No idea, not a lot I dont think. He's a TB but I think of him as a medium weight TB so he's not as big boned as the old fashioned chaser/hunter type TB but he has more bone then the typical stick insect flat racer TB. Mine is probably your ideal event type TB. He'd an allrounder and I do a bit of everything with him (including BD and hopefully next year some low level BE and BS as well as RC and showing).
My late mare was also a TB she was very petite and only had 6 inches! She wore pony sized boots. She was also an allrounder who did RC stuff, showing, BS, unaff dr, hunter trials and sponsored rides. She was as tough as old boots and as sound as a pound.
My horse before that was an ArabxWelshxTb he had similar bone to my current chap and he was primarily a showjumper but he was also my pony club event horse. He was quick! As was my mare and my current chap. My current chap especially can really shift.
I don't take much notice of bone tbh. I'm fairly lw so I don't need something chunky and get away with a stick insect. I also learnt in my lectures at Hartpury that it's not how much bone a horse has in regards to soundness but bone density. So just because a horse is light of bone doesn't mean it is necessarily weaker
Henry has just over 10, he does a cracking job of being a field ornament Although has done everything in his previous life as a semi-useful member of society.
Mally, I would guess just over 8. Her sire has 8.6 inches and they look identical, although I've not seen him in the flesh. Hopefully she will be a slightly more useful member of society and do a bit of everything with slightly more height