I have 12 led strips that each came with a 3 amp/12vDC power supply. I want to connect all 12 strips to one DC power supply. How do I calculate the size power supply I need? Do I increase the wattage or the amperage?

  • \$\begingroup\$ First you would have to figure out how much current the led strips really use, maybe from a datasheet, maybe by measuring, because the power supply that comes with it is probably over-rated. Then multiply the amps by 12. Or just buy a 36A /12VDC unit. (And Watts = Amps x Volts. So you can not increase the one without the other) \$\endgroup\$
    – Trevor_G
    Mar 7, 2017 at 19:18

1 Answer 1


Do I increase the wattage or the amperage? Both! Watts are a product of volts multiplied by the current. P=I X E where P is watts, I is current and E is voltage. You will need to connect your LED strips in parallel, so 12 strips at 3 amps each will be 36 amps. And 36 amps times 12 volts will be 432 watts.


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