Skeebo2 has a point, but if you think you might retire before the apocalypse he describes, I would suggest hiring a personal financial planner. Not just someone who will try to tell you what to invest in, but someone who understands retirement planning and all that it entails. After flying with several guys who were approaching retirement, and were worried about not knowing how much money they'd need and whether their health care coverage was going to be sufficient as they got older, I decided to look into all of that on my own. I quickly realized I didn't have the expertise or time required to manage multiple pension accounts, life insurance options, long term health care plans, my established investment portfolio and other assets we've all probably accumulated. At least not well enough to maximize the potential of each. I've been working with mine for over a decade now. It costs money, but I cringe to think about all the things I wouldn't have thought about if I had just assumed that I'd get my retirement $hit together a year or two before I retired by attending one of those ALPA retirement briefings. Don't get me wrong, those are great, but too many guys find out in one of those sessions that they've misallocated their assets for years and it's almost too late to catch up.
If you are looking for an online retirement calculator, then you probably have a lot of the same questions I did. Go the next step and find a human who can take a look at all your variables. It's worth the money.