The standards that have us thinking about this in terms of % ownership of the company is part of the problem IMO. Future rounds and other factors can quickly ma

The standards that have us thinking about this in terms of % ownership of the company is part of the problem IMO. Future rounds and other factors can quickly make this calculus impossible or with 1000% error margin. IMO, the correct way to approach this is keep everything in terms of $$ values. There is available research online that can allow you to aggregate data for comparable companies on things like: "if the preferred shares price was worth $X per share at the series A, what was the that same share worth at IPO/acquisition?" It's still not easy to answer as the data is sparse and widely varying, but thinking in these terms normalizes the conversation around dollars and gets rid of the "what dilution might happen" part of the equation. For example, my company is in the open source data infra space. So while its hard to get very many data points, trying to get info about the preferred and common share prices at each round and all the up to IPO of companies like MongoDB, Hortonworks, Elastic, Cloudera, etc -- even though they all raised totally different number of rounds and IPOed at different valuations -- in aggregate you can start to build an insightful picture.