Most allow you to use only a percent of flavor to the total mix, and that % of flavor is derived by the recipe. Mine allows for up to 5 flavors in the recipe that then calculates based on parts to figure out how much the % to add in.
So if I wanted to make spice cake for example that uses 5 flavors you go to section 6 and enter the five flavors and how many parts of each and it will tell you how much of each to use based on the flavor % defined in section 1 and then converted to ml in section 2.
This way you do not have to mix alot of flavor together for a small batch. It will calculate how of each you need to add together based on the desired % of flavor you want to use in the mix.
Hope this helps, oh and the download link for my calculator is in my signature. You must have excel or download "Open Office" which is free at filehippo, just click the download link in the upper right corner here:
Download OpenOffice.org 3.2.1 - FileHippo.com
Dan