The output voltage of magnetic pickups varies between 100 mV rms to over 1 V rms for some of the higher output types. A hard strum on all 6 guitar strings can produce a larger output voltage swing, typically peak voltages of +/− 5 volts for single coil pickups and +/− 10 volt peaks on dual coil pickups.
That was stolen from Wiki..
Do you know what pickups you have?
Martin