn’t that what the BTU calculator does? What makes RADSIZER different?

RADSIZER is more than just a BTU Calculator - it goes beyond the simplicity of a BTU Calculator. Not only does it calculate heat loss and the ideal temperature of your room, but it uses an innovative algorithm by asking you a range of questions to provide a range of radiators that will sufficiently heat your home.

RADSIZER takes into consideration many factors including the type of property you have, the insulation of your home, roofing, how many windows you have, and your property age.

It also asks for your preferences when it comes to saving money, reducing carbon footprint, comfort, health concerns and your style and design preferences to offer you tailored recommendations for your needs - it doesn’t get better than that!

This useful information on RADSIZER ultimately helps you find an ideal radiator for your room’s energy requirement in Watts, saving you money with your heating bills and allowing you to consume less fuel in the long run by finding the correct radiator size for heating your room.

Start your journey to warming your home to perfection by discovering a range of stylish radiators with our advanced RADSIZER today!


Have you ever wondered how to work out the perfectly sized radiator for each specific room in your house? Well wonder no more, as UK Radiators’ BTU calculator does just that. Here are some frequently asked questions we receive from customers

What is a BTU?

BTU (British Thermal Unit) measures the appropriate amount of energy your radiators need to properly heat any room of your house. A specific radiator's heat output is measured in BTUs to work out the amount of energy required to heat one pound of water by one degree Fahrenheit. This gives you an indication of how many BTUs are required to heat a room, and in turn the specific radiator size that is required.

What is a BTU calculator?

BTU calculators are a great tool for working out how much energy you’ll need to efficiently heat up a room. Calculating the BTU for each room size is essential for maintaining energy efficiency in your home. It is important to carefully consider each radiator’s size to provide the appropriate heating for each room and cope with its insulation demands.

Fitting in inaccurately sized radiators to a room can cause insulating problems as it won’t meet the heating demands of the required space. That’s why it is important to use aour Radsizer BTU calculator and accurately work out the number of BTUs needed to heat each room in your home.

How to calculate BTUs?

When it comes to calculating the BTUs needed for a specific room, there are two main factors to keep in mind. Firstly, you need to decide at which temperature you would like to maintain each room. Pretty simple, right?

Secondly, you need to consider the heat loss from a room as this directly affects the constant level of temperature maintained in the space.

There are several factors that affect the heat loss of a room; its size, the number of windows and their insulating properties (single or double glazed), what is surrounding the room, and the number of internal and external walls. Taking all these factors into consideration can seem a bit complicated, but the general radiator sizing rule of thumb is, the bigger the size of the room, the more BTUs are required to maintain a consistent and comfortable temperature.

How to Calculate BTU for a room size

You can accurately measure the required BTUs for any room size by simply entering the required information into the our RADSIZER BTU calculator above, making sure the measurements given are as accurate and concise as possible.

The results will show the required total number of BTUs needed to keep that room size at a consistent temperature. You may need more than one fitted radiator to keep the constant and comfortable temperature required.

Here at UK Radiators we have a wide range of radiators to suit your heating needs and they come in all shapes and sizes to keep your room warmer for longer. Get in touch today to get a perfectly sized radiator for each room in your home, saving you energy costs and trouble!