Reptile Electricity Cost Calculator: What Your Lamps and Heaters Cost

How the calculator works

Each device's daily energy is its rated watts, times the hours it is on, times the average share of that power it draws, divided by 1,000 to give kilowatt-hours (kWh). The calculator adds the devices, multiplies by 30.4 days for a month and 365 for a year, and multiplies the energy by your rate.

Step	Formula	Default example
Basking lamp	75 W x 12 h x 100% / 1,000	0.900 kWh a day
UVB lamp	24 W x 12 h x 100% / 1,000	0.288 kWh a day
Total per day	Sum of devices	1.188 kWh
Per month	1.188 kWh x 30.4 days	36.1 kWh
Cost per month	36.1 kWh x $0.183	$6.61
Cost per year	1.188 kWh x 365 x $0.183	$79.35

The defaults and where they come from

Input	Default	Why
Basking lamp watts	75 W	Arcadia's 75-watt PAR30 halogen flood is the lamp Arcadia calls its most popular halogen heating lamp, and the one in its Optimal Heating Pack.
Basking lamp hours	12 h	Arcadia advises grouping heat and light over the basking zone, so the lamp runs for the same day length as the UVB lamp (below).
Basking lamp power share	100%	The most the lamp can draw. A thermostat lowers it by an amount that depends on your room and enclosure, so we start at the ceiling; lower it if your thermostat shows the power it applies.
UVB lamp watts	24 W	The standard 22-inch T5 HO tube: Arcadia's 22-inch T5 lamps and Zoo Med's 22-inch ReptiSun T5 HO are both 24 watts.
UVB lamp hours	12 h	Zoo Med's UVB guidance refers to lamps used 10 to 12 hours a day; we use the upper end.
UVB power share	100%	Fluorescent UVB lamps are not dimmed or thermostat-controlled; Zoo Med says its ReptiSun lamps need line voltage and cannot be used with its thermostats.
Night heat	0 W	Set to zero unless your room gets colder than your species' night range. If it does, enter the heater's watts: Arcadia's Deep Heat Projector is 50 or 80 W, Zoo Med's ceramic emitters 60, 100 or 150 W.
Other devices	0 W	Misters, foggers, fans and plant lights vary too much for a default; enter the watts printed on the device or its adapter.
Electricity rate	18.3 cents/kWh	US average residential price for July 2026 (18.31 cents), EIA Electric Power Monthly, Table 5.6.A, released September 24, 2026. The next release is due October 23, 2026.

Worked examples

All figures at 18.3 cents per kWh. Device wattages are the makers' ratings; hours are what you would set on a timer. The power shares are the 100% ceiling unless stated.

Setup	kWh per day	Per month	Per year
Defaults: 75 W lamp and 24 W T5, 12 h each	1.188	$6.61	$79.35
Same, but the thermostat shows the lamp averaging 50% power	0.738	$4.11	$49.29
Desert setup: 75 W halogen, 39 W Arcadia T5 and 50 W deep heat projector, 12 h each	1.968	$10.95	$131.45
Small gecko setup: 35 W halogen and 8 W ShadeDweller for 12 h, plus a 16 W heat mat for 24 h	0.900	$5.01	$60.12

The second row shows why a proportional thermostat matters for running costs as well as safety: whatever share your lamp actually averages comes straight off its line in the bill.

Your electricity rate

Residential prices vary several-fold between states. The default setup above (1.188 kWh a day) costs:

July 2026 residential price by state, EIA Table 5.6.A

State	Cents per kWh	Default setup per month	Per year
Louisiana	12.72	$4.59	$55.16
US average	18.31	$6.61	$79.35
California	33.61	$12.14	$145.74
Hawaii	48.00	$17.34	$208.14

Use the rate on your own bill, including delivery charges if your utility bills them per kWh.

Ways to lower the bill without cutting corners

• Use a proportional thermostat. A dimming thermostat on a basking lamp, or pulse control on a mat or emitter, delivers only the power needed to hold the set point. See our best reptile thermostats.
• Choose the right wattage. Arcadia advises a lower-wattage lamp with a beam wide enough to cover the animal over a larger lamp dimmed hard, and says its 35-watt halogen can for most replace a 75-watt standard tungsten lamp. Our best reptile heat lamps guide covers sizes.
• Put lights on a timer. Hours are the other half of the formula; a timer keeps the photoperiod exact.
• Do not skimp on UVB. A 24-watt tube on for 12 hours costs about $1.60 a month at the US average rate. Replace it on schedule; see the best UVB lights for reptiles.

Never save money by running a heater without a thermostat or with a guard removed; our heating safety guide explains why. If you are also building a planted enclosure, our guide on how to set up a bioactive enclosure covers the layers and what they need.