Most Americans significantly underestimate their health care costs in retirement, according to a survey released today by Aviva USA in collaboration with Mayo Clinic.

Nine out of 10 people expect to spend less than 20 percent of their monthly retirement income on medical and dental expenses. Seven out of 10 expect to spend just 10 percent or less.

Retirees should be prepared to spend about 30 percent of their income on health care expenses, according to The Urban Institute.

Only four out of 10 people surveyed said they are or will be financially prepared for retirement - and that's potentially without fully realizing the true costs.

Other findings:

  • One in six respondents said they go to the doctor less frequently than once every two years.
  • Only one in eight Americans say they are currently unhealthy. More than 35 percent of American adults are obese, according to the Centers for Disease Control and Prevention.
  • Nearly a fourth (23 percent) expect their health to be improved in retirement.
To read the entire survey, click here.