Safety factor of a bolt

It's been forever since I've done one of these and I have a problem where I need to ensure the bolts I'm using will stay bolted at a given upward pressure. I know the bolt diameter, thread pitch, grade, and its UTS. I also know the block thickness. Finally, I have the upward force in kPA.

From what I recall the bolt safety factor is basically ultimate stress / allowable stress, right?

If that's the case, is the allowable stress the upward pressure (or force) on what is being bolted down? And is the ultimate stress basically what the bolt can withstand?

Any input is appreciated. It's been a while since I took statics.