How much of jiu-jitsu is useful for self-defense?

Most of it, as long as it is taught with the street in mind and not a points table.

The parts that carry over are the least glamorous parts. Breaking a grip off your wrist or your collar. Keeping your feet under you. Getting up off the ground without turning your back or planting a hand somebody can grab. Not getting flattened out and pinned. If you never learn another thing, you are already ahead of nearly everybody.

Here is why it matters so much. Real trouble closes fast. The distance where punches live lasts about a second, and then you are tangled up with a person who is holding on to you. That is jiu-jitsu’s distance. Nothing else prepares you for it.

The parts that carry over worst are the sport habits. Sitting down to play guard. Positions that only work because nobody is allowed to punch. Anything that assumes clean mats, one attacker and a referee counting points. I train no-gi with strikes in the picture, which changes which positions you hold and which ones you never enter in the first place.

And be clear about what you are training for. Self-defense is leaving. Getting up and walking away beats any submission you could ever hit, every single time.

Getting back to your feet is the most valuable thing on that list and it gets its own answer. What to do if you end up on the ground walks through the order I teach it in, and it is usually the first technical thing a student gets from me.

Grip breaking pays off fastest. A wrist, a sleeve, a bag strap, a hand in your hair. It is mechanical, it comes straight out of grappling, and you can have the basics of it inside one session. See what to do when someone grabs your wrist.

The piece most pure grapplers are missing is the range just before the floor, where you are both upright and holding on to each other. What the clinch is covers it. More real situations are decided there than anywhere else.

How fast all that comes together is in self-defense in a few sessions, and how much contact is involved is in will I have to get hit.