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What The Patio Heater Cost Calculator Works Out
- Per evening: the heater's hourly cost multiplied by hours used. A 2kW electric infrared heater draws 2 kWh an hour, about 53p at the current Ofgem price cap rate (26.32p per kWh from October 2026); a 13kW gas mushroom burns roughly 0.95kg of propane an hour, about GBP 3.14 at GBP 3.30 per kg.
- Per month: the evening cost multiplied by evenings per month. Eight three-hour evenings cost GBP 12 to GBP 15 on electric and GBP 75 or more on gas, a five-fold gap that pub gardens absorbed knowingly and households usually discover on the second bottle refill.
- Warmer for less: fleece blankets, a windbreak and a table against the house wall cost nothing to run, and a 100W heated seat pad warms one person for about 3p an hour. Outdoor cold is mostly wind.
- Electricity unit rate (advanced): defaults to the current Ofgem price cap unit rate; change it for your own tariff or an off-peak rate. Gas users can edit the propane price per kg and the heater's burn rate, which varies with the setting and bottle pressure.
- Months of use and number of heaters (advanced): turn the monthly figure into an annual total and scale it for several heaters. Six months covers April to September; a hospitality-style setup with three or four heaters multiplies everything.
- Per hour and per year (advanced): the running cost per hour of use and the yearly total with the hours it covers.
- The other fuel for the same hours (advanced): what the alternative technology would cost for identical use, so gas owners see the electric bill and electric owners see the gas one.
- Propane bottles per year (advanced): kilograms burned divided by the standard 13kg patio bottle, with the refill price. A regular gas user gets through several bottles a season, each needing collection and exchange.
- Payback on switching to electric (advanced): the price of a new electric heater divided by the yearly saving over gas. At typical prices it pays back within a season of regular use. Never run a gas heater indoors or in a sided gazebo: carbon monoxide ignores canvas ventilation folklore.