Gucci Mane won't get out of jail until late 2016 -- according to a plea deal the rapper just struck in exchange for copping to a gun possession charge.
Gucci pleaded guilty Tuesday to possession of a firearm by a convicted felon. The charge carries a maximum sentence of 10 years in jail, but under Gucci's plea deal, he's only expected to face 39 months ... minus 10 months credit for time served.
Gucci will officially be sentenced in July.
Gucci's been locked up in ATL since September after cops arrested him for packing a loaded handgun (as well as marijuana).
In addition to the jail time, Gucci also faces a fine of $250,000.