I use this freeware program:
http://www.joshmadison.com/software/convert/
It allows you to convert just about any units known to man. So I convert
milliliters to teaspoons, and mix up the fertilizer in my kitchen. This isn't
rocket science; it doesn't have to be exact.
As for KNO3...I just drop it in dry, a quarter teaspoon at a time.
Leigh
http://www.fortunecity.com/lavender/halloween/881/