Calculate the right boiler size (kW) for your home based on radiators and bathrooms.
Recommended Size
24 kW
Range: 20-28 kW
Heating Need
15 kW
Hot Water Need
24 kW
Est. Install Cost
£2,500
An undersized boiler will struggle to heat your home, while an oversized one wastes energy. The right size depends on your radiators, bathrooms, and hot water needs.
Understanding your home energy usage is the first step towards reducing your bills. You may also find our Gas Heating BTU Calculator useful for related calculations.
For a broader view of your finances, try the Energy Bill Calculator or the Percentage Calculator. All of our calculators are free to use and updated for the 2026/27 tax year where applicable.
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