For how long is chicken pox contagious for?

14 to 21 days. Chicken pox is contagious even before the rash appears and remain contagious till the last blister has scabbed.
About a week. Chickenpox tends to emerge in waves of new spots over a period of 2-5 days.The blister grows, pops & crusts usually within a single day. A person is considered contagious for 1-2 days before to 6 days after the emergence of the rash.