Yeast Starter - Ratio Question

I keep seeing a pretty common theme of 1/2 cup of DME to 2 cups of water for a yeast starter. And its a rule of thumb I always followed, and I havent really ever paid attention to much detail beyond that for the starter. My starters have always been ok, but never great.

Well, I upgraded my kit and got a stir plate and a 1L Flask. I did 1 cup of DME to 4 cups of water and ended up right at 1L. I boiled for 15 minutes, cooled and through it in the flask and thats when I noticed that I had a little less than 900mL left, which is 10% boil off. So, knowing that the sweet spot for a yeast starter is 1.035-1.040, I checked the gravity reading and I got 1.055.

So my question becomes, the 1/2 cup DME to 2 cups water, is there corrections that must be made for boil off? I simply topped my starter off with water and got it perfect, but this is the first time I have topped it off with water, so curious if this is common or if I need to adjust my water for boil off.

 

I have found that it is easier to use the metric system with a 10:1 Water/DME ratio when making starters. For example, if you want to make a 2000 ml starter, just weigh in 200 grams of DME and then add water to bring the total volume to 2000 ml. That should give you the right OG (1.035-1.040) every time. As far as boil off is concerned, I always add a little more water than my desired starter volume to account for the boil off.

 

The optimum starter wort is a 10:1 ration of brewing water to DME. A one liter starter wort would have 1000 milliliters of water with 100 grams of DME added to the water.

Weighing your ingredients is more accurate than using volume measures. A good digital scale is about $20 at Walmart. Digital scales are very good to have when dividing bulk hops by the gram.

 

Forgot to add this to my previous post. There isn't any need to boil the starter wort for 15 minutes. Pasteurization occurs at about 165°F. Remove the water from the heat when it comes to a boil and stir in the DME.

 

This^^^^^^