Social Security Commissioner Dorcas R. Hardy is hoping new, individualized financial statements for workers of all ages will demystify her program and encourage people to plan ahead for their retirement years.

The personalized earnings and benefit statements will give people an approximate idea in today's dollars of how much Social Security will pay them each month when they retire or become disabled, or pay their families if they die.It will be available free by mail to anyone who fills out a form requesting the "Personal Earnings and Benefit Estimate Statement," which President Reagan promised in his last State of the Union address.

Those interested can call a toll-free number - 1 (800) 937-2000 - to request copies of the disclosure form, SSA-7004.

Hardy told a news conference Thursday that once the request forms are received, it will take her agency two weeks to three weeks to send back a lucidly written, computer-generated statement with a wealth of data on what that person has paid in and what he or she can expect to draw out.

Hardy embarked on the project after taking the helm of the agency two years ago, convinced that Social Security was not only the government's largest program but "probably the most misunderstood."

Social Security pays out more than $200 billion a year in cash benefits to 38 million retirees, disabled workers and their families. Its payroll tax also pays for the $70 billion Medicare program.

"By putting a precise dollars and cents value on those benefits, and individualizing it for the person making the request, Social Security will no longer seem so mysterious and complex," she said.

Hardy said her hope is that "this one sheet of paper" will give Americans "a far greater understanding of the Social Security system" and encourage them to recognize the need for private pensions, adequate insurance and personal savings.

Some private companies charge people for making the kind of estimates that Social Security now will be doing free.