How skinny is too skinny?

 Looking down from above he goes in and I know he's underweight from the poster at the vet's office. (Oliver hasn't seen a vet with us yet). How long should it take him to plump up if he's free feeding dry food (Friskies atm but I'm going to get him one with higher protein {is it 43% protein?}) and a whole package of wet food in the morning. We do not have a scale so we haven't weighed him nor can we weigh him for progress. 

That's really hard to say. Can you get a baby scale from a garage sale somewhere? Then you only have to take him into the vets once to find out what he should weigh and you can do the rest yourself.

Do you have a regular scale at home by any chance? My scale does 1 decimal so I can get a pretty accurate reading. I will usually weigh myself 2x (to make sure the scale is showing the same weight for me) and then I will pick my cats up and hold them in my arms and weigh myself again, then figure out the difference. This has been pretty accurate in my experience (compared to the vet's baby scale).

My baby Chacho was pretty skinny when we brought him home. It took a couple weeks before he got to what I thought was a normal weight. I pretty much go by sight, if he looks too skinny then he probably is.  They way I see it, you should be able to feel ribs when you pet their sides but they shouldn't be jutting out. You should see some defintion from where the ribs end and the hips start but that defintion shouldn't be massive, if there's no definition then chances are the cat's overweight. SO if you feel their bones too easily/no meat on the bones = too skinny.   If you can't feel any bones/no definition = too fat.      Its okay for senior cats to have a little extra weight and it is typical for kittens about 5months old to look a little skinny and lanky (to a point.) They're in their awkward teen stage and like a lot of human teens they look a little lean and lanky but the rule should still be the same, just expect them to still look skinny just because their proportions are a little strange. (lean and awkwardly long looking legs lol)

I can try to find a scale online.. There's only a food scale here and it's simply not big enough. Oliver would do better with me holding him while I re-weigh myself

 My family is all split up now, my mom doesn't have a scale and my younger sister does but she lives too far away for it to be of any benefit trucking it around town. If I get my paws on a scale, how big should he be?? An adult male DSH??

  Now I don;'t know... He looks thin if you're looking down at him. His sides cave in a little but when he plops on the floors to sleep or play he's got a belly. It's more skin than belly I think but .. Here, I'll show you- 

See, he looks chubby but he;s light and when he's standing up that flab is gone mostly