How the life chart is calculated

What the life chart shows

The life chart plots one candle for every year of life from age 1 to age 100. Each year runs from one birthday to the next. A green candle means the year scores higher than the one before it; a red candle means it scores lower. The score is a relative index between 0 and 100, and it summarises how supportive or demanding that year is by the standards of traditional transit astrology.

Three inputs drive the chart: your birth date, and three Major Arcana cards that you choose or draw. Your Sun sign is worked out from your birth date, so you do not need to know it.

Step 1: your birth sky

We calculate the geocentric ecliptic longitude of the Sun, Jupiter, Saturn and Uranus on your birth date at 12:00 UTC. We use the Keplerian orbital elements published by NASA’s Jet Propulsion Laboratory (E. M. Standish, “Approximate Positions of the Major Planets”), solve Kepler’s equation for each planet and for the Earth, and convert the result to the tropical zodiac by correcting for precession.

We checked these positions against a high-precision ephemeris for every month from 1900 to 2130. The largest error was 0.02° for the Sun, 0.2° for Jupiter, 0.5° for Saturn and 0.2° for Uranus, far smaller than the orbs used below. The North Node uses the standard mean-node formula from Jean Meeus’s Astronomical Algorithms.

Because we do not ask for your birth time or time zone, the Sun’s position can be off by up to about one degree. If your Sun is within 1.1° of a sign boundary, the calculator tells you that your sign may depend on your birth time.

Step 2: transits, year by year

For each year of life we sample the sky every ten days (36 times a year) and check whether a moving planet forms an aspect to a point in your birth chart. An aspect counts when the angle is within the orb shown below. Its strength runs from 1 when the aspect is exact down to 0 at the edge of the orb, and we keep the strongest moment of the year.

The effect is the number of points the aspect adds to or subtracts from the year’s score at full strength. The wick weight measures how much the aspect widens that year’s candle (see step 4). Hard aspects from Jupiter are scored as mildly positive but with a high wick weight, because tradition reads them as growth through tension.

Step 3: three life phases and your tarot cards

Saturn takes about 29.5 years to go round the zodiac, so it returns to its birth position around ages 29, 58 and 88. Astrologers have long treated the first two Saturn returns as the thresholds of adulthood and of the elder years. We use your actual Saturn return ages to divide life into three phases: formative years (from age 1 to your first Saturn return), building years (up to your second Saturn return) and harvest years (from then on).

Your first card governs the formative years, your second the building years and your third the harvest years. Each of the 22 Major Arcana cards has two fixed values taken from its traditional upright meaning: a tone between −1 (heavy) and +1 (bright), and a volatility between 0 (calm) and 1 (upheaval). For example, The Sun has tone +0.9 and volatility 0.3, while The Tower has tone −0.7 and volatility 1.0.

A phase’s baseline score is 50 + 15 × the card’s tone. Around each Saturn return the baseline blends smoothly from one card to the next over four years, so there is no artificial cliff. We look for the first two Saturn returns between ages 26 and 32 and between ages 55 and 62; if none were found, ages 29 and 59 would be used, but for every birth date from 1900 to today the returns are found. The table below lists the values of all 22 cards.

Step 4: from scores to candles

A year’s score is its phase baseline plus the effect of every aspect active that year, multiplied by its strength, kept between 8 and 96. Each candle opens at the previous year’s score and closes at this year’s score. The wicks show how turbulent the year is: above and below the candle body, each wick is 2 + 5 × the phase card’s volatility + 0.6 × the sum of (wick weight × strength) over that year’s aspects, rounded and kept between 0 and 100.

The written note for each year names the one or two aspects with the largest effect on the score, among those with a strength of at least 0.3. Years without such an aspect are described through the phase card.

Step 5: the written report

Each section of the report pairs the traditional description of your Sun sign and cards with the ages that matter for that theme in your chart. Section scores out of 10 are the average yearly score over the ages listed below, rescaled as 5 + (average − 50) ÷ 6, adjusted by half the tone of the relevant card and kept between 1 and 10. The tarot score is 5 + 4 × the average tone of your three cards. Wealth and health are described without a score, so that they are not mistaken for financial or medical ratings.

The age lists in each section only include years in which a relevant aspect reaches a strength of at least 0.7, and an age that appears among the demanding years is left out of the supportive ones. The most supportive and most demanding decades are the ten-year stretches from age 18 onward with the highest and the lowest average score.

What the chart is not

The life chart is a structured way to look at traditional astrological cycles. It is not a scientific prediction, and nothing in it is fate. Astrology and tarot have no demonstrated power to forecast events. Please do not base medical, financial, legal or other important decisions on it.

The chart also leaves out a great deal that a full natal reading would include, such as the Moon, the personal planets, houses and the Ascendant, all of which need an exact birth time and place. We chose a smaller set of slow cycles that can be calculated reliably from the birth date alone.

Why we do not use AI to write your chart

An AI language model would write a different reading every time and could not explain where its numbers come from. A fixed method is reproducible, transparent and private, because it runs entirely in your browser. If you would like a longer written interpretation, the results page offers an optional prompt that you can copy into an AI assistant of your choice, together with your calculated chart.

Sources

• E. M. Standish, “Keplerian Elements for Approximate Positions of the Major Planets”, NASA Jet Propulsion Laboratory Solar System Dynamics.
• Jean Meeus, Astronomical Algorithms, 2nd edition (Willmann-Bell, 1998): mean lunar node and precession.
• Traditional meanings of transits, Saturn and Jupiter returns and the Uranus opposition, as described in the Western astrological literature.
• Upright meanings of the Major Arcana in the Rider–Waite–Smith tarot tradition. See our tarot guide.