^I think the first post of evil's is good advice - As they are now, given that with good trimming, his feet should change enough within only a few trims, so that boots you get now won't fit well, shortly. And possibly may not fit wonderfully even now. So unless you can buy a cheap set, I'd wait until he's had a few good trims, to correct those heels, before measuring/buying boots. Unless he's sore in the paddock & needs them for 'rehab'.
Yes, he has 'run forward', overlong heels, very probably stretched toes too, tho need more pics & without tape in the way(see link in my signature if you want to post more pics) to get a really good idea. Heels also appear quite uneven, the way they've been trimmed, and bars are also overlong.
If you do want to buy boots for him now, I'd measure back to the widest part of the frog, as if the heel platforms were back where they should be, although you may be able to lose a half " or so of toe off that length, if that were backed to where it should be. *Tho without clear pics, that's only a guess.
The second of Evil's posts I do not agree with at all(sorry Evil) - I don't think it's at all fair to base an opinion on the farrier on one picture, particularly this one. Especially knowing the horse is new to you, newly deshod etc. Yes, there are 'issues' that need resolving(heels & bars appear 'too long' & heels appear uneven), but without knowing what the hooves looked like before, what has been done, other angles etc, who knows whether your farrier should have done any different for that one trim.
Last edited by loosie; 11-28-2018 at 11:12 PM.