This is the natural aspect calculator. Natural aspects are an idea that springs from the fact that regardless of whether or not two planets are in aspect, they still have a relationship with each other. This program calculates that relationship in the most natural way possible. It determines into how many pieces you would have to evenly divide a circle in order for one of the divisions to fall directly on the distance between the two planets. In this instance, the aspects should be read as the portion of a circle (in longitude) that it takes to get from one planet to the other. In this way it could be thought of as arc length between the planets. In this system, there is no such thing as a non-aspect. A full-length article detailing natural aspects is available here.

The Method option above refers to the method used to calculate distance. GeoDist is geometric distance. This method treats the ecliptic like an x-axis and latitude as a y-value to calculate the exact geometric distance in 2 dimensions. The default option (LongDiff) is the longitudinal difference in 1 dimension. LongDiff does nothing but find the difference in longitude. LongDiff is recommended unless you have a specific reason to use GeoDist (or are just curious).

You can use this program to read your normal aspects and to read relationships you didn't know were there. Conjunctions (0°) will output as 1. Oppositions (180°) will be 2. Trines (120°) will be 3. Squares (90°) will be 4. Sextiles (60°) will be 6. Semisquares (45°) will be 8. Semisextiles (30°) will be 12; Then there are some less regular ones. Sesquiquadrate (135°) will be 1.6 and Quincunx (150°) will be 2.4. Some systems use aspects that are 7-based, 11-based, and various others. This program will tell you what kind of aspect you have by telling you the number base of it. The number base is, after all, the numerological basis for each aspect.