Astrology Birth Chart Calculator

Most astrology sites give you a sun sign and call it a day. That’s roughly 8% of the picture. A full natal chart — also called a birth chart — maps where every planet sat at the exact moment you were born, relative to the horizon and the twelve zodiac houses. This birth chart calculator builds that map from three inputs: your date of birth, time of birth, and geographic coordinates. The result is a complete wheel with planetary positions, house placements, and the geometric relationships (aspects) between planets.

The chart you get here includes ten celestial bodies: Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Each one is placed in one of the twelve zodiac signs and one of the twelve houses. The Ascendant (the sign rising on the eastern horizon at your birth) anchors the entire wheel, and the Midheaven marks the highest point. Together, these form the skeleton of astrological interpretation.

Where Do the Numbers Come From?

Planetary positions are calculated using the Meeus method — a set of simplified astronomical algorithms published by Jean Meeus that approximate where each body falls along the ecliptic for any date between 1900 and 2100. The calculator converts your local birth time to Universal Time, computes a Julian Day Number, then derives each planet’s ecliptic longitude from orbital elements and perturbation corrections. Accuracy is within one to two degrees, which is sufficient for sign and house placement.

House cusps depend on the system you choose. Three options are available: Placidus, which divides the sky by time-based semi-arcs and is the most widely used system in Western astrology; Whole Sign, which assigns one complete sign per house starting from the Ascendant; and Equal House, which spaces each cusp exactly thirty degrees apart from the Ascendant. Switching between systems shifts where planets land in the house grid, sometimes changing the interpretation significantly.

The city search includes over 120 locations worldwide, each with pre-set latitude, longitude, and timezone offset. If your birthplace isn’t listed, enter coordinates manually — the timezone is editable as well. For births where the exact time is unknown, enable the Unknown Time checkbox. The calculator defaults to noon, but a warning appears noting that house positions and the Moon’s degree may shift by several degrees depending on the actual birth hour.

How Do You Read the Four Result Tabs?

After generating, the results split across four tabs. The first shows the natal wheel — an SVG diagram with the zodiac ring, house divisions, planet markers, and colored aspect lines connecting them. Cardinal axes (Ascendant, Descendant, MC, IC) are drawn with heavier strokes.

The Positions tab lists every planet with its zodiac sign, degree, and house number. Ascendant and Midheaven appear at the bottom of the table. The Aspects tab presents a grid where each cell marks the angular relationship between two planets. Conjunctions, sextiles, squares, trines, and oppositions each get a distinct label and color — blue for harmonious aspects, red for tense ones.

The Analysis tab breaks down your chart by element and modality. It counts how many planets fall in Fire, Earth, Air, and Water signs, then does the same for Cardinal, Fixed, and Mutable. The dominant element and dominant modality combine into a Signature Sign — a single sign that summarizes the chart’s overall energetic emphasis. If your chart is heavy in Earth and Cardinal energy, for example, the Signature Sign is Capricorn.

The chart can be downloaded as a PNG image, printed directly, or the positions data can be copied as formatted text. Previous charts are stored locally — up to five — so returning to compare different birth data takes one click instead of re-entering everything.