1 gallon batch and 1st time using washed yeast question

[HomeBrewKingPin]

Hello,
I have been home brewing on and off for a while and have moved to recently to one gallon
batches (more brewing , less alcoholism) i twice washed the yeast from my last batch
there appears to be 1/2 oz of solid yeast on the bottom of a half qt mason jar and the beer+ wash liquid on top.

a white labs vial contains around 30 ml of liquid yeast.
i plan on decanting most of the top liquid and swirling then pitching the slurry no starter
and eyeballing the amount.
The Question
is there any way i can guess how much viable yeast i have?
the mason jar looks to have .5 oz of clean looking solid yeast i do not want to
way over pitch.

 

[HomeBrewKingPin]

Hello,
I have been home brewing on and off for a while and have moved to recently to one gallon
batches (more brewing , less alcoholism) i twice washed the yeast from my last batch
there appears to be 1/2 oz of solid yeast on the bottom of a half qt mason jar and the beer+ wash liquid on top.

a white labs vial contains around 30 ml of liquid yeast.
i plan on decanting most of the top liquid and swirling then pitching the slurry no starter
and eyeballing the amount.
The Question
is there any way i can guess how much viable yeast i have?
the mason jar looks to have .5 oz of clean looking solid yeast i do not want to
way over pitch.

Hi again
found my own answer after some more searching on the forum
http://www.mrmalty.com/calc/calc.html
Mr malty yeast calculator is a tool that takes out some of the guess work.