I follow this site for moon phases, but I also have an app. This site says about 13% percent but the app says 3%.
I did a full moon spell using this site during the last cycle (which was very effective) and I wanted to do a new moon dedication this phase, but I thought it was tomorrow, and I am not able to do it tonight.
I'll keep an eye on the sky anyways, but why is there such a margin? Asking for any other's experiences, etc.