Human Design's calculations are mathematically deterministic and reproducible — your BodyGraph chart will be identical from any computational source given the same birth data. Whether the system's interpretive framework accurately describes you is a separate question and ultimately experiential.
Short answer
Human Design's calculations are mathematically deterministic and reproducible — your BodyGraph chart will be identical from any computational source given the same birth data. Whether the system's interpretive framework accurately describes you is a separate question and ultimately experiential.
In depth
On the calculation side, Human Design uses well-defined astronomical formulas: Personality positions are computed from the Sun and Earth at your birth, Design positions are computed approximately 88 days before birth (when the Sun was 88° earlier in the zodiac). Any chart calculator using these inputs produces the same result.
On the interpretive side, the framework was synthesized in 1987 by Ra Uru Hu, who claimed it came through a "Voice" mystical experience. The system has not been validated by peer-reviewed psychological or astrological research; it is an experiential framework, not an empirical one.
The most common feedback from people who study Human Design over years is that the Type, Strategy, and Authority feel surprisingly accurate when consistently lived — particularly the description of how decisions go well versus how they go badly. This is what Ra Uru Hu called 'experimenting with your design': try it for 7+ years before judging accuracy.