• Get the best quotes, fast!
  • Over 5,000 engineers across the UK
  • Gas Safe registered engineers

Need a New Boiler?

What work do you require?

Or do you require a boiler repair?

Get THE Best Deal

by quickly comparing 3 FREE quotes

  • Next day installation
  • Quotes from local engineers
  • 1.9 million quotes in 10 years
  • Save up to £500 on installation

The smarter way to find approved heating engineers

Excellent 4.8 out of 5 Trustpilot

Stay Safe.
Always use a Gas Safe registered engineer

Gas Boiler Installation Calculator

Boiler Guide Team
By: Boiler Guide Team
Updated: 29th September 2023

Welcome to the Boiler Installation Calculator

We’ve built this free-to-use tool to help you get indicative costs of a new boiler installation. The calculations are based on a mid-range gas boiler and average installation costs – depending on your unique requirement.

We ask a range of questions in order to calculate a price tailored to your situation. Please remember that this is an indicative price and you will still need to get boiler quotes from an approved installer before any work is carried out.

Here’s the background on the questions we ask throughout the calculator…

Property type

This will impact both the size and type of boiler you need e.g. a Conventional boiler needs a large storage tank and hot water cylinder, so it's usually not suitable for smaller homes.

No of Bedrooms

This gives an indication of the size of the area to be heated. The more bedrooms you have, the higher the output needed.

No of Bathrooms

If you have more than one bathroom you may need a boiler with a hot water storage cylinder to cope with the higher hot water demand.

Current boiler

The price of installation will be affected by what's in place now; a like for like replacement will be cheaper than introducing an entirely new system.

What type of boiler do you require

The complexity of the installation will impact the price e.g. a Conventional system includes a storage tank and water cylinder as well as the boiler, whereas a Combi boiler is a single unit.

No of radiators

The more radiators the boiler needs to supply the more powerful it needs to be. If installing TRVs (Thermostatic Radiator Valves) on all radiators this will also increase the cost.

Average prices for a new gas boiler

We’ve put together the below tables showing the average price that our customers have been quoted based on their property type and number of bathrooms. These prices are all based on a combi boiler being replaced with a combi boiler and include the cost of a powerflush and magnetic filter.

Terraced House

Number of bathrooms Typical cost
1 £2,460
2 £2,650
3+ £3,000

Semi-detached House

Number of bathrooms Typical cost
1 £2,548
2 £2,770
3+ £3,300

Detached House

Number of bathrooms Typical cost
1 £2,682
2 £2,881
3+ £3,500

Flat/ Apartment

Number of bathrooms Typical cost
1 £2,376
2 £2,520


Number of bathrooms Typical cost
1 £2,690
2 £2,833

Do you require a Powerflush

It's highly recommended that an installer performs a Powerflush on your system before installing the new boiler to avoid the new system being contaminated by sludge and debris from the old. An engineer will connect a pump to your central heating system and push special chemicals through the pipes, boiler and radiators.

Do you require a Magnetic Filter

A Magnetic Filter is an optional component that attracts and collects metallic debris in the system, prevents blockages and can lengthen your boiler's life.

Looking for oil boiler prices?

We will soon be adding oil as a fuel type to the calculator very soon, but in the meantime please use our current service to get oil boiler quotes.

Boiler Guide Team

About the author

Boiler Guide Team

Boiler Guide has been home to a host of heating experts who have helped millions of UK homeowners searching for advice and guidance. If you’ve got heating questions, we’ll have the answers.

Need a new boiler?

Get FREE no-obligation quotes now!

Find local heating engineers

Find approved boiler engineers
in your area.

Begin your search by entering your postcode below.