Wisdom of the Crowds question (or an answer for a new guy like myself.)

I am going to get riser handlebars and chop them down. Doing some research, I notice that there are alot of different sizes.

While I know ultimately (it's up to me) is there an industry standard riser handlebar size for fixie/ss bikes?

Not the width - but the amount of height. I've seen 20, 30, 40 and 50mm Rise.

Is 30 the standard? 50 too much?

Many thanks,
CD