The long-awaited Defense Department retirement calculator has arrived, designed to help service members choose between the existing and incoming retirement systems as they plan their long-term financial future.

The calculator, labeled a "beta version" but available to anyone at militarypay.defense.gov/Calculators/BRS/, asks for basic information such as age, years of service, rank and estimated years of service at the time of separation and retirement. It fills in the blanks for items such as expected rate of investment return, life expectancy, Thrift Savings Plan contribution percentage and career progression, but users can alter those fields, and others, to tailor their results.

After the user enters all the data, the calculator will offer a comparison between the plans. The BRS total includes not only pension and government TSP match, but also the service member's TSP contribution – a factor to consider when evaluating the results.

The traditional-system total does not include any TSP contributions made by service members, nor does the tool offer an option to include those contributions in the calculations.

Regardless of your findings, you can't make the leap into the new Blended Retirement System until 2018. And not everyone has a choice: Active-duty members with more than 12 years of service as of Dec. 31, 2017, are automatically enrolled in the legacy system, as are reserve-component members with 4,320 or more retirement points as of that date.

The old system offers a larger pension check after 20 or more years of service than the BRS, but the new system provides matching contributions to the TSP that service members could collect regardless of when they retire. 

That's the core decision for the service member, financial advisers have said: determining whether they intend to stay for 20 years, and considering other factors beyond their control that would prevent staying until retirement.

The calculator allows you to consider the effects of bonuses and payments on the final numbers, but you don't have to factor those into the calculation. You also have the option of considering the effects of taking a lump sum under the new BRS.

The reform of the military retirement system became law in 2015 and takes effect Jan. 1, 2018. No one is automatically enrolled in the new system -- except for anyone entering the military on or after Jan. 1, 2018.

DoD has been rolling out a variety of education programs aimed at helping educating troops about the decision, including an online training program program available on Joint Knowledge Onlinefor those with a common access card. Family members and others without a CAC can also take the course at Military OneSource.

DoD also has offered courses for military leaders and for financial education professionals in the military community as well as organizations that work with the military community.

Defense officials stress that everyone must make the decision based on their own individual and family circumstances, and there are a variety of resources on base and off base to help.

Senior reporter Karen Jowers writes about military families, quality of life and consumer issues for Military Times. She can be reached at kjowers@militarytimes.com.