Mr. Malty - I am missing something
 

I understand how to run the calculation, but it seems there are two key pieces of information missing with this tool.

1) How do I know how long it will take for the yeast starter to be ready?
2) How do I know the ratio of DME to water for the yeast starter?

1) Once it is done fermenting, typically for starters it is 12-36 hours. You will see the activity stop. Then either pitch or cold crash and decant and then pitch.

2) You want it to be around 1.040 so whatever ratio gets you there. I use metric for starters and I think it is 100g DME in 1 liter gets you close to 1.040.

Can someone give me that measurement in cups / quart?

About 3.5 Oz of DME to 4 and 1/4 cups.

I always weigh mine out but just guessing you would be somewhere around 1/2 cup of DME to 4 cups water.

Volume isn't a great measurement for powders, as there are a number of different factors that can influence the relationship between weight and volume. But, as a rough estimate, I get about three cups of DME per pound where I am. However, you really do want to buy a scale.

Exactly, way better to weigh than to measure. The proper ratio for ~1.04 wort is 1g DME/10 ml water.

^ exactly! 10:1 water to DME by weight.

Or... for all you Americans out there, use 3.5 ounces of DME per 1 quart of water. ;)