How to calculate the cost of landscape lighting

Our customers frequently ask us how much their power bill will increase after their new system is installed. Nowadays we’re only installing LED systems so our response is, “You will not even notice it.”

However, back when we installed incandescent systems the power requirements were much greater. While the number was relatively low compared to air conditioning units and the like, we would always provide cost estimates.

This article will show you how to calculate the cost of power for landscape lighting. If you don’t want to do the math we’ve included a handy calculator so you can quickly determine the cost for your system (or any other electrical component for that matter).

The Formula

(total-wattage ÷ 1000) x  hours-per-day-used x 365 x your-kwh-cost = Annual cost for your system.

The Math

Add the total wattage of your bulbs/fixtures.

Divide your total wattage by 1000 to covert to kilowatts.  Now you have your kilowatt per hour (kwh)  consumption.

Multiply your kilowatt per hour consumption by the number of hours per day your lights will be on. This gives your daily kilowatt consumption.

Next multiply your daily kilowatt consumption by 365 to get your annual kilowatt consumption.

Finally multiply your annual consumption by your cost for power (in the US the average is about $.11/kwh¹).

Sample Calculation

We installed a typical LED front-yard system this week so lets calculate the annual electrical cost for this customer.

The system has 11 3-watt fixtures and two 2-watt fixtures so that totals 37 watts.  Divide that number by 1000 and we see that her usage will be .037kwh. This customer will run her lights for an average of 8 hours per day so her daily kilowatt consumption will be .296 kilowatts. Her system runs every day so multiplying by 365 we get an annual usage of 108.04 kilowatts. She lives in Atlanta and the average kwh charge by her power provider is $.12/kwh. So multiply her annual usage by the rate and we see her annual cost will be $12.96.

The Calculator

If you are not into the math and just want a quick answer use our handy calculator below.

Tired of the math?

US Energy Generation

US Energy Generation. Click for details.

This article is intended to give you a general guideline for the power usage of various lighting options. There are many other considerations when determining the optimum fixtures for your environment. If you would like to go into more detail we are available for discussion.

We offer free consultation and design we’d love an opportunity to work with you. Our contact information is below or you may visit our FREE CONSULTATION page to schedule an appointment.

Call 770-521-2805
or email [email protected]


1. Electric Power Monthly, October 2014 ~ US Energy Information Administration.