Sundial Builder

HORIZONTAL SUNDIAL

Built on a flat horizontal surface.

• Hour lines converge toward true south in the northern hemisphere, or true north in the southern hemisphere.
• The gnomon is fixed at the "center of the sundial," where the hour lines meet, is tilted relative to the horizontal plane by an angle equal to the absolute value of the local latitude, it must point to the celestial north pole (northern hemisphere) or celestial south pole (southern hemisphere).

Required data:

• Latitude between 5° and 80° (use negative values for southern hemisphere)
• Longitude (used only to calculate correction between solar time and civil time)
• Location can be entered manually or retrieved via the device's GPS
• Gnomon length: between 10 cm and 30 cm. The final tilted length is calculated by the app
• Equation of Time and longitude correction are shown on screen and in the CSV file

VERTICAL SUNDIAL

Built on a vertical wall facing any direction (south, west, east, north, or intermediate).

• Hour lines start from the "center of the sundial" and extend downward
• The gnomon is fixed at this center point
• The gnomon is inclined based on latitude and wall orientation. It equals the latitude only when facing due south or due north
• The gnomon must point to the celestial north pole (northern hemisphere) or celestial south pole (southern hemisphere)

Required data:

• Latitude between 5° and 80° (use negative values for southern hemisphere)
• Longitude (used only for time correction)
• Location can be entered manually or via GPS
• Gnomon length: between 10 cm and 30 cm. The app computes the final inclined length
• Wall orientation:
  • Northern hemisphere: from 270° (east) to 360°≡0° (south) to 90° (west)
  • Southern hemisphere: from 270° (east) to 180° (north) to 90° (west).

GENERAL NOTES

• The scale factor changes the sundial’s visual size but not the CSV values
• Sundials near the edge of a time zone may show up to 30 minutes of difference between solar time and civil time
• The app calculates the inclined gnomon length from the center
• Alternatively, you can place a perpendicular gnomon from the origin point; in this case, only the tip’s shadow indicates the time
• Wall orientation is measured clockwise from south:
  • 0° = South
  • 90° = West
  • 180° = North
  • 270° = East