For anyone interested in this type of stuff, I've built a retirement calculator to help analyze your financial situation and provide a realistic assessment of your projected retirement fund.
It's all open source (this is just a personal project built in my free time).
The quick story is that I didn't like any of the retirement calculators available online because they often gave very simplistic answers. Some never considered taxes, others didn't capture a persons entire investment portfolio, and yet others operated without any realistic assumptions about the market. Asking for the user to plug a 7% growth rate and projecting their wealth based on that number doesn't tell the whole story.
With that said, this is an evolving project, it needs more work, and I welcome all feedback. Some of the trends built into the model are proper inflation assumptions, wage inflation, tax bracket inflation, adjusted rates of return for a number of investment categories, and various trends on maximum contributions.
The end result is relatively simple,
Total Account Balance - Your total dollar amount at retirement, in today's dollars. Essentially, if you were to retire today, would this be enough to support your lifestyle?
Effective Annual ROI - This is the actual yearly rate of return across all of your investments. You should be able to see why simply assuming a 7% average growth rate can be terribly misleading. Retirement is a lot less about the interest and much more about consistently putting money away.
Rank - This is the most "fuzzy" feature on the site, but it's designed to show how well your ROI compares to other users in your peer group. The higher, the better. Important to note that it's entirely based on unverified data and compares ROI (and not the total amount saved).
I'll just add that there are certainly better tools on the market, particularly if you purchase a professional product. But this is quick and free, so why not.