Patio Heater Running Cost Calculator

This patio heater running cost calculator works out what an electric or bottled gas patio heater costs per evening and per year. For an electric heater, enter its power, hours of use and your unit rate. For a gas heater, enter its heat output, the energy in each kg of gas, the bottle size and your refill price. It shows the gas used, how long a bottle lasts and the cost.

Quick answer: An electric patio heater costs its power in kW times the hours it runs times your unit rate. A 2 kW heater used for 3 hours uses 6 kWh, about £1.58 an evening at 26.32p, or £63.17 over 40 evenings. A gas heater’s cost depends on the gas it burns and the price you pay for refills.

How Is Patio Heater Running Cost Calculated?

For both types, start with the energy used: the heater’s kW times the hours it runs gives the kWh per evening.

For an electric heater, multiply the kWh by your unit rate. For a gas heater, divide the kWh by the energy in each kg of gas to get the kg burned, then multiply by the price per kg, which is the refill price divided by the bottle size. The default of 13.8 kWh per kg is an example for propane, so check the figure your gas supplier gives. The calculator also shows how many hours one bottle lasts at full output.

Gas heater ratings are usually the heat output at full power. Many gas patio heaters have a lower setting, which burns less gas, so use the setting you normally use if you know its output.

How Do You Use the Patio Heater Calculator?

1. Choose an electric or bottled gas heater.
2. Enter the heater power or heat output in kW.
3. Enter the hours per evening and evenings per year.
4. For gas, enter the energy per kg, bottle size and refill price.
5. For electric, choose a price preset or enter your unit rate.

How Much Does an Electric Patio Heater Cost to Run?

At 26.32p per kWh, an electric patio heater costs about 26p an hour for every kW of power.

The 26.32p unit rate is the Ofgem price cap average for October to December 2026. You can check the latest figure on the Ofgem energy price cap page.

Electric or Gas Patio Heater?

Electric infrared heaters warm people and surfaces directly, which suits covered patios and smaller spaces. Gas heaters often give out more heat and can stand anywhere, with no cable.

Gas heaters usually have a much higher heat output than electric ones, so they burn more energy each hour even if the gas is cheaper per kWh. Bottled gas is also usually more expensive per kWh than mains gas. The best way to compare is to enter both heaters in the calculator with your own prices. If you are heating a greenhouse rather than a patio, the greenhouse heater running cost calculator is set up for nights rather than evenings.

Worked Example: An 8 kW Gas Heater

Example: a household uses an 8 kW gas patio heater for 2 hours on 30 evenings a year, with 13 kg bottles at an example refill price of £30, and 13.8 kWh per kg.

• Energy per evening: 8 kW x 2 h = 16 kWh
• Gas per evening: 16 / 13.8 = 1.16 kg
• Gas per year: 1.16 kg x 30 = 34.8 kg, about 2.7 bottles
• Cost: about £2.68 an evening, or £80.27 a year

One 13 kg bottle lasts about 22 hours at full output in this example. A 2 kW electric heater used for the same 60 hours would cost about £31.58 at 26.32p, though it would give out much less heat.

Tips for Cheaper Patio Heating

You can stay warm outside for less with a few simple changes.

• Use a lower setting once everyone is warm.
• Shelter the seating area from wind, as heat blows away quickly.
• Point infrared heaters at where people sit.
• Turn the heater off when you go inside.
• Add blankets or outdoor throws for cooler evenings.

Gas patio heaters must only be used outdoors in a well ventilated area. Never use them in a tent, garage, conservatory or any enclosed space.

Patio Heater Running Cost FAQs

Checked October 2026. Source: Ofgem energy price cap. Gas energy per kg and refill prices are examples; use your supplier’s figures.