Transit calculator
Transit Calculator: What the Sky Is Doing to Your Chart
Your birth chart stopped moving the day you were born. The sky did not. This tool puts the two side by side: where each planet is at this moment, which of your houses it is crossing, and the exact angles between the two.
Your birth data
Your birth details are used only to calculate this chart. They are not saved.
How close counts
An aspect is almost never exact, so astrologers allow a margin around it, called the orb. There is no agreed number. Some count only angles within a degree, most work with about three, others stretch to five. Choose the one you read by; every result repeats which orb produced it.
The calculation runs for the moment you press the button, to the second, and the result carries that timestamp so you can check it against any ephemeris.
Still needed: Birth Date · Birth Time · Birth City
What a transit actually is
A transit is a measurement. Take the position a planet holds in the sky at this moment, take a position from your birth chart, and measure the angle between them. When that angle lands near 0, 60, 90, 120, 150 or 180 degrees, astrologers call it an aspect and give it a name. Nothing has been predicted; something has been measured. The planets are really there and the angle is really that size, which is why two people with the same birth data get the same list. What the tradition adds is meaning, and meaning is where the disagreement lives. Two astrologers reading the same Saturn square will often say different things about it, and neither of them is reading a different sky.
What this does not tell you
It does not tell you what will happen, or when, or to whom. Transits are shared: everyone born within a few days of you is under the same outer-planet transits right now, and the days of their lives are not the same. It also does not rank your transits by importance. The orb tells you how precise an angle is, not how much it matters, and a wide angle to a planet that runs your chart can be more relevant than an exact one to a planet that does not. Anyone who hands you a schedule of events from this data has added something that is not in it.
Orbs, the number astrologers argue about
The orb is the tolerance around an exact angle. It exists because planets move: an angle passes through exact rather than sitting on it, so a rule is needed for when it starts counting and when it stops. Transit orbs run tighter than the ones used inside a birth chart, and the reason is practical. A birth chart is one frozen moment, so a wide angle is still a permanent feature of it. A transit is a passage, and a wide orb turns a passage into a season: transiting Mars within 8 degrees of your Sun covers most of a month. That is why the tool defaults to 3 degrees and lets you go tighter or wider, rather than picking a number and calling it the standard.
Applying and separating
An applying aspect is one where the transiting planet is still closing in: the orb is shrinking and the angle will be exact at some point ahead. A separating aspect has already been exact and is opening again. Most traditions read applying angles as the more active half, on the reasonable grounds that the event they describe is still in front of you rather than behind. The arrow in the results marks which is which. Because a retrograde planet reverses direction, the same aspect can apply, separate and apply again over several months, which is why a transit is usually described as a window rather than a date.
Which bodies are counted
The ten planets, Chiron, and the mean lunar node transit. Their angles are measured against every planet in your chart plus your Ascendant and Midheaven, which is why a known birth time roughly doubles what this page can say. The Part of Fortune and the Vertex are left out of both sides on purpose. They are computed from the angles and the lights rather than tracked by an ephemeris, so an aspect to them repeats information the chart has already given you, dressed up as a new fact.
Questions about transits
How often should I check my transits?
The Moon changes sign every two and a half days and makes several angles a day, so it will look different every morning. Everything from Jupiter outwards moves slowly enough that a monthly look is plenty. If a page like this pulls you back several times a day, it is answering an anxiety rather than a question.
Why does this show different transits than another site?
Almost always the orb. A site that allows 8 degrees will list two or three times as many angles as one that allows 3. Check the orb column before assuming the positions disagree; the planets are the same in every ephemeris to within a fraction of a minute of arc.
Do I need my birth time?
Not for most of the planetary angles. The exception is the Moon: it moves about 13 degrees a day, so an unknown time leaves it six or seven degrees off, enough to change which aspects appear at all. The other bodies carry up to half a degree of the same doubt, Mercury as much as a degree, which is worth remembering when the printed orb is in arcminutes. You do need the time for houses and for angles to the Ascendant and Midheaven, since those depend on the exact minute the sky was rotating past your birthplace.
Is a square transit bad news?
It is an angle of ninety degrees. The tradition reads squares as friction and trines as ease, and both readings are conventions rather than measurements. Plenty of people describe their most useful years under squares and their least memorable under trines.
What is the difference between a transit and a progression?
A transit is the real sky today. A progression is a symbolic clock, where the sky of the days after your birth is read as the years of your life. They run at completely different speeds and are usually read together.
The conventions this chart uses
None of these are facts of the sky. Each is a choice astrologers disagree on, so we list ours — a difference from another site can then be traced to its rule instead of blamed on the stars.
- Tropical zodiac
- Signs are tropical, anchored to the March equinox, not to the constellations. Sidereal (Vedic) astrology counts from the stars instead, which currently shifts every position by about 24 degrees — the most common reason two sites disagree about a sign.
- Placidus houses
- Houses are Placidus, the most widely used modern system. Whole-sign or Koch redraw the boundaries: they move planets between houses, never between signs. Beyond the polar circles Placidus is undefined, and we then show the chart without houses rather than guess.
- Mean lunar nodes
- The lunar nodes are mean (averaged). The "true" node oscillates around the mean by up to about two degrees — measured, at most 1°59' across two centuries.
- Mean Lilith
- Black Moon Lilith is the mean lunar apogee. The "true" (osculating) variant can sit up to about thirty degrees away — often a different sign, and the single biggest source of Lilith disagreements.
- Aspect orbs
- Natal orbs: conjunction and opposition 8°, square and trine 7°, sextile 5°, quincunx 3°. Toward the Ascendant and Midheaven the orbs tighten, and the quincunx is not counted there at all. A site with wider orbs lists more aspects, not different planets.
- Sect
- The Part of Fortune follows sect: a day birth (Sun above the horizon) uses Ascendant + Moon − Sun, a night birth the reverse. For night births, calculators that apply the day formula to everyone place it in a different sign roughly nine times out of ten.