What a chart pattern is
A chart pattern (or 'wheel shape') describes how the ten planetary points are distributed around the 360° of the zodiac, independent of which signs or houses they occupy. Two charts with identical signs can feel completely different depending on whether the planets crowd one side of the wheel or ring it evenly. The classic set — named by the astrologer Dane Rudhyar and popularised by Jeff Mayo — includes the Bucket, Bundle, Locomotive, Seesaw, Splay and Splash.
Alongside the shape, the oldest and least ambiguous measurements are the hemispheres and quadrants: how many planets sit above the horizon (the public, objective half) versus below it (the private, subjective half), and how they cluster into the four quadrants of the wheel.
How we compute it
We sort the ten natal longitudes and measure every circular gap between neighbours. The largest empty arc drives the shape: 180° or more of empty wheel means everything is packed into one hemisphere (a Bundle); 150° or more gives a Bucket — or a Locomotive when the Ascendant itself leads the empty arc; a single gap of 120° gives a Splay, two large opposing gaps a Seesaw, and no large gap a Splash.
The hemisphere tally counts planets in houses 7–12 (above the horizon) against houses 1–6 (below). The quadrant tally groups the twelve houses into four sets of three. Elements and modalities are simple counts of the signs the planets occupy. Every number comes from the same ephemeris as our natal chart, so it is exact and reproducible.
What you get
After entering one birth date, time and place, the report shows:
- Your overall wheel shape, with the exact size of the largest empty arc and the two planets it runs between.
- Above- and below-horizon counts — the outer-life versus private-life balance.
- The four-quadrant tally (self, foundation, others, meaning) with any empty quadrant flagged.
- Your element (Fire/Earth/Air/Water) and modality (Cardinal/Fixed/Mutable) distribution.
How the shapes are traditionally read
The tradition treats the shape as the chart's 'weather' — the general climate the specific placements live inside. A clustered wheel (Bundle, Bucket, Locomotive) is read as concentrated, single-channelled energy with deliberate privacy about the empty half; a Seesaw as life lived between two coherent worlds; a Splay as forceful, partial coverage; and a Splash as versatile, evenly-spread interest that must learn focus.
Empty quadrants and hemispheres are described the same way: not as deficits but as territories approached consciously rather than supplied with automatic, instinctive energy. As always on this site, that is symbolic tradition, not a claim any test has validated.
A worked example: born 1 January 2000, 17:30 UTC, London
In this chart the ten planets leave one enormous empty arc of 185.7° — running forward from Saturn in Taurus all the way round to the Moon in Scorpio — so every body is crowded into the remaining 174°. Because that vacant arc exceeds 180°, our classifier reads it as a Bundle: the classic packed-wheel signature of concentrated force and a large private, unoccupied hemisphere.
The supporting tallies confirm the picture: 5 planets above the horizon against 5 below; quadrants of [0, 5, 3, 2] — with the entire first quadrant (houses 1–3, the 'self' quarter) empty; and an element balance of Fire 3, Earth 3, Air 3 but only Water 1. Change only the birth time to the 21 June solstice noon chart and the shape flips to a Splay, showing how sensitive the 'one big gap' reading is to where the clustering falls.
What this tool does not claim
Wheel-shape boundaries genuinely differ between authors — some place the Bundle/Bucket threshold at 180°, some at 150°, and schools such as the Humanistic and AstroPsychology systems add further forms. We publish one simple, deterministic rule and state it plainly so you can see exactly why a chart got its label; treat the named form as one consistent lens rather than a fixed law.
The shape is descriptive geometry: it says nothing about the quality of a life, and no controlled study supports chart-pattern interpretation or natal astrology generally. The astronomy is exact; the meaning layer is offered for reflection. All computation runs locally; your birth data never leaves your browser.
Where it sits next to other readings
Element and modality balances also appear inside the Natal Chart report, and the essential-dignity framework is the subject of our Traditional Chart tool. This page is deliberately about the big shape first — the coarse geometry that gives those finer readings their context.
Our method in one line
All ten natal positions from sub-arcsecond astronomy (VSOP87/ELP via astronomy-engine), sorted and measured for circular gaps, hemisphere/quadrant membership and element/modality counts; the shape label follows a stated, deterministic rule. Reviewed by Dr. Amara Osei, Astronomy Reviewer.
Step by step
- 1
Enter one birth record
Date, time and place. The hemispheres and quadrants need the houses, so a birth time sharpens the whole picture.
- 2
Read the shape first
The wheel form and the largest empty arc are printed at the top — start here for the chart's overall climate before any single planet.
- 3
Check the tallies
Compare above/below horizon and the four quadrants; note any quadrant with no planets.
- 4
Weigh elements and modalities
The element and modality counts sit below — the temperament backdrop the shape is painted on. Tip: a Bundle with an empty first quadrant is a very different 'self-starting' story than a Splash with one.
Frequently asked questions
- What are the six main chart patterns?
- The commonly-cited family is the Bundle, Bucket, Locomotive, Seesaw, Splay and Splash. They are distinguished by the size and number of the empty arcs around the wheel — a single huge gap, two gaps, or no gap at all — with the Locomotive adding whether the Ascendant leads the empty space.
- What does it mean if my chart has no planets in a quadrant?
- Traditionally an empty quadrant (or hemisphere) is read not as a lack but as an area you approach deliberately rather than by instinct — life 'hands you the lessons' there from outside instead of from innate habit. It is a descriptive observation about where planetary energy clusters.
- Are the shape boundaries standard?
- Not entirely. Different authors set the Bucket/Bundle/Splay cut-offs at different arc sizes and count planets differently (some exclude the outer planets). We use one simple deterministic rule and publish the thresholds so the result is transparent and reproducible.
- Do the houses matter for this reading?
- The hemisphere split (above/below horizon) and the quadrant tally depend on house positions, so they need a birth time. The wheel shape and element/modality tallies use only the planetary signs and stay exact even with an unknown time.
- Is my birth data private?
- Calculations run entirely in your browser. Your birth data is never uploaded, never stored on a server, and never shared. The geometry runs locally on your natal positions; nothing is uploaded or stored.
Written by
Elena Marchetti
Founder & Staff Astrologer
Methodology reviewed by
Dr. Amara Osei
Astronomy Reviewer
Published 2026-10-01 · Updated 2026-10-01 · Calculated with sub-arcsecond astronomy (VSOP87/ELP via astronomy-engine)