There's no way to sugar-coat this: It will cost a lot. The exact amount can vary quite a bit depending on how healthy you are, whether you receive any employer-provided retiree benefits, and other factors.
One recent survey found that the average retiree who receives at least some health insurance coverage from a former employer pays monthly premiums of $552 per month ($6,624 per year) if under 65 and $227 ($2,724 annually) if over 65. (The big drop after 65 occurs because your employer is going to make sure you enroll in Medicare at that point and then reduce the coverage it provides you through the company plan. Yep, this is totally kosher. A Supreme Court ruling a few years ago said it was perfectly fine for companies to reduce benefits to retirees over the age of 65.) If you get no help from your former employer, your costs will probably be much higher.
Medicare does kick in once you are 65, but there are costs for that coverage, too. And many retirees choose to buy so-called Medigap policies that provide coverage above and beyond what is offered through Medicare, or Medicare Part D prescription drug coverage.
Add it all up, and you need to get serious about stashing away some money today to help cover your health costs in retirement. Even when you are covered by Medicare and any other health insurance, you still are going to have to pay for some costs, including premiums, deductibles, co-pays and - most importantly for many retirees - prescription drugs.