Simple retirement calculator

As I have often mentioned publicly and in my book, I have long preferred a simple rule of thumb I call the “4 house pension” to many of the retirement calculators I have seen online.  That said, I have started brushing up on my JavaScript to write a few smartphone-friendly pages to do quick cost-benefit calculations for decisions like Roth IRA conversions or SIPP vs QROPS UK pension transfers.   I appreciate your comments and e-mails on what other types of financial calculations you might like to see in a calculator like this. As a preview, here is one version of a super simple retirement calculator with very few variables and unrealistically simple assumptions:

• You save the same amount every year between now and retirement.
• You draw the same amount every year in retirement.
• All numbers are assumed to be adjusted for inflation to current dollars, so the assumed rate of return is a “real” (after inflation) rate of return.
• You earn exactly the same real rate of return every year with no volatility in your investments.