When should I begin saving for retirement?

A penny saved is a penny earned, but a penny saved today is a penny potentially earning more. Use this calculator to determine how much more you could accumulate at retirement by beginning your savings plan today rather than waiting.
Savings
Current age 
Anticipated retirement age 
Annual savings amount ($) 
Annual saving increases (%) 
Assumptions
Before-tax return on savings (%)help
Marginal tax bracket (%)help
Compounding/savings frequency