These free tools will calculate your Social Security benefits

When to claim Social Security is one of the most important decisions retirees can make. Many websites offer free estimates of how much you may receive depending on what age you decide to take benefits.

Researchers from the Social Security Administration reviewed six popular online tools to compare their estimates of what you may receive when you claim at the earliest possible age of 62, your full retirement age and at age 70, which usually maximizes your benefits.

Results from the free calculators were similar, but some differed by hundreds of dollars per month in the test cases. Generally, the more complicated the financial situation, the worse these freebies performed.

Here are pros and cons for each tool, according to SSA researchers Patricia Martin and Dale Kintzel: