The birth chart - filled with all sorts of indecipherable squiggles, lines, and symbols - is the primary "sky map" astrologers start with when performing astrology readings for their clients.
Good News/Bad News
What's the bad news about using one of these free online tools? The bad news is that not all online tools designed for calculating your birth chart are created equal. When doing my search for the best online chart calculation tools - I discovered to my great shock that there were a few online tools that (not mentioning names) made some whopping big errors, a few that made minor errors, and several that made quasi-minor errors.
The other bad news is that one teeny, weenie, little mistake on your part can totally skew, distort, and throw off the results of the most accurate chart calculator. Online tools, in spite of being extremely accurate and useful, are (like any other complex software application) woefully unforgiving when the user fails to perfectly follow directions and/or incorrectly enters the required data. Mistakes happen... and I assure you, that in my time, I've made more than my share.
So, here are my best suggestions regarding the calculation of online birth charts…