What does a reptile heat lamp 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 a reptile heat lamp that gives 438 kWh a year, or $80.

Thermostat-controlled in any properly set-up enclosure, cycling to hold the basking temperature against the room.

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. 100 W — what it draws while it is actually drawing. This is the rating on the plate.
2. × 65% — the share of its in-service time it is really pulling that. Thermostat-controlled in any properly set-up enclosure, cycling to hold the basking temperature against the room.
   That gives 65 W averaged across the hours it is on.
3. × 12 hours a day × 365 days — A single basking lamp on a thermostat, plus a night-time heat source.
   65 × 12 × 365 ÷ 1,000 = 285 kWh a year.
4. × 18.34¢ — the US average residential rate for June 2026.
   285 kWh × 18.34¢ = $52 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

Like an aquarium heater, the duty cycle is set by the gap between the enclosure temperature and the room, so the same setup costs substantially more in a cold room than a warm one. Unlike most household loads it runs every day of the year, including summer, which makes a modest wattage into a real annual figure.

What it costs in your state

The appliance is the same everywhere; the rate is not. Running this reptile heat lamp costs $150 a year in Hawaii and $37 in Nevada — a difference of 4×.

Cost of running one reptile heat lamp for a year, by state. Residential average price, EIA June 2026.

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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