Run applet

The angles z of the hour lines are computed by the formula:

tan(z) = sin(φ) · tan(τ+∆φ)
φ = latitude, τ = hour angle, τ=n·15°,
∆φ is the deviation from the time zone meridian

  • Choose your location from the menu, or:

    enter (in decimal degrees) your latitude (southern negative),
    enter (in decimal degrees) your longitud
    e (western negative),

        then hit the button "Apply input"

  • Adjust the timezone offset
  • Check the box "Insert Gnomon"
  • Select "Show Hours" from the Details menu
  • Copy the left pie circle by a screen capture tool and print
  • Cut away the indicated sector
  • Fold up the gnomon and glue the two halves together
  • Set it up on a horizontal plane, the gnomon pointing to North (or South)

Example: 51,5° North und 8° East
0n 2002, September 29 at 15:50 CEST
equation of time is about + 10 minutes,
the sundial is fast at this amount.

This sundial is made of brass:

pie sundial brass

Updated: 2013, Feb 13