Landscape Lighting Calculator: Transformer, Wattage,

Minimum Wire Gauge, Voltage Loss over Distance!


All in one app: a collection of electrical calculators and tutorials that assist architectural and landscape lighting installers in creating an efficient lighting system at lower installation costs while increasing long-term safety. The calculators are customized specifically for 12V – 24V low voltage electrical systems that are commonly used for LED and halogen outdoor lighting (with a focus on 15V for LED). They are also extremely effective at troubleshooting installation issues!

Used by landscape lighting professionals worldwide for over two years!


Traditional electrician’s calculators require complex data, such as: resistance of wire, number of parallel connectors in the wire, ambient temperature along the length of wire etc. The Landscape Lighting Toolkit simplifies this for you by pre-calculating some data and removing other data that isn’t necessary for low voltage lighting installations. The result is this set of four handy calculators that require only a few data fields each, some of which are even pre-filled if you are using LED luminaires.

The Landscape Lighting Toolkit App includes:

Calculator: Minimum Wire Gauge

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Calculate the Minimum Wire Gauge needed for a run based on: VA or W, Length of Run, and Voltage. If using LEDs, we recommend using the 15VAC voltage tap. This will give you the most efficient landscape lighting system, as the higher voltage results in less loss due to wire length. We also provide a result with a wire gauge calculation based on a 10% higher load on the run. What this means is that the calculator returns a wire gauge that is capable of handling 10% more wattage than what was entered. This will give you some flexibility if you need to add 1 or 2 luminaires in the future (or change the wattage of the existing luminaires).

Calculator: Minimum Transformer Size:

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This calculator will help you determine the Minimum Size of the Transformer that you need for your landscape lighting system. To use this calculator, enter all the fields (VA or W, Length of Run, Voltage Tap, and Wire Gauge) and click Calculate. Repeat this for each run you would like to use on the transformer, the calculator will save each run as you enter it and keep a running total. The calculator will give you total VA or W and the minimum transformer size that should be used. This calculator will also verify for each run if the wire gauge and length of run you selected is capable of handling the VA or W entered. The calculator will notify you if there is a potential problem with your selection. If you made a mistake or would like to begin calculating a different system click the Reset button and this will clear all the runs that have been entered.

Calculator: Maximum Available VA or W:

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This calculator will help in determining the Maximum VA or W you can put on a given Gauge Wire, Voltage Tap, and Length of Run. This calculator is helpful if you already have a certain gauge wire and want to know how many lights can be used on that wire. Simply enter the distance you would like to run, the voltage used, and select the wire gauge from the drop down menu, and the calculator will tell you the absolute maximum VA or W you can use on that wire. We recommend following the Suggested VA or W, which gives a 10% lower number to ensure a problem free installation.

Calculator: Maximum Distance:

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This calculator will help you determine how far you can go with a given Wire Gauge, Voltage Tap, and VA or W. This formula is also helpful if you already have a certain gauge wire and want to know how far you can go with a given VA or W and voltage. For example if I have 12AWG wire and I want to know how far away I can go with 5) 10watt LEDs (50watts total) on the 15VAC tap, I plug in these values and get 377 feet. This answer is the absolute maximum. Again, the calculator will supply a Suggested Maximum Distance reduced by 10% for an optimal system.

Tutorial: Create an Efficient Lighting Layout

This tutorial is a step by step guide to creating an organized lighting plan, including: where to locate the transformer, how to group lights for efficiency, and tips on how to future proof your landscape lighting system.

Tutorial: Wiring and Connections

In this tutorial you will learn wiring and connection basics, how to look up National Electrical Code installation requirements, and where to get more detailed information if you are curious.

Tutorial: VA vs W (Volt-Amperes vs Watts)

Learn the difference between VA and W, and how to use them in the calculators.