I was frustrated with some of the calculators that were out there. Some were too simple and some were too complicated or did not provide us with a variance for creating recipes.
I took the pros and functionality of the ones that met my needs and created my own. The nice thing about Simple Calc - as long as you have the final amount of the batch made, it can be easily replicated when sharing recipes. One of the major turn off(s) for me was the inability to input fractional percentages, this has been remedied in Simple Calc.
Some folks have created recipes using %, drops or mls. Some have actually created recipes using all three in the same recipe. Most calculators only accepts certain units of measure. The Simple Calc accepts them all.
My simple DIY Calculator available for free download.
Give it a whirl and let me know what you think.