I actually built an app to do this kind of calculation. It walks you through each of the calculation steps and variables involved, along with context: http://w

I actually built an app to do this kind of calculation. It walks you through each of the calculation steps and variables involved, along with context: http://www.optionvalue.io/ http://www.optionvalue.io/ The main pieces of information you need to know are: * Total number of outstanding shares * Strike price The main thing you'll need more detail on (though perhaps you have it) about is whether the $1300 number is the per-share value (= $1B / number of shares) or a per-share strike price (the amount you have to pay to exercise each share). The base assumption you'll want to make when doing the calculation is that the company exits at the current valuation. Obviously it could exit for a lot more or a lot less, but the last VC valuation is a reasonable E(x), and while you can add an asterisk around how VC shares work vs employee shares, it should be accurate +-10-20%. The other big thing you'll want to know is how long it could be until the company IPOs or exits and you can actually get cash. A good optimistic scenario, if they are a SaaS startup, is to ask them about 2015 and 2016 revenue and figure out how long it would take them to get to $200M revenue at current growth rates.