Hi. we have a 8 week collie pup who we picked up from a working farm. The mum and dad we both quite big collies, definatly over 20". I understand it was the bitches first litter.

Well my question is how big can i judge how big she will get when older. At the moment she is very small, compared to another small dog of mine who is 11-12" high (more 12" than 11) she is about half his size and has very small dainty paws. She was the smallest one of the litter. Is there anyway i can work out how big she will be, she is also quite thin not a typical porky pup, but i dont know her exact weight. Are there any sites or ways i can work out how tall she will become?

Not really if she was an average sized puppy then she would probably be the same size as her parents, but being the smallest puppy in the litter she could end up small or catch up & end up the same or bigger than her parents. A friend bred a Great Dane puppy that was 4 oz at birth & was always smaller than the rest of the litter, he ended up the biggest GD I've ever seen ! My first BC was the smallest in her litter & ended up the size of a big sheltie

I must warn you that there is Dwarfism in some Border Collie/Working sheepdog lines, but a dwarf puppy is easily recognizable by the time they are a few months old

Does the height matter, or are you trying to find out what her adult weight will be in order to calculate amounts for raw feeding? (I saw this on your other thread)

Whilst I was rummaging about on the internet the other day I found a calculator for feeding raw to pups.  Let me know if you want a link to that - I think I can find it again! I think the age range was puppy to 10 months, then 10-24 months then 2 years and over

The best way to estimate how tall your puppy will be is to look at her relatives, even then there are so many variances due to feeding, exercise, neutering etc. The size of the pup just now doesn't seem to matter, like MMs friend I've also had the smallest pup in the litter grow bigger than the rest.

My most recent pup wa s the smallest in the litter at 8 weeks and yet she is now the tallest by far and is the same height as her mum (als otall for the breed) at the age of 9 months.

my pup was the lightest in her litter when she left but is now one of the tallest bitches (although that still isnt large) she is just over 19" at 16 months old.  Her younger sister has measured into medium in agility so thats under 17". They're BCs by the way.

I tend to find pups have the majority of their height by the time they are about 6 months and may grow an additional inch but not much more after that.