This article was updated on April 13, 2018, and originally published on March 19, 2016.

Social Security provides a critical source of income for retirees, so if you're approaching retirement, knowing how much you and your spouse can expect to receive in Social Security benefits is smart. Although the amount of money that couples receive in Social Security income varies depending on work history, income, and when couples begin receiving payments, the average retired couple is receiving \$2,340 per month in 2018, according to the Social Security Administration.

Are you likely to get this much money, too? Read on to learn how Social Security calculates its payment, and what you should do to maximize your benefit.

IMAGE SOURCE: GETTY IMAGES.

First, a quick bit of background

Many Americans approach retirement thinking that Social Security is a savings account that's similar to a retirement account, such as an IRA or a 401(k) plan. It isn't. Social Security is a pay-as-you-go system, and that means that the payroll tax you pay today covers the cost of current Social Security recipient's benefits, not your future benefit.

While Social Security accounts for 90% or more of income for about one-quarter of married retirees, the system was never meant to provide the lion's share of a retired couple's income. Instead, Social Security is supposed to act as a safety net. As such, it replaces about 40% of the average recipient's pre-retirement income.

How's it calculated

Now that we've covered those points, let's dig into the calculation Social Security uses to determine how much money you can receive in benefits in retirement.

First, Social Security uses a complex formula that converts income earned during your 35 highest-earning working years into today's dollars. Then, those adjusted incomes are added together and divided by 420 -- the number of months in 35 years -- to get an average monthly earnings number. That average monthly earnings number is then broken into chunks, and multipliers are used to calculate your monthly benefit at full retirement age, or the age at which you can claim and receive 100% of your benefit (more on that in a bit).

For example, a person who was born in 1956 would multiply the first \$895 in indexed monthly earnings by 90%, any amount between \$895 and \$5,397 by 32%, and any amount above \$5,397 by 15%. Once those calculations are done, the resulting numbers are added together and rounded down to the nearest dollar. That sum is a person's estimated monthly retirement benefit at full retirement age.

This formula is used to calculate benefits for the primary recipient, but it's also the number used to calculate a spouse's benefit, too. Generally, a spouse retiring at full retirement age can receive half of the amount that the primary recipient would receive at their full retirement age. If the spouse claims early, then the amount they receive is reduced.

For example, if a spouse born in 1960 claims benefits two years before their full-retirement age, they'd receive 41.67% of the primary recipient's benefit. It may also be helpful to know that, if a spouse's own work history results in a higher Social Security payment than the spousal benefit, then the spouse would receive their own benefit, not the spousal benefit. Sorry -- no double-dipping!

Admittedly, these calculations are complex, so the Social Security Administration provides a handy calculator that allows married couples to estimate their benefit. Alternatively, individuals can create a user ID and log into Social Security online to find out their specific benefit.

Image source: Getty Images