Free Lot of Basis Calculator

The Lot of Basis, also called the Lot of Foundation, is a calculated point in Hellenistic astrology that marks the foundation your life rests on: the body, the breath, and your physical footing in the world. It is built from the shortest distance between your Lot of Fortune and your Lot of Spirit, then measured out from the Ascendant.

The Greek word basis means a pedestal, the base a statue stands on. That is the whole idea. Fortune shows what the world hands you and Spirit shows what you do with it, and Basis is the ground both of them stand on.

Rhetorius put it plainly. He called Basis “an accessory cause of life and breath,” a point that “signifies bodily things and dwelling abroad.” Later astrologers named it the security of the Ascendant, the part of the chart that speaks to physical well-being and the stability of the life itself. Vettius Valens grouped it with Fortune, Spirit, and the Lot of Exaltation when he judged rank and standing in the world.

What makes Basis unusual among the lots is that it has no planet in its formula. Most lots measure an arc between two planets. Basis measures the arc between two other lots, both of which are themselves derived. It is a point built on points, which is fitting for something meant to describe a foundation.

The rule this calculator uses is short. Find your Lot of Fortune and your Lot of Spirit, measure the shorter arc between them (the gap that is 180 degrees or less), and add that arc to your Ascendant, counting forward in zodiacal order. Where you land is the Lot of Basis.

Valens stated it by sect, but both routes reach the same place, because the shorter arc is always the one that lands below the horizon. For an example: Fortune at 20° Scorpio and Spirit at 20° Sagittarius are 30 degrees apart. With an Ascendant of 15° Cancer, you add 30 degrees and arrive at 15° Leo, the second whole sign house. That degree is the Lot of Basis.

The formula needs your exact birth time, down to the minute. Basis is measured from the Ascendant, which advances roughly one degree every four minutes, so a small error can shift the point into a different degree or across a sign boundary. If your time is uncertain, run a birth time rectification before treating the result as settled.

Read Basis when you want the through-line of someone's physical life, the steady thing underneath the noise. Fortune is the body and circumstance, the events that arrive whether you asked for them or not. Spirit is mind and will, the part of you that chooses and acts. Basis sits where those two meet and turns them into a footing, which is why the old sources tie it to breath and to the security of the living person.

The ruler of the sign Basis falls in carries much of the weight. A Basis whose ruler is strong by sign and well placed by house tends to describe a life with solid ground under it, a baseline of physical security that holds even when Fortune turns. A Basis whose ruler is weak or badly placed points to a foundation that needs tending. Hold it as a pattern rather than a verdict. The chart shows the terrain you are working with and leaves the destination open.

Basis is never really a stranger in the chart, because it is built entirely from the two lots you likely already know. It is the shorter arc between Fortune and Spirit, so it always sits between them and always falls in the lower half of the chart.

There is a historical wrinkle worth naming. In the Valens tradition, the Lot of Eros and the Lot of Necessity were computed from this same Fortune-Spirit pair, so Basis coincided with whichever of the two fell below the horizon. This calculator, like the rest of the site, computes Eros from Venus and Necessity from Mercury (the later Paulus formulas), so on your chart those points will not line up with Basis numerically. Treat the connection as conceptual rather than a numeric identity. The Arabic Parts calculator plots the wider system at once.

Because Basis always falls below the horizon, it lands in one of the first six houses counted from your rising sign. The house tells you what your foundation is built on. The 1st makes it the self and the body; the 2nd, livelihood and sustenance; the 3rd, daily contact and movement; the 4th, the most literal foundation of home, land, and ancestry; the 5th, children and creative life; the 6th, work, health, and the body's limits.

Your calculated result above shows the specific house your Basis occupies and reads it in full. Then check the ruler of that house and the planets near the lot before drawing firm conclusions, since the foundation is described by its whole setting rather than by the degree alone.

The two terms get tangled in older sources, so a clarification helps. Some material calls a wealth point the “Lot of Substance,” computed from Jupiter and Mars, and reads it for money and possessions. That is a different point from the one on this page. Basis is the foundation of the living person, the body and its security. The size of the bank balance is a separate question. If money is what you are after, you want the wealth lot, which uses a different formula. Basis answers a different question entirely: what is the ground this life stands on.