If the five Types are the headline of Human Design, the nine centres are the alphabet underneath. Reworked from the Hindu chakra system — expanded from seven to nine — they are the energy hubs of the BodyGraph, and the pattern of which ones are defined or open is what determines your Type, your Authority, and where you are consistent versus where you are shaped by others. This article tours all nine, explaining what each governs and how its defined and open versions differ.
From Seven Chakras to Nine Centres
The nine centres are Human Design's reworking of the Hindu-Brahmin chakra system. Where classical yoga describes seven chakras running up the body, Ra Uru Hu adapted and split them into nine geometric centres, redistributing their functions to fit the rest of the system. The names — Head, Ajna, Throat, G or Identity, Heart or Ego, Sacral, Solar Plexus, Spleen, and Root — echo the chakras in places but carry their own specific meanings. It is an adaptation, not a copy.
Each centre is a hub for a particular kind of energy and a particular domain of life. Four of them — the Sacral, Heart, Solar Plexus, and Root — are "motors," the sources of power in the chart; the other five process, transmit, or perceive. In the BodyGraph, each centre is either coloured in (defined, consistent, reliable) or left white (open, taking its character from outside). With that map in hand, here is what each of the nine actually does.
The Head, Ajna, and Throat
The Head centre, at the top, is the pressure centre of mental inspiration — it generates questions, wonder, and the urge to make sense of things. Defined, it is a consistent source of mental pressure and inspiration; open, it can get caught trying to answer everyone else's questions. Just below sits the Ajna, the centre of conceptualisation, analysis, and certainty. Defined, it gives a fixed way of thinking and reliable mental processing; open, it is flexible but can over-grip the idea of being certain.
The Throat is the centre of communication and manifestation — the hub through which energy becomes speech and action. It is the great connector of the chart, because a motor wired to the Throat is what allows a Type to initiate. Defined, the Throat gives a consistent voice and way of expressing; open, communication can feel pressured, with a tendency to talk to get attention. Together these three are the head-to-voice pathway, turning inspiration into expression.
The G, Heart, and Sacral
The G or Identity centre, at the chart's heart, governs identity, love, and direction in life. Defined, it gives a consistent sense of self and a steady inner compass; open, identity and direction are more fluid and shaped by environment, which is part of why the right place and people matter so much for some people. Beside it sits the Heart or Ego centre, the motor of willpower, want, and self-worth. Defined, it gives reliable willpower and drive to prove things; open, it should avoid making promises to prove worth.
The Sacral is the great life-force motor and the single most consequential centre, because its definition is what separates Generators from everyone else. Defined, it is the deep, renewable engine of work and vitality and the source of the gut response; the roughly 70% of people who are Generators or Manifesting Generators all have it defined. Open, as in Manifestors, Projectors, and Reflectors, there is no consistent access to that engine, which is why those Types are not built for relentless output.
The Solar Plexus, Spleen, and Root
The Solar Plexus is the motor of emotion, feeling, and emotional waves. Defined, it gives Emotional authority — a person who experiences moods as waves and should wait for clarity over time rather than deciding in the moment. Open, a person amplifies and absorbs the emotions around them and must learn what is genuinely theirs. The Spleen is the centre of intuition, instinct, health, and survival — a quiet, in-the-moment knowing. Defined, it gives reliable gut-level intuition; open, it can drive a tendency to hold onto things, or people, out of fear.
The Root, at the base, is a pressure centre and a motor of drive, stress, and the impulse to get things done. Defined, it gives a consistent way of handling pressure and a steady drive; open, pressure can feel like a constant rush to clear the to-do list so the stress will stop. These last three centres are where much of Human Design's talk of emotion, intuition, and stress lives. To understand how defined and open versions of any centre differ, read defined vs undefined centers, and to see how the centres sit in the chart, see the BodyGraph explained.