LED Matrix

Hey Guys. Sorry if this is a stupid question but bear with me.

I am trying to use and LED Matrix to use as a bike light and am stuck when choosing the correct resistors to use with it. I am going to be using a Arduino Nano to control the matrix. The matrix it self is a 8x8 matrix and has a Vf= 1.85V and a If of 20mA. I am assuming that the Arduino is supplying 5V as this is the battery voltage that I will be using. Now my real question is is using a 157.5 ohm resistor correct and also what power rating do i need to choose or what type of resistor as there is a huge choice when I am buying them. Thanks for the help :)

The best way to drive an 8 by 8 matrix is to use a MAX7219 chip designed especially for the job.

This then requires one resistor and a couple of bypass capacitors. No extra driver transistors. All information on the resistor is in the MAX7219 datasheet. Plenty of example sketches to use it, and one or two I can provide. :D