Free astrology calculators: birth chart, synastry, transits

These calculators cast charts; they do not read them. Each one takes a birth date, a time and a city, resolves the historical time zone that birth was recorded in, computes where the planets and the angles stood, and hands the chart back with its placements, houses and aspects. What the chart means is a reading, and a reading is a person's work. No account, and no birth detail is ever kept or written into a link.

Which calculator answers which question

• What is my birth chart? The birth chart calculator draws the wheel with every planet, house and aspect, and answers properly when the birth time is unknown.
• How do our two charts meet? The synastry calculator ranks every contact between two charts by how close it is, and folds them into a composite or a Davison chart on request.
• What is the sky doing to my chart right now? The transit chart calculator places today's planets in your houses and lists the exact dates ahead.
• When is my solar return, and where should I spend it? The solar return calculator finds the instant to the minute and compares up to five places side by side.
• Which planets are retrograde this year? The retrograde calendar lists every period, with dates and durations, as a table or a subscribable calendar.

What makes two charts of the same person disagree

Almost always one of three things: the house system, the time zone applied to the birth time, or a site that silently assumed noon because the time was left out. Every calculator here states the house system it used and takes the zone from the city, so the two can be compared honestly. All of them are tropical, which is why a Sun sign here differs from a Vedic chart by about twenty-four degrees.