Mark Geragos is going out on a limb and taking a stab at how long Diddy will spend behind bars for his recent conviction on prostitution charges … and if he’s right, Diddy will be a free man sooner rather than later.

Harvey Levin and Mark examined the next steps in the Diddy case Wednesday on the “2 Angry Men” podcast … and the famed defense attorney explained why he thinks the judge will sentence Diddy to between 12 and 18 months behind bars.

Diddy’s already spent almost 10 months in jail and he’s still in custody pending sentencing … and his time served will go towards his sentence.

Mark’s daughter, Teny Geragos, was the co-lead attorney on Diddy’s defense team … and we dragged her on to the show and tried to congratulate her on the big win and her pregnancy … and ya gotta see Teny’s reaction.

As you know … Diddy was acquitted Wednesday on charges of racketeering and sex trafficking, and jurors found him guilty on two lesser charges … two counts of the Mann Act — transportation for prostitution across state lines.

Diddy faces a maximum sentence of 20 years … but it’s unlikely he gets sentenced to the max. His defense and prosecutors are divided on sentencing guidelines … his attorneys say sentencing guidelines start at 21 months, with prosecutors saying the sentencing guidelines start at 51 months.

Mark’s sensing a sentence close to time served … but it’s going to be up to Judge Arun Subramanian … and there’s a hearing July 8 regarding a potential expedited sentencing timeline.

Diddy got on his knees and prayed in court after the verdict was read … and ya gotta figure he’s praying Mark’s right on this.