# Selecting the Right Transformer for Your Lighting

You will need to know the total number of lights and their wattages

If all your light wattages are the same, you simply multiply the wattage by the number of lights and multiply by 110% for power fluctuations.

Minimum Transformer Size Needed =  Light Wattage x Number of Lights x 110%

Example:  I have (5) 3-watt lights (shown above) that I plan to use, and I need a transformer.

Solution:  Use the formula above to solve:

Minimum Transformer Size Needed = 3 watts x 5 lights x 110% = 16.5 watts.

I will need at least a 16.5-watt transformer to run these lights.  I would need to size up to the next available transformer.  If I had plans of adding more lights to this area, I should consider sizing up even more to accommodate this.

If you have multiple wattage sizes, you will need to run the calculator separately for each wattage and add the total.

Minimum Transformer Size Needed =  Light Wattage x Number of Lights x 110%

Example:  I have (5) 3-watt lights & (2) 4-watt spotlights (shown above) that I plan to use, and I need a transformer.

Solution:  Use the formula for each wattage above to solve:

Minimum Transformer Size Needed =  3 watts x 5 lights x 110% = 16.5 watts.

Minimum Transformer Size Needed =  4 watts x 2 lights x 110% = 8.8 watts

Add the total:  16.5 watts + 8.8 watts = 25.3 watts.  A 60-watt transformer would work well for this application.

If math isn’t your thing, no worries.  We offer a calculator on each lighting product page for your convenience (see below).  You simply input the wattage of your lights and the quantity of lights and the calculator will determine this total wattage for you.  Take this calculated number and find the appropriate transformer for your needs.

Each product page will also offer related transformers and other accessories at the bottom of each product page.

Use our calculators below to determine the transformer size that you need.  Use the top calculator when all of your lights are the same wattage.  Use the bottom calculator when you have multiple wattages.