Rointe towel rail and radiator size calculator

To help you calculate your electric heating size (like your electric radiator or towel rail), we’ve created a handy online size calculator to guide you on which product size to purchase. You’ll also find a range of tools, resources and information so you can calculate the necessary radiator elements and towel rail requirements correctly for your home, office or project.

Can we help?

Send us your details and let us advise you on the best Rointe electric heating solution to meet your needs.

How to calculate electric heating sizes for a room

The success of Rointe electric heating products is due to correctly calculating the size of each product needed. That's why we've developed the Rointe Thermal Coefficient (RTC) to help increase efficiency and savings.

Our unique method means we can provide an estimated radiator size calculator, along with towel rails, for our customers free of charge.

What is the BTU?

We use the BTU for each climate zone to calculate the Rointe Thermal Coefficient, which determines the element size of each radiator for your room.


A British Thermal Unit (BTU) is a measure of heat output from a radiator. This is the measurement used to figure out how much energy is needed to heat (and cool) a room based on its size.


Simply put; the higher the BTU, the higher the energy output will be. How effective that is though depends on the size of a room and what lies behind the walls, floor and roof. That’s where the Rointe Thermal Coefficient comes into effect.

Rointe Thermal Coefficient

The RTC calculates the number of heating elements needed for a property, based on its square metres and geographic climate.


By using this calculation we can determine the appropriate radiator or towel rail size for the most balanced consumption.

Rointe Thermal Coefficient calculation

When we use our radiator size calculator, we need to distinguish between m2 and m3:

· For ceilings with a height lower than 3 metres, we use the R.T.C. (m2).

· For ceilings with a height higher than 3 metres, we use the R.T.C. (m3).

Rointe climate map of Ireland showing mild, cold, very cold and extra cold areas

Calculation m2 – ceiling height less than 3 metres

Size reference table for D Series, Kyros and Sygma radiators in m2

Rointe heating radiator size calculator for ceiling heights up to 3m

Size reference table for Kyros and Sygma short radiators (reduced height) in m2

Rointe heating conservatory radiator size calculator for ceiling heights up to 3m

Calculation m3 – ceiling height more than 3 metres

Size reference table for D Series, Kyros and Sygma radiators in m3

Rointe heating radiator size calculator for ceiling heights over 3m

Size reference table for Kyros and Sygma short radiators (reduced height) in m3

Rointe heating conservatory radiator size calculator for ceiling heights over 3m

An official Technical Study should be conducted before any installation of a Rointe heating product is carried out. The calculations on our online tool and reference tables are estimates and should be regarded as such.

Parameters considered when sizing radiators and towel rails

In order to achieve maximum comfort and energy efficiency, several factors need to be considered to calculate the correct Rointe electric radiator or towel rail size.


Even though your heating installation could be a house, apartment, office, hotel or other property, it’s important you know and understand the parameters considered before sizing or purchasing a Rointe electric heating system.


The orientation of a room has an impact when calculating the radiator size. For example, south-facing homes have an advantage over other others since they have greater contact with sunlight and warmth.

Climate zone

The UK has a varied average temperature range. Depending on the area, the country is divided into 4 climate zones, therefore it's important to consider where the heating installation is located.


Insulation plays a key part in maintaining a stable temperature in your property and can increase energy savings. A more insulated room will be more efficient and require less energy to heat.


If more than 1 product is required, they should be distributed evenly e.g. a 21m2 room needs 18 elements, made of two 9 element radiators with equidistant space between them.

Build & furnishings

The type of room or property has an impact on efficiency since they have characteristics that make them more or less vulnerable to heat loss, e.g. attic or kitchen. Stairs and furniture also play a key part in sizing.

No matter the type of property (hotel, office, public building etc.), if you’re thinking of switching to our low consumption electric heating ranges, then get in touch.


We can recommend specific products to meet your demands, conduct on-site visits and provide our expert knowledge and opinion on the best solutions for energy efficient heating.


This service is free of charge and ensures a tailor-made, quality installation that’s designed just for you with the best possible efficiency.


Call our Sales & Projects department now on 01 553 0523 or send us your details using the contact form.

Ready to buy a Rointe heating system?

If you already know the products you need, you can browse our online store now.

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