How we calculate your Venus sign

The steps

1. Your date becomes a moment. With a birth time and a time zone, we convert your local time to UTC, including the daylight saving rules in force at your birth place and date. Without them, we treat the date as a window and check the whole window.
2. We find Venus. The astronomy-engine library computes the position of Venus as seen from the center of the Earth at that moment, including the small shift caused by the speed of light.
3. We read the zodiac longitude. The position is converted to ecliptic longitude of date, an angle from 0 to 360 degrees along the path of the Sun. Each sign covers 30 degrees, starting at 0 degrees of Aries.
4. We name the sign and degree. Divide the longitude by 30 for the sign. The remainder is the degree and minute within it.
5. We check for retrograde. We compare Venus's longitude an hour before and an hour after. If it is decreasing, Venus was moving backward at that moment.

The zodiac we use

We use the tropical zodiac, the one used in Western astrology. It is fixed to the seasons: 0 degrees of Aries is where the Sun is at the March equinox. Vedic (Indian) astrology uses the sidereal zodiac, which is fixed to the stars and sits about 24 degrees behind the tropical one today. A sidereal Venus sign is often the sign before the one you see here. This calculator does not give sidereal signs.

How accurate is it?

The astronomy-engine project states that its positions are accurate to within one arcminute, which is a sixtieth of a degree. Venus moves at most about 1.3 degrees a day, so one arcminute is a matter of minutes of Venus's travel. For sign purposes that means:

• With a birth time: the sign is right unless Venus was within a few minutes of a border. If it was within 15 minutes, we tell you to check your time, since birth times are often rounded.
• With only a date: the sign is certain on all but a few days a year. On those days we show both signs and the moment Venus crossed.
• The degree: given to the minute when you give a birth time. Without a time, it is about right to within a degree, because Venus moves up to a degree in a day.

What can go wrong

• The wrong birth time or time zone. This is the most common reason for a different answer from another site, and only on days Venus changes sign.
• Old time zone rules. Your browser's time zone database covers history back many decades, but very old local time rules may be rough.
• Other zodiacs and methods. Sidereal calculators, and sites that use a mean rather than true position, can differ from this tool.
• Dates outside 1900 to 2100. We do not accept them.

The ingress and retrograde tables

The dates on each Venus sign page and in the retrograde guide come from the same library, calculated for 2026 to 2030 and stored on the site. They are in UTC. We will extend them before they run out.

What the meanings are based on

Where Venus was is a fact. What a sign says about you is not. The readings on this site follow common Western astrology, including the traditional ideas of where Venus is at home, exalted, in detriment or in fall. We wrote them ourselves. Controlled studies of astrology have not found that sun signs or other placements predict personality or compatibility. We offer the readings for reflection and fun.

Sources

• Astronomy Engine, an open-source astronomy library (MIT license): github.com/cosinekitty/astronomy
• NASA JPL Horizons, the reference ephemeris service the library's results are checked against: ssd.jpl.nasa.gov/horizons
• MDN Web Docs on Intl.DateTimeFormat, which we use for time zone conversion

Spotted something wrong? Tell us. Ready to try it? Find your Venus sign.