Sources: NFL salary cap $177.2 million per team for 2018 season

— -- The NFL's salary cap has been set at $177.2 million per team in 2018, up from $167 million last year, using a calculation based on the league's revenue, sources told ESPN's Field Yates.

This is the fifth straight year the salary cap has increased by at least $10 million. The 6.11 percent increase is the smallest percent increase for the cap from year to year since 2013's 1.99 percent jump.

But since 2013, the cap has risen more than $54 million, from $123 million to $177.2 million, an increase of 44.1 percent.

Teams were notified of the salary cap and the numbers for franchise tag designations on Monday. There is an exception for players franchised for a second straight year.?

The NFL's collective bargaining agreement allows teams to carry over unused cap space from one year to the next. It also establishes a spending floor. Every four years, teams must spend at least 89 percent of their cap space in cash to avoid a CBA violation.

Free agency begins March 14, with the start of the NFL's new league year. Teams that are over the cap must clear salary by that date. Currently, three teams are over the cap: the Philadelphia Eagles ($11,210,390 over), Miami Dolphins ($8,874,165 over) and Kansas City Chiefs ($3,285,981 over).

The Cleveland Browns have the most room under the cap, with $108 million to spend.