Here are just a few questions: What's your current income? What percentage of your income are you saving for retirement right now? How might your income change over the years, and will you be able to save more?
Ultimately, how much money you'll need in retirement will also depend on these three factors:
1. When you retire
2. Where you retire
3. What you plan to do in retirement
You may still want to do something in your late 60s and early 70s that generates a little income. That said, the Ballpark Estimate calculator at www.choosetosave.org has a good online calculator or mobile app where you can fill out a worksheet that can help you quickly identify how much you need to fund a comfortable retirement.
If you want a general benchmark—a number to strive for—check out these "guideposts" suggested by Fidelity, the nation's leading retirement plan provider:
—Age 35: Try to have saved at least as much as your current salary by the time you are 35.
—Age 45: Have three times your salary saved by the time you're 45.
—Age 55: Save at least five times your salary by your 55th birthday
—Age 67: When it's time to retire, your goal should be to have saved at least eight times your ending salary.
(Read more: Planning for your retirement: Making your money last)
Fidelity says following these benchmarks should help increase the odds that you won't outlive your money over the next 25 years. Keep in mind, Fidelity assumes you'll save for 42 years—from age 25 to 67 with no break in employment—and that you'll be socking away 12 percent of your income a year by the time you're 37 to reach these goals. Also, Fidelity assumes your investments will grow 5.5 percent a year on average and your tax rate will stay the same when you retire.
But with a Roth account, you don't have to worry about the tax bite into your retirement savings. What's terrific about putting your retirement dollars in a Roth IRA (as you have been doing), is that the money will grow tax-free and generally can be taken out tax-free six months after your 59th birthday.
Still, you could be saving a lot more money in workplace retirement plans if available to you.
Contribute to a 401(k) or 403(b) plan (Regular or Roth) for retirement as well. The maximum contribution to a Roth IRA for 2013 (you have until April 15 to make one) and for 2014 is $5,500 or $6,500 if you're 50 or older. But this year you can contribute up to $17,500 to a 401(k) or 403(b) plan (and up to $23,000 if you're 50 or older).
Continue to make the most of your retirement savings. It's your money. It's your future.
If you have a question for me, follow me on Twitter @sharon_epperson. Just tweet your questions about how to better manage, grow or protect your money at #GetAPlan.
(Read more: Retirement funds and ramen noodles: Saving smarter in your 20s)