net carbs

Either in your head or you could use this on a desktop:

http://www.reddit.com/r/keto/comments/27vrmg/mfp_macro_no_longer_working_chrome_has_disabled/

You can't change it so that it says 20 carbs for the day.
You just log it like normal and minus your fiber from your carbs, making sure you dont go over 20.
I try and find the foods on here that already say net carbs out to the side.