You'll have to forgive me for not knowing the full name of the person who invented this DPS calculator (Marcostyle?), but my Clan and I have been using it since launch. It's a simple tool, that doesn't require much input from yourself. Basically, you key in your attributes (hit [i] in game, click on the target, and scroll down to them). Once you've done so, the DPS Calculator will throw out your Final DPS. 

What's particularly useful about this spreadsheet is the fact it's not only accurate, but you can compare multiple builds that you have. It might take a few minutes to input your stats, but it's well worth it if you're wanting to know wether or not you deal more damage with X, Y or Z. Hit the link below.

The Division 2 DPS Calculator