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Part of Fortune calculator
The Part of Fortune is a calculated point in your birth chart, not a planet. It sits as far from your Ascendant as the Moon is from the Sun. For a day birth the formula is Ascendant + Moon − Sun; for a night birth, Ascendant + Sun − Moon. Astrologers read its sign and house as where ease, bodily wellbeing and material luck tend to come to you. Because it moves with the Ascendant, you need your birth time.
Your Part of Fortune with the right formula for a day or night birth, its house, and where its ruling planet sits.
How it is calculated
Your Sun, Moon, Ascendant and house cusps come from the Shymea engine, which computes positions with Skyfield on NASA JPL's DE442 ephemeris in the tropical zodiac. The engine checks whether the Sun was above or below the horizon at your birth (a day or night chart) and applies the matching formula. Many free calculators use the day formula for everyone, so a night birth can get a different answer here.
The house is the Placidus house the point falls in. The ruler shown is the traditional ruler of the sign the Part of Fortune is in, the planet that older astrologers read as managing it, together with that planet's own sign and house from the same chart.
The Part of Spirit is shown too. It uses the opposite formula and is traditionally read as its pair: Fortune for the body and circumstances, Spirit for intention and action.
Common questions
- How is the Part of Fortune calculated?
- Ascendant + Moon − Sun for a day birth (Sun above the horizon) and Ascendant + Sun − Moon for a night birth. In both cases the point sits the same distance from the Ascendant as the Moon is from the Sun.
- Can I find my Part of Fortune without a birth time?
- Not reliably. The point moves with the Ascendant, about 1° for every 4 minutes of birth time on average, so a guessed time can move it a whole sign. The calculator asks for a time for that reason.
- Why is my Part of Fortune different on another site?
- Usually because that site uses the day formula for every chart. If you were born at night, the reversed formula gives a different point. House systems can also differ: this page uses Placidus.
- What does the house of the Part of Fortune mean?
- Astrologers read the house as the area of life where things come more easily and where material luck tends to show up, for example the 10th for career or the 2nd for earnings. It is a theme to notice, not a promise.
Go deeper
More free tools
Your chart
Planets and points
Returns and cycles
Sun, Moon, Ascendant, house cusps and the Part of Fortune itself are computed by the Shymea engine (Skyfield on NASA JPL DE442, tropical zodiac, Placidus houses). The engine uses Ascendant + Moon − Sun when the Sun is above the horizon and Ascendant + Sun − Moon when it is below. Rulers are traditional. Readings are educational, not medical, legal or financial advice. See the editorial policy.
