Do I really need a 5 litre starter?
 

I have a kit Millennium Falcon kit from AHS that I got about a month ago and I have kept the yeast in the fridge since it got here. I used HomeBrew Calculator on my smart phone and gave it the date I ordered the kit and it said that the viability of the yeast would be 75% and that I would need a 5 liter starter. That seems excessive and on top of that, I only have a 1 gal jug to do my starter. I do have a homemade stir plate that will keep 3 quarts of starter agitated.
A couple of things I am wondering about: is the 75% viability assuming that I left the yeast at room temperature the whole time and how can I make a 5 L starter with a 1 gal jug?

Then I went to Brewzor Pro BETA on my smart phone and put the same information in and it also said 75% viability but that I only needed a 1.5 qt starter. I can handle that.

Who do you believe?

Mr. malty's calculator says a 2.5 liter starter.

Mr. Malty said with a OG of 1.065 making a 5 gallon batch with yeast that's 75% viable the starter size should be 3.83 Quarts assuming you use your stir-plate.

If you get a fresh yeast vial with 96% viability it says you only need 2.77 Quarts.

I don't know where you are getting these numbers from. The kit is a 5 gal ale. @ 1.065. at 75% viable with stir plate you need a 1L starter.

The viability is based on proper storage.

Convert L to quarts. The OP used quarts in his question.

The OP used Liter and quarts, good catch. He asked if he needed 5l and mentioned what he had available in quarts. The responses came back for both quart and Liter... But really there is not much difference. A liter is less than 2 ounces more than a quart. I would safely say it's OK to make a 1 quart or 1 liter starter and it will be fine.

Thanks. I'm glad I asked. 5L just seemed like way too much.
I'm going with a 3 qt starter because I'm pretty sure that won't be too much and it is as big as I feel comfortable with in a 1 gal jug.
It is interesting to see all of the different answers the various caluclators give.

You want to input the date that's stamped on the yeast, not the date you ordered the kit. I've bought yeast that's been 2-3 months old before.

With Wyeast you enter the date on the package. When using White labs enter the date four months prior to the package date.

I used a packet of yeast dated February (2012) with the brew I made last weekend. I used yeastcalc.com to find what size starters to use (two steps) to get my yeast cell count needed for the brew. I had enough time to get the starters made, with enough cold crash time between them and have it cold crashed before needing to pitch it. Fermentation went active within the normal amount of time (~12 hours from pitching).

I use a stirplate for my starters, so I can make significantly smaller ones (than without a stirplate). With a two step schedule, I only needed to maker a 1.5L and 2L starter to get the cell count needed.

Moral of the story, you're better off with a stirplate and using a good calculation tool/site. Planning far enough ahead to be able to make a two, or even three, step starter will get you where you need to be much easier. Plus, you'll use less DME with that combination (stirplate and more than one starter step for older yeasts).