A transit chart calculator that shows its math
Pattern lays the sky today over the sky you were born under. Each contact it finds comes with its orb, the dates it opens, peaks and closes, and the rule that let it count.
Needs your birth date, time and place. Don’t know the time? Pattern leaves out what it can’t support.
| Compared on | Sun-sign horoscope | Pattern transit chart |
|---|---|---|
| Starts from | Your Sun sign, one of 12 | Your birth date, time and place |
| Written for | Everyone born under that sign | Your chart alone |
| Compares | The sky against the sign as a whole | 10 moving bodies against 9 natal points, at 6 angles |
| Close enough | Anywhere in the sign’s 30° | Within 0.72° to 3.00° of exact, set by body and aspect |
| Timing | A day, week or month at a time | Each contact dated: when it opens, is exact and closes |
| Birth time | Not needed | Graded by accuracy; house and angle claims drop out when it can’t support them |
| What you see | Finished text | The reading, with the engine, house system, orb and source behind it |
| Claims | A forecast for the sign | Conditions that open, peak and close. Never a predicted event |
Check one contact
Place a moving body and a natal point anywhere in the zodiac. The page runs the check Pattern runs for every pair in your chart, with the same limits and weights. Nothing you enter leaves this page.
Saturn pressing on your Sun
Identity and direction · Prominent window
- Moving body12.50°Saturn at 12°30′ Aries
- Natal point284.00°Sun at 14°00′ Capricorn
- Separation88.50°The shorter way round the zodiac
- Nearest aspect90°Square
- Orb1.50°Inside the 3.00° limit for Saturn at a square
- Strength0.50Saturn 1.00 × Sun 1.00 × closeness 0.50 × square 1.00
Dates and phase depend on how the planets move, so they come from the full calculation once your birth details are in.
1 · What gets compared
Each day Pattern takes the positions of 10 moving bodies and checks every one against 9 points in your natal chart. A pair counts as a transit when the angle between them is close to one of 6 aspects. Each day is measured at noon in your time zone, or in UTC if you haven’t shared one.
- Moving bodies
- Moon, Sun, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto
- Natal points
- Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Ascendant and Midheaven
| Aspect | Angle | Strength factor |
|---|---|---|
| Conjunction | 0° | 1.00 |
| Sextile | 60° | 0.85 |
| Square | 90° | 1.00 |
| Trine | 120° | 0.85 |
| Quincunx | 150° | 1.00 |
| Opposition | 180° | 1.00 |
2 · How close counts
The orb is how far a pair sits from its aspect’s exact angle. Pattern counts a contact only inside these limits. Slower bodies get a little more room, the Moon less, and the quincunx less than half.
| Moving body | Conjunction, sextile, square, trine and opposition | Quincunx |
|---|---|---|
| Moon | 1.50° | 0.72° |
| Sun, Mercury and Venus | 2.50° | 1.20° |
| Mars, Jupiter, Saturn, Uranus, Neptune and Pluto | 3.00° | 1.44° |
3 · When it opens, peaks and closes
A transit is a window, not a day. Pattern scans backward and forward to find when the orb first falls inside its limit, the closest pass, and when it leaves again. The phase follows the date of the closest pass.
- Opens
- Orb falls to 3.00°
- Closest pass
- Smallest orb
- Closes
- Orb back past 3.00°
Building
The aspect is tightening toward its closest pass.
Exact
The aspect is at its closest point today.
Fading
The closest pass has happened; the window is easing off.
Jupiter, Saturn, Uranus, Neptune and Pluto can turn retrograde and cross the same point again. When the day’s leading contact comes from one of them and your birth time is known, Pattern numbers each crossing (contact 2 of 3, say) and marks the stretch between crossings.
4 · How contacts are ranked
Strength decides which contact leads your day. Slow movers and your Sun, Moon and angles weigh most, and a contact grows stronger as its orb closes.
strength = body weight × point weight × closeness × aspect factor
closeness = 1 − orb ÷ limit
aspect factor = 1.00 for conjunction, square, quincunx and opposition; 0.85 for sextile and trine
Ascendant and Midheaven × 0.60 when the birth time is only known to the hour
| Moving body | Weight |
|---|---|
| Moon | 0.15 |
| Sun | 0.50 |
| Mercury | 0.35 |
| Venus | 0.40 |
| Mars | 0.60 |
| Jupiter | 0.85 |
| Saturn | 1.00 |
| Uranus | 0.95 |
| Neptune | 0.90 |
| Pluto | 1.00 |
| Natal point | Area | Weight |
|---|---|---|
| Sun | Identity and direction | 1.00 |
| Moon | Inner life and rest | 0.95 |
| Mercury | Work and output | 0.60 |
| Venus | Relationships and affection | 0.70 |
| Mars | Work and output | 0.70 |
| Jupiter | Structure and commitments | 0.55 |
| Saturn | Structure and commitments | 0.60 |
| Ascendant | Identity and direction | 0.90 |
| Midheaven | Work and output | 0.85 |
| Label | Strength |
|---|---|
| Major | 0.70 or more |
| Prominent | 0.40 to under 0.70 |
| Background | Under 0.40 |
5 · Birth time and sources
Unknown or approximate birth times are normal. Pattern grades what the time can support and suppresses the claims that depend on it rather than softening them.
| Birth time | House claims | Ascendant and Midheaven contacts |
|---|---|---|
| Recorded to the minute | Supported | Full weight |
| Within about 15 minutes | Supported | Full weight |
| Within about an hour | Suppressed | Weighted ×0.60 |
| Unknown — noon assumed | Suppressed | Left out |
- Your natal chart
- Positions, Placidus houses and angles come from a Swiss Ephemeris service. If it is unavailable, an in-app approximate engine fills in and the reading says its precision is degraded.
- Today’s geometry
- Transit positions and orbs come from the in-app analytical engine, labelled approximate on every reading.
- Exact dates for slow planets
- When the day’s leading contact comes from Jupiter to Pluto and your birth time is known, its dates come from the Swiss Ephemeris service, checked at your recorded time and at both ends of its uncertainty. Pattern names an exact day only when all three agree; otherwise the in-app dates stand.
- Source code
- The ephemeris service’s calculation source code, including its pinned ephemeris files, is published under the GNU Affero General Public License.
Questions
What is a transit chart?
A transit chart lays the planets’ current positions over your natal chart, the sky at the time and place you were born. A transit is a moving planet at a set angle, called an aspect, to one of your natal points.
When does Pattern count a transit?
When a moving body is within its orb limit of one of 6 aspects to a natal point. The limit is 1.50° for Moon; 2.50° for Sun, Mercury and Venus; 3.00° for Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. The 150° quincunx gets a narrower limit.
Do I need an exact birth time?
No. Pattern asks how accurate the time is. Within about 15 minutes, houses and angles are used. Within about an hour, house claims are suppressed and Ascendant and Midheaven contacts count for less. With an unknown time, Pattern assumes noon and leaves house and angle claims out. Contacts to the Sun, Moon and planets are still calculated, though the natal Moon moves about 13° a day, so its position can be several degrees off.
Which house system and ephemeris does Pattern use?
Natal positions, Placidus houses and angles come from a Swiss Ephemeris service. If it is unavailable, an in-app approximate engine fills in and the reading says its precision is degraded. Day-to-day transit geometry comes from the in-app engine and is labelled approximate. When the day’s leading contact comes from Jupiter, Saturn, Uranus, Neptune or Pluto, its exact dates come from the Swiss Ephemeris service.
Does Pattern predict what will happen?
No. A transit is described as a condition with a start, a peak and an end. Pattern never states what will happen.
Is the reading written by AI?
The calculation never is. The wording can be: Google Gemini, through the Lovable AI gateway, may write the day’s reading from the calculated facts and Pattern’s published interpretations, and has to cite them. Raw birth details are never sent to it. If a draft fails Pattern’s checks, the template wording is used instead, and each reading shows which one you got.
What happens to my birth details?
They are stored encrypted with your account and used to calculate your chart. You can export or erase them from Context & privacy.
Calculate your own transits
Add your birth date, time and place. Pattern calculates your chart, lists every active contact with its window, and writes one reading a day from the strongest.
Needs your birth date, time and place. Don’t know the time? Pattern leaves out what it can’t support.