How long are the socks with using "Magic stripes"

[Carla1019]

I was getting ready to knit up a pair of sock with the Lion Brand yarn" "Magic stripes"

Can anyone tell me how much yarn is going to be let over? I was wanting to make my sock longer then the pattern called for, and was wondering if I will have enough.

I am using the pattern on the back of the yarn. I am wanting to add about 6 in, to it. I think from the ankle up is about 6 in. on the pattern. I want it to be about 12 in. from the ankle up.

Thanks