A lot of plans will send you a letter at the beginning of the year saying how much RMD you need to take. Did you just turn 72? Will this be your first RMD?
See this IRS FAQ on RMDs….
http://www.irs.gov/Retirement-Plans/Retirement-Plans-FAQs-regarding-Required-Minimum-Distributions
Here is a worksheet to calculate the RMD
https://www.irs.gov/pub/irs-tege/uniform_rmd_wksht.pdf
IRS Publication 590B on IRA Distributions
https://www.irs.gov/pub/irs-pdf/p590b.pdf
