From Longman Dictionary of Contemporary Englishthat’s about it/allthat’s about it/allspokenALL/EVERYTHINGa)used to tell someone that you have told them everything you knowHe was a quiet chap, married with kids. That’s about it, really.b)used to say that there is nothing else availableThere’s some cheese in the fridge and that’s about it. →about
Examples from the Corpus
that’s about it/all• I've seen her around a few times, but that's about it.• There's some ham in the fridge, and that's about it.• Behaviour in a vacuum may be very interesting but that's about all.• I can tell the difference between a sparrow and a swan and that's about it.• Oh well, that's about it.• Soundblaster effects such as laserfire and explosions are terrific but that's about it.• That's about it for this month.• That's about all I can tell you.• Unfortunately when it comes to originalitythat's about all the game has to offer.• They're very big, and they're very expensive, and that's about all you can say for them.