lee is wrong. it is much harder to interrupt a DC circuit than an AC circuit, so the DC voltage and current rating of a switch are lower than for AC. The reaason is that on AC the current is interrupted when the current passes through 0. The energy (heating) the switch has to handle is low. For DC operation the current does not pass through 0, so the energy is much greater for DC.

Switch Current rate is the contact maximum current rate it can handle. In general practice, 125V ac 3A switch is good to run any DC current not more than 3A.

The switch will be fine for your application.

If you were trying to use a low voltage switch on high voltage, think twice. Then forget doing it!

rick is right dc is more difficult to interrupt

I have a push button switch that is rated 3A @125VAC. I'm running it in a circuit that uses 4v dc, is there any way of figuring how much current it can handle at those levels?

I assume the rating is energy related, 3 amps at 125 volts would be 375 watts, in 60hz pulses (because AC). 3 amps at 4 volts would only be 12 watts, but continuous (because dc). Does that matter much? Or could it theoretically go to the full 375 watts on a dc source? (I would only be running it at max 20 watts)