I am doing my first yeast starter ever and am using a stir plate. I entered my numbers into both and came up with two very different results for viability. Yeastcalc gave me 89% which was enough cells ti cover my yeast requirement. On Mr. Malty it gave me a 71% viability and needing two packs to get the right count. The yeast is a Wyeast 1968 London esb. Mfg. date was January 13. Anybody have a preference as to which one they trust more? The guy at my LHBS said to use one pack as a starter and add the other one when I pitch. Three different answers for one starter. I hope it gets easier.