How your chart is calculated
From a birth moment to gates and lines, including the 88-degree design side.
On this page
Four steps take you from a birth certificate to a bodygraph.
1. The birth moment becomes an instant in time
Your local clock time plus the historical time-zone rules for the coordinates of your birth city produce a single moment in universal time. This is the step where daylight saving history matters.
2. The planets are placed
An ephemeris calculates the ecliptic longitude of the Sun, Earth, Moon, North and South Nodes, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto at that instant. The app uses an open astronomical engine for this, accurate well beyond the precision Human Design needs — the gates are about 5.6 degrees wide, and the positions are good to a fraction of an arcminute.
The Earth is always exactly opposite the Sun. The South Node is always exactly opposite the North.
3. Longitudes become gates and lines
The 360-degree circle is divided into the 64 gates in the Human Design wheel order. Each gate is 5.625 degrees wide and splits into six lines of 0.9375 degrees each. A longitude therefore lands in exactly one gate and one line — and it is the narrowness of a line that makes an accurate birth time matter.
4. The design side
Human Design uses two charts, not one.
- Personality — the black side — is the moment of birth.
- Design — the red side — is the moment when the Sun was 88 degrees of arc earlier. That is roughly 88 days before birth, but roughly is not good enough: the Earth's orbit is not circular, so the Sun moves at different speeds through the year. The app solves for the exact instant at which the Sun was 88 degrees back, rather than subtracting 88 days.
Both sets of activations go onto the same bodygraph. Where a gate at one end of a channel is activated and its partner gate at the other end is too, the channel forms; the centres at both ends become defined; and definition is what produces type, authority and strategy.
What is not in the calculation
No houses, no aspects, no ascendant. Human Design uses planetary longitude and nothing else, which is why your birth place matters far less than your birth time.