preamplifier

i'm desigining a microphone preamp which should give a gain of 40-60dB.
what is line level?
how do i calculate the line level in relation to gain?

Line level is from 100mV to about 330mV.
A microphone's output is about 5mV to 10mV when speaking about 10cm away. Then the gain of a preamp needs to be reduced to 10 times which is 20dB or 33 times which is 31dB.

My Sound Level Indicator project has a total gain of 1820 which is 65db and can pickup the sound of a pin dropping on the floor pretty far away. It has 20dB of automatic volume control so it can also display loud sounds.