Part of Fortune in Astrology: Meaning, Formula and How to Find It

← Back to Birth Charts

The Part of Fortune is a calculated point in the birth chart. It is not a planet or any other body in the sky: it is a zodiac degree found by measuring the distance between the Sun and the Moon and then counting that same distance from the Ascendant. Because it is tied to the Ascendant, its calculated position is highly birth-time-sensitive, and it can only be found for a chart with a reliable birth time.

This page explains what a part is, sets out the formula used on these pages and why it depends on whether you were born by day or by night, walks through the calculation step by step with two worked charts, and ends with how astrologers read the result.

This is a technique explained here, not a feature of the calculator. The free birth chart does not calculate or display the Part of Fortune, and it does not mark a chart as a day or night chart. The worked figures below are offline educational arithmetic: the Sun, Moon, Ascendant and house cusp values come from the same calculation code that draws the free chart, and the formula was applied to them by hand. Nothing here is a hidden setting of the chart. The Astrologist chat is not given a Part of Fortune for your chart and is not a lot or sect calculator.

What a part, or lot, is

In Hellenistic astrology, a lot (Greek kleros) is a point built from three chart factors: the distance from one factor to a second is measured, and that distance is then laid off from a third, usually the Ascendant. Later Latin authors called these points partes, which is where "part" comes from, and they are sometimes called Arabic parts after their wide use in medieval astrology. The Part of Fortune, also called the Lot of Fortune, is the best known of them.

A part is a mathematical point, so it has no motion of its own, no retrograde and no light. It has a sign and a degree like any other position, and, once the house cusps are known, a house. Its sign also gives it a ruling planet.

Fortune uses the two lights. Its companion, the Lot of Spirit, is another lot formed from the same two lights with their relationship reversed; this page does not cover it further.

The formula used on these pages

The convention used on these pages is the one usually given for traditional (Hellenistic) astrology, where the formula depends on the sect of the chart:

• Day chart: Part of Fortune = Ascendant + Moon − Sun
• Night chart: Part of Fortune = Ascendant + Sun − Moon

All three values are written as longitudes from 0° Aries (0° to just under 360°). If the result is negative, add 360°; if it is 360° or more, subtract 360°. That step is called taking the result modulo 360.

Some astrologers and some chart software use the day formula for every chart, by day and by night. A source that does so can legitimately show a different Fortune position for a night birth than these pages do. It is a difference of convention, not a calculation error on either side, so when you compare sources, check which formula each one uses.

What the formula measures. Under the day formula, Fortune sits exactly as far past the Ascendant, counting forward in zodiac order, as the Moon sits past the Sun. That Moon minus Sun distance is the directed elongation that also sets your natal Moon phase, explained on natal Moon phases explained and worked out step by step on how to find your natal Moon phase. The night formula counts the same distance the other way, backwards from the Ascendant.

Two consequences follow from that. For a birth at a New Moon, when the Sun and Moon are together, both formulas put Fortune on the Ascendant degree; for a birth at a Full Moon, both put it on the Descendant. The two formulas give their most different answers when the Moon is near a quarter, about 90° from the Sun.

First: is it a day chart or a night chart?

Because the formula changes with sect, you need to know which applies before you calculate. A day chart has the Sun above the horizon, the line from the Ascendant to the Descendant; a night chart has the Sun below it. On the free chart's wheel the Ascendant is on the left and the Descendant on the right, so a Sun tick clearly in the upper half is a day birth and one clearly in the lower half a night birth.

When the Sun sits very close to that line, the answer can depend on a few minutes of birth time. Day and night charts explains the rule, the house-number shortcut and its limits, and what to do near the horizon. If the sect is uncertain, the Part of Fortune is uncertain too, because the two formulas give different points.

How to find your Part of Fortune, step by step

The free chart gives you part of what you need, but not all of it. Its planet table prints the Sun and Moon degrees, but it does not print the Ascendant's degree as a number, and it does not print a table of house cusp degrees. On its own, the free chart is therefore not enough for a reproducible manual Fortune degree.

1. Confirm the chart on the free chart. Enter your birth date, exact time and place on the free birth chart. Note the Rising sign and the house system named under the wheel (Placidus, or Equal houses for births more than 66° north or south), and check from the wheel whether the Sun is above or below the horizon.
2. Take the Sun and Moon from the planet table. Convert each to a longitude by adding the start of its sign: Aries 0°, Taurus 30°, Gemini 60°, Cancer 90°, Leo 120°, Virgo 150°, Libra 180°, Scorpio 210°, Sagittarius 240°, Capricorn 270°, Aquarius 300°, Pisces 330°. Minutes become decimals by dividing by 60.
3. Get a precise Tropical Ascendant degree from a calculation source that prints it, using the same birth date, time, place, time zone and Tropical zodiac. Its Ascendant should fall in the Rising sign the free chart shows. If it does not, the birth data or settings differ, and the result will not describe the same chart.
4. Apply the formula for your sect and take the result modulo 360. Then convert back to a sign and degree by subtracting the start of the sign the result falls in.
5. Place it in a house using exact cusp degrees from a source that prints all twelve, with the same settings. How to find your house cusps covers which settings to match and the rule for placing a degree between two cusps.

Fortune's sign and degree are the same in any house system; only its house number can change. The worked charts below use the site's default Placidus cusps. Another system can put the same degree in a different house, as house systems explained describes.

Worked example: Ruben, a day chart

Ruben is a fictional example used in several Astrologist.com guides: London (51.5074° N, 0.1278° W), 5 January 1993, 12:00 local time, which in a London winter is also 12:00 UT. The time is treated as a recorded birth time. His chart was recalculated with the routines that draw the free chart, and the longitudes below are the values that code returns, to 0.01°.

Sect. The Sun is in the 10th house, high in the upper half of the wheel, so this is clearly a day chart.

Day formula. 33.77 + 65.73 − 285.17 = −185.67. Add 360 to get 174.33°. That falls in Virgo, which starts at 150°: 174.33 − 150 = 24.33, so the Part of Fortune is at 24°19' Virgo (minutes cut off, as on the free chart's planet table). As a check, 174.33 − 33.77 = 140.56: Fortune is 140°33' past the Ascendant, the same as the Moon's 140°33' lead over the Sun.

House. Ruben's Placidus 6th cusp is at 4°47' Virgo (154.79°) and his 7th cusp at 3°46' Scorpio (213.77°). Fortune at 174.33° is 19.54° past the 6th cusp and well short of the 7th, so it is in his 6th house.

Ruler. Virgo is ruled by Mercury in both the modern and the traditional schemes. Ruben's Mercury is at 4°25' Capricorn in his Placidus 9th house.

What the night formula would give. Only to show why the convention matters: if these same three positions belonged to a night chart, the night formula would give 33.77 + 285.17 − 65.73 = 253.21°, which is 13°12' Sagittarius in his 8th house. Ruben's chart is a day chart, so under the convention used on these pages that is not a second Fortune for him. It is the position a source using the other formula choice would show for a night birth with these inputs.

Worked example: Noor, a night chart

Noor is a fictional example made for this page: Amsterdam (52.3676° N, 4.9041° E), 2 December 1992, 21:30 local winter time (20:30 UT), treated as a recorded birth time and calculated with the same routines.

Sect. The Sun is in the 5th house, in the lower half of the wheel, so this is a night chart.

Night formula. 134.45 + 250.93 − 347.37 = 38.01°. That is in Taurus, which starts at 30°, so the Part of Fortune is at 8°00' Taurus.

House. Noor's Placidus 10th cusp, her Midheaven, is at 26°14' Aries (26.24°) and her 11th cusp at 6°22' Gemini (66.37°). Fortune at 38.01° lies between them, in her 10th house.

Ruler. Taurus is ruled by Venus in both schemes. Noor's Venus is at 23°03' Capricorn in her 6th house.

For comparison only, the day formula on the same inputs would give 134.45 + 347.37 − 250.93 = 230.89°, or 20°53' Scorpio in her 4th house: a different sign, a different house and a different ruler from the night result. A source that applies the day formula to every chart would show that position for Noor.

Reading the Part of Fortune

Astrologers read Fortune through the same three layers as any chart factor, though as a point it has no planetary nature of its own:

• Its sign suggests the style or manner in which the themes of the point tend to show up. Ruben's Virgo Fortune might be read through care, practical skill and attention to detail.
• Its house shows the area of life where those themes tend to be sought. A 6th-house Fortune, like Ruben's, points to daily routines, work and service; a 10th-house Fortune, like Noor's, to public role and visible work. House meanings covers all twelve areas.
• Its ruler links the point to the rest of the chart. Read the planet that rules Fortune's sign by its own sign and house, as with any house ruler. For Ruben, Mercury in the 9th ties his Fortune to study and belief; for Noor, Venus in the 6th ties hers back to daily work.

Modern and traditional rulers. The site uses modern rulers first and also names the traditional ones. For Fortune in Scorpio, Aquarius or Pisces, the modern ruler is Pluto, Uranus or Neptune and the traditional ruler Mars, Saturn or Jupiter. Keep the two layers apart: the historical Fortune technique was built on the seven visible bodies only, so it used the traditional ruler. Reading Pluto, Uranus or Neptune as Fortune's ruler is part of the site's modern interpretive layer, not of the ancient doctrine. Modern and traditional rulers explains the two schemes.

Historical meanings. Traditional authors associated the Lot of Fortune with the body and with material circumstances. That is historical doctrine, reported here so the term is recognisable. The modern reading used on these pages stays non-medical and non-deterministic: an astrologer might ask where practical circumstances, resources and support tend to feel more workable, or where a person may feel most physically at home in daily life.

What Fortune does not mean. It is not a lucky spot, a promise of money or success, or a forecast of events, and it says nothing about health, illness or how long anyone lives. A Fortune in the 2nd house does not mean wealth, and one in the 12th does not mean misfortune. Nor does a sign rule a house: Fortune in Taurus is not the same thing as Fortune in the 2nd house, because signs and houses are separate parts of the chart.

Why it needs a reliable birth time

Fortune is built on the Ascendant, so its calculated degree changes rapidly as the birth time changes; the Sun-Moon term changes too, and the formula itself switches if the tested time crosses the sect boundary. In Noor's chart the calculated degree shifts by about 1°40' for every ten minutes of assumed birth time: from 29°39' Aries at 20:40 to 17°57' Taurus at 22:30. In Ruben's chart, a birth time known only as "between 11:00 and 13:00" leaves Fortune anywhere from 19°51' Leo to 20°36' Libra, across three signs. Ascendant degree vs Rising sign and how accurate a birth time needs to be explain that sensitivity.

Without a reliable birth time there is no Ascendant, so there is no Part of Fortune. The free chart leaves the Rising sign and houses out of an unknown-time chart, and it calculates the planets for local noon only as an internal reference; that noon reference is never a birth time and must not be used to calculate Fortune. A chart without a birth time explains what remains usable.

For births more than 66° north or south, the free chart uses Equal houses from the Ascendant, and polar charts carry a known caution about how the Ascendant is selected. Do not treat a Fortune position built from an unverified polar Ascendant as reliable; chart angles at high latitudes sets out the check.

Try it with your own chart

Start with your free birth chart for the birth data, Rising sign, Sun and Moon, then follow the five steps above with a source that prints the Ascendant degree and the cusps. The methodology page explains the site's zodiac, house and rulership choices. You can ask the Astrologist about the planets, signs and houses of the chart calculated on the site. To see how the Sun and Moon fit with your Rising sign more generally, read Sun, Moon and Rising explained.

Related articles

• Day and Night Charts: What Sect Means in Astrology
• Natal Moon Phases Explained
• Ascendant Degree vs Rising Sign
• How to Find Your House Cusps
• House Rulers in Astrology
• Modern and Traditional Rulers