What’s the best way to measure your company?

Paul Graham (Co-Founder & Partner at Y Combinator)
Do Things that Don’t Scale

If there’s one number every founder should always know, it’s the company’s growth rate. That’s the measure of a startup. If you don’t know that number, you don’t even know if you’re doing well or badly. The best thing to measure the growth rate of is revenue. The next best, for startups that aren’t charging initially, is active users.