The 49ers are just $590,303 under the NFL salary cap after the trade in which they acquired wide receiver Stevie Johnson from the Buffalo Bills, a source said.

Johnson has a cap figure for the 49ers of $3.925 million for the 2014 season.

The 49ers will pick up $6.6 million in salary cap space on June 1 when cornerback Carlos Rogers is wiped off the team’s books. The 49ers designated Rogers as a post-June 1 release, meaning they do not gain the official salary-cap clearance until that time.

Only the Pittsburgh Steelers ($311,000) currently have less cap room than the 49ers.

The 49ers are likely to make some cap adjustments this offseason to sign their remaining draft picks and, perhaps, quarterback Colin Kaepernick to a lucrative contract extension.

The 49ers would like to complete Kaepernick’s new contract before the start of training camp in late-July. Quarterback Joe Flacco had a first-year salary cap figure of $6.8 million after signing a deal that averaged $20 million a season last year with the Baltimore Ravens. Kaepernick currently counts $1.63 million against the 49ers' 2014 cap.