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Electric Radiator Wattage: What size do i need for my room?

When it comes to choosing the right electric radiator wattage, it’s important to select the right size for your room. A radiator that is too small won’t provide enough heat, while one that is too big will waste energy and money.

In this blog post, we’ll discuss how to determine the appropriate size for your room and what other factors to consider.

What size do I need for my room?

At ElectriCast, we recommend the following electric radiator wattage based on room size:

  • 300w Radiator: suitable for rooms no larger than 3m x 3m with standard ceiling heights
  • 600w Radiator: suitable for rooms 4m x 6m with standard ceiling heights
  • 900w Radiator: suitable for rooms 5m x 7m with standard ceiling heights

These recommendations are based on average room sizes and ceiling heights. However, it’s important to accurately measure your room and take other factors into account when selecting the appropriate wattage.

For example, if your room has high ceilings or poor insulation, you may need a larger radiator to compensate. Alternatively, if your room has excellent insulation or is south-facing, you may be able to get away with a smaller radiator.

Other things to consider

In addition to the size of your room, there are other factors to consider when choosing the right size of electric radiator.

Type of insulation: A poorly insulated room may require a larger electric radiator wattage to provide sufficient warmth. Conversely, a well-insulated room may need a smaller radiator.

Ceiling height: If your room has high ceilings, you may need a larger electric radiator wattage to compensate for the extra space. In contrast, a room with low ceilings may require a smaller electric radiator wattage.

Windows: If your room has a lot of windows or large windows, you may need a larger radiator to compensate for heat loss.

Other heating sources: Rooms with additional heating sources such as underfloor heating or a fireplace may require a smaller electric radiator wattage. However, a room without any heating sources may need a larger electric radiator.

Tips for maximising the efficiency of your electric radiator

Regardless of the electric radiator wattage you choose, several steps can help maximize your radiator’s efficiency:

  • Use a thermostat: A thermostat can help you control the temperature of your room and prevent your radiator from wasting energy.
  • Install your radiator in the right place: Radiators work best when they’re installed on an inside wall, away from windows and doors.
  • Use radiator reflector panels: Radiator reflector panels can help to reflect heat back into the room, improving the efficiency of your radiator.


Choosing the appropriate electric radiator wattage is crucial to ensure your comfort and minimize energy costs. By accurately measuring your room and considering other factors, you can select the appropriate electric radiator wattage for your needs. Remember to consider insulation, ceiling height, and other heating sources, and take steps to maximize your electric radiator’s efficiency.

If you have any questions or need personalized recommendations, don’t hesitate to reach out to us for a free quotation or view our range of Electric Cast Iron Radiators on our online shop.