Oh, I hope I didn't confuse anyone, the link said no more than 25% percent, I'm not sure how you would figure out grams though.
If you look on the back of the label on the pellets or seeds, it will tell you the protein content. I've never seen them measure protein by grams, I guess percentages makes it easier.
I think Harrison's is 18%, Roudybush is about 12%, Seeds are about 14% generally, Nutriberries is about 12%.
I think you have to add the percentages up that are given to them in a day. The problem is though, it doesn't have a serving size on the back of the label, maybe a couple table spoons is one serving for parakeets, I'm guessing?
I would guess since seeds and pellets are both high in protein, you would have to alternate the two everyday just to be on the safe side so they're not getting too much protein. And veggies you don't have to worry about, I'm pretty sure vegetables don't contain any protein in them. I think they add waaay too much protein in these foods, it's so easy to give them too much.