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Flame & Flagstone

Running cost

What a patio heater costs to run

Two formulas, two published prices, and every figure on this page derived from them. Substitute your own rate and the whole page recalculates in your head.

By Scooter M.

Published September 1, 2026

Last reviewed September 1, 2026

A glowing outdoor lamp against a dark evening sky

A 1,500 W electric patio heater costs about 28 cents an hour at the June 2026 U.S. average residential rate of 18.34 cents per kWh. A 48,000 BTU propane tower costs about $1.40 an hour at $2.674 per gallon. Four hours a night for a month is roughly $33 electric and $168 propane.

The two formulas

Almost nobody publishes these, which is odd, because they are the whole answer and they fit in two lines.

Electric

Cost per hour = watts / 1000 x your rate per kWh. A 1,500 W heater at 18.34 cents: 1.5 x 0.1834 = $0.275 per hour.

Propane

Cost per hour = rated BTU/h / 91,420 x your price per gallon. A 48,000 BTU heater at $2.674: 48,000 / 91,420 x 2.674 = $1.40 per hour. The 91,420 is the energy content of a gallon of propane at higher heating value, which is the same basis appliance ratings use.

The prices every cost figure on this site uses

Your rates are not these rates. Every table on this site is the arithmetic, not the verdict — put your own number in and the answer moves.

The tables

Electric, per hour

Rated powerPer hour4-hour eveningPer month, 4 h a night
750 W$0.14$0.55$16.51
900 W$0.17$0.66$19.81
1,200 W$0.22$0.88$26.41
1,500 W$0.28$1.10$33.01
2,000 W$0.37$1.47$44.02
3,000 W$0.55$2.20$66.02

At 18.34 cents per kWh (June 2026 U.S. residential average). Substitute your own rate: it is on your bill, and the arithmetic is watts ÷ 1000 x hours x rate.

Propane, per hour

Rated inputPer hour4-hour eveningPer month, 4 h a night
11,000 BTU/h$0.32$1.29$38.61
40,000 BTU/h$1.17$4.68$140.40
46,000 BTU/h$1.35$5.38$161.46
48,000 BTU/h$1.40$5.62$168.48
50,000 BTU/h$1.46$5.85$175.50

At $2.674 per gallon (week ending March 30, 2026 U.S. residential average) and 91,420 BTU per gallon. Exchange-cage cylinders cost materially more per gallon than a bulk refill, so treat this as the floor.

Reading these honestly

The obvious read is that electric is five times cheaper. That is true per hour and misleading as a comparison, because the two units are not doing the same job. The propane tower costs five times as much because it produces about ten times as much heat.

Normalize to cost per thousand BTU and it inverts: propane is about 2.9 cents per thousand BTU and electricity about 5.5 cents. Propane is the cheaper fuel. Electric is the cheaper evening, because on most patios that need heating you did not require 48,000 BTU in the first place.

Electric (1,500 W)Propane (48,000 BTU)
Output5,118 BTU/h48,000 BTU/h
Cost per hour$0.28$1.40
Cost per 1,000 BTUAbout 5.5 centsAbout 2.9 cents
A 4-hour evening$1.10$5.61
A month, 4 h a night$33.01$168.34
A season, 5 months$165.06$841.72

At 18.34 cents per kWh and $2.674 per gallon. A season here means five months at four hours a night, which is heavier use than most patios see.

Three things that make the real bill differ

  1. Exchange cylinders cost more than bulk propane. The EIA price above is for delivered residential propane. Swap-cage cylinders outside a supermarket cost considerably more per gallon, and are commonly filled to 15 lb rather than 20. If that is how you buy fuel, the propane column is optimistic.
  2. Your electricity rate is not the national average. State residential rates vary by more than a factor of two. Take the total from your bill, divide by the kilowatt-hours, and use that — the delivery charges are part of what you pay.
  3. Nobody runs a heater at full output all evening. Almost every unit here has a lower setting, and on a covered patio the lower setting is usually enough. A 1,500 W heater on 900 W costs about 17 cents an hour instead of 28.

The cheapest change is not a heater

A last point that the arithmetic makes and the category rarely does. Running cost scales with output, and output scales with the heat the patio needs — so the cheapest way to cut a heating bill is to need less heat.

On our sizing model, moving a patio from exposed to sheltered cuts the requirement by about 36 percent. A run of windbreak panels is a one-time cost that reduces every future hour, which no choice of heater does. And if the space can be covered, the reduction is about a third again.

Once you have done both, the cheapest to run picks are the units that come out best on the remaining requirement.

Common questions

Do patio heaters use a lot of electricity?

A 1,500 W patio heater uses about the same as a hair dryer and costs roughly 28 cents an hour at the June 2026 U.S. average residential rate. Four hours a night for a month is about $33. That is not a lot, but it is also not much heat — 1,500 W is only 5,118 BTU/h.

How much does it cost to run an electric patio heater?

Watts divided by 1,000, times hours, times your rate per kWh. At 18.34 cents, a 1,500 W unit is 27.5 cents an hour, a 4-hour evening is $1.10, and a month at 4 hours a night is about $33. On the 900 W setting it is roughly 17 cents an hour.

Are electric patio heaters expensive to run?

No, in absolute terms. They cost less per hour than propane because they produce far less heat. Per unit of heat delivered, electricity is actually the more expensive fuel — about 5.5 cents per thousand BTU against propane's 2.9.

How much does a 2kW patio heater cost to run?

About 37 cents an hour at 18.34 cents per kWh: 2 x 0.1834. Note that 2 kW exceeds the 1,440 W continuous limit of a standard 15-amp U.S. circuit, so a 2 kW unit needs a 20-amp circuit or a dedicated supply.

What is the cheapest patio heater to run?

Per hour, an electric infrared heater on its lower setting — about 17 cents at 900 W. Per unit of heat, propane. The cheapest change of all is a windbreak, which cuts the heat you need by more than any heater upgrade does.

Sources

Every figure on this page either comes from one of these sources or is computed on the page from a figure that does. If you think one of them is wrong, tell us — we publish corrections.

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