Birth Chart Positions Calculator

Work out birth chart positions instantly with clear inputs, formula shown and shareable results.

About Birth Chart Positions Calculator

Solar longitude is estimated from the day of the year, since the sun advances roughly one degree per day, and the zodiac divides that circle into twelve thirty degree signs. For entertainment. The solar longitude arithmetic is real astronomy to within a degree or so, but the rising sign estimate is a rough two-hours-per-sign approximation and ignores latitude entirely.

Formulas

Solar longitude

longitude = (day of year - 1) / 365.25 x 360 + 280 degrees, wrapped to 0-360

Sign

sign index = floor(longitude / 30)

Worked example

With the default values below, Birth Chart Positions Calculator returns Approximate sun sign of Aries. Change any input above and every figure here is recalculated in your browser.

Inputs used

Date of birth: 1990-07-15
Hour of birth (24h)accepts 0–23: 14

Results

Approximate sun sign: Aries
Degrees into that sign: 22.20 deg
Rough rising sign: Scorpio
Approximate solar longitude: 112.20 deg

Step by step

1Values used
2Solar longitude
3Sign
4Approximate sun sign= Aries
5Degrees into that sign= 22.20 deg
6Rough rising sign= Scorpio
7Approximate solar longitude= 112.20 deg

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Birth Chart Positions figure worked out?

longitude = (day of year - 1) / 365.25 x 360 + 280 degrees, wrapped to 0-360. Solar longitude is estimated from the day of the year, since the sun advances roughly one degree per day, and the zodiac divides that circle into twelve thirty degree signs.

Why does this matter?

For entertainment. The solar longitude arithmetic is real astronomy to within a degree or so, but the rising sign estimate is a rough two-hours-per-sign approximation and ignores latitude entirely.

What do I need to enter?

Enter date of birth, hour of birth (24h). The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.