What does an engine block heater cost to run?

Run the numbers on your own use

Change any of these and the figures update. The defaults are the typical case described above; your rate is the input that moves the answer most.

Why this is lower than the number you will see elsewhere

Almost every published answer to this question multiplies the rating on the label by the hours the appliance is switched on. For an engine block heater that gives 600 kWh a year, or $110.

Most block heaters have no thermostat at all. Plugged in overnight, they draw their full rating for every hour — which is why the timer matters so much.

The arithmetic, step by step

Nothing here is hidden, so you can check it or change it. Working in the order the formula runs:

1. 600 W — what it draws while it is actually drawing. This is the rating on the plate.
2. × 100% — the share of its in-service time it is really pulling that. Most block heaters have no thermostat at all. Plugged in overnight, they draw their full rating for every hour — which is why the timer matters so much.
   That gives 600 W averaged across the hours it is on.
3. × 10 hours a day × 100 days — Plugged in overnight through a cold-climate winter.
   600 × 10 × 100 ÷ 1,000 = 600 kWh a year.
4. × 18.34¢ — the US average residential rate for June 2026.
   600 kWh × 18.34¢ = $110 a year.

Change any assumption in the calculator above and every figure on this page moves with it. The two that matter most are your rate, which varies 4× across the country, and the hours — the duty cycle is a property of the appliance, but the hours are a property of you.

How sensitive is that number?

A single figure invites more confidence than it deserves. Here is the same appliance under assumptions either side of the default, so you can see how much of the answer is the appliance and how much is the guess about how you use it.

Everything else held at the default. The spread here is the honest error bar on the headline figure.

What it costs per hour, day and month

At 18.34¢ per kWh, the US residential average for June 2026.

The thing worth knowing

An engine block reaches its useful temperature in about three to four hours. Everything after that is heating the outdoors, and since most units have no thermostat there is nothing to stop them. A ten-hour overnight plug-in therefore wastes roughly two thirds of what it uses, and a five-dollar timer recovers all of it.

What it costs in your state

The appliance is the same everywhere; the rate is not. Running this engine block heater costs $316 a year in Hawaii and $79 in Nevada — a difference of 4×.

Cost of running one engine block heater for a year, by state. Residential average price, EIA June 2026.

Other EV charging costs

• EV charging (Level 1 wall socket)

  $687 a year

  The same 11,100 miles a year on a standard outlet, including about 15% charging loss.

• EV charging (Level 2 home)

  $649 a year

  11,100 miles a year at 3.5 miles per kWh on a 32 A charger, including about 10% charging loss.

• Golf cart charger

  $133 a year

  Charging a 48 V lead-acid pack after most days' use.

• E-scooter charger

  $14 a year

  Charging a mid-size commuter scooter most days in the riding season.

• E-bike charger

  $12 a year

  Charging a 500 Wh battery from low most days through the riding season.

• Battery trickle charger

  $6.93 a year

  Maintaining a seasonal vehicle’s battery through the off-season.

Questions

Source: U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A, June 2026. U.S. Government work, public domain.

How every figure on this page is computed · Where the data comes from