I think the chart below is excellent. Its from FourPillarFreedom.com (a blog I’ve got to start reading now) that was linked to by The Simple Dollar. It shows, at certain income and spending levels, how many years it will take you to reach FI (assuming the 4% rule and a 5% interest after inflation). I believe it also takes into account taxes, etc. in the annual spending (i.e. your annual spend should include your taxes)
Many folks find it difficult to explain to people why they should save so much, and how it takes effort and sacrifice to reach our financial goals. This chart makes it a little easier to explain to people how long they would have to work in order to retire/reach FI.
Four Pillars has a lot of other tools (listed under his “Visuals” area) that help to show many of the FI concepts.
Check him out.
Mr. 39 Months