Source: Katie Brockman - USA Today

For most retirees, Social Security benefits are designed to replace approximately 40% of pre-retirement income; however, many seniors depend on their benefits to cover the majority of their bills.

Roughly 1 in 5 married couples and almost half of unmarried individuals rely on their monthly checks for at least 90% of their income in retirement, according to the Social Security Administration. For these retirees, there's a lot riding on Social Security benefits – and the size of those checks could make or break retirement.

Read Full Article: These 3 Social Security strategies could increase your monthly checks