The Astrolium Lilith calculator returns Black Moon Lilith by sign and house, with both Mean Lilith and True Lilith on the same output. Math runs on the Swiss Ephemeris in your browser. No login, no email, no upload.
Black Moon Lilith runs in two flavours that share the Lilith name: Mean (h13) and True (h21). For the nodal axis, see the north node calculator and the south node calculator. For the fated-encounter point sometimes layered with Lilith in synastry, see the vertex calculator.
What the calculator returns
Each result lists longitude to the arc-second, the sign and degree, the natal house under your chosen house system, daily motion in degrees, and direction (direct, retrograde, or stationary for True Lilith). Mean Lilith always reads direct at a steady rate. True Lilith can stall, reverse, and accelerate.
The two values can sit in different signs. The calculator shows the gap in degrees between Mean and True positions so you can decide which to read, or read both.
Mean Lilith versus True Lilith
Two distinct calculations. The output names which is which.
Mean Lilith (Swiss Ephemeris body code h13) uses the analytical lunar theory ELP-2000 to compute the second focus of the smoothed orbit. The result is monotonic direct motion at about 40 arc-minutes per day. Mean Lilith is the default in astro.com, Solar Fire, and most modern Western tools.
True Lilith (Swiss Ephemeris body code h21), also called osculating Lilith, solves the instantaneous orbital elements at the moment of the chart. The Moon's orbit is perturbed by the Sun and the major planets, so the true focus oscillates. It can sit 30 degrees from the Mean position and can briefly retrograde.
How the calculation works
Math runs on the Swiss Ephemeris DE431 kernel, the same library Solar Fire and Astro Gold call. Mean Lilith comes from ELP-2000. True Lilith comes from numerical integration of the instantaneous lunar orbital elements. Both positions match astro.com to the arc-second.
The calculator supports four house systems: Placidus, Whole Sign, Koch, Equal. Switch from the dropdown without re-entering birth data. Whole Sign is the default for traditional readings. Placidus is the default for modern Western.
Nothing is stored. Nothing is emailed. The chart wheel renders client-side from the returned data.
After the calculator
The Lilith position reads inside the full chart context. The ruler of Lilith's sign matters. So does any natal aspect from an outer planet. So does whatever transit is currently active.
For the full chart wheel where Lilith sits alongside every other body, see the natal chart feature and the how to read a natal chart guide. For the nodal axis often layered against Lilith, see the south node calculator. For the fated-encounter point, see the vertex calculator. To run Lilith inside a relationship reading, use the synastry calculator on both charts.