Sundial calculation

Here you will find all you need to construct your own wall sundial.

• Sundial calculation as a table with a scaled-down sundial drawing. This allows you to paint your own sundial on the wall. Please specify your address (street, town), wall deviation (south deviation) and size of the sundial when ordering. 

• Sundial calculation with design. If you wish, we can not only take care of the calculation, but also the design, which was developed and patented by Carlo Heller. The delivered design is then immediately suitable for transfer onto the wall of your house. On request, we can also provide a template with which the sundial dial can be transferred onto the wall with paint and a brush. Please enquire about the additional costs.

• Adjustable gnomon in standard length 800 mm or in a length of your choice (max. 800 mm). The ball joint allows the gnomon to be aligned precisely parallel to the earth's axis. The latitude measuring device with compass is suitable for this purpose.

• Latitude measuring device for correct angle adjustment of the gnomon (diameter 4-12mm). With this inclinometer, which can be conveniently attached to the gnomon and clamped in place, you can precisely adjust the gnomon for the latitude. The latitude measuring device is also ideal for setting up equatorial sundials (garden sundials, armillary spheres, millennium sundials) that do not have a latitude scale.

• Measuring table to measure the wall deviation (declination) by the Sun.  Including software for your computer or laptop (Windows 11 or older). The latter can be purchased separately. The wall deviation or declination is the angle, that a wall's perpendicular makes with due south (i.e. a wall facing S has d=0°). Walls declining westward have positive declinations, those eastward, negative.

• The PC software for determining wall deviation (south deviation) can also be purchased separately and runs on Windows XP to Windows 11. It also includes a very useful LAT clock, which calculates the local apparent time (solar time) from the PC time (standard time), the longitude and the equation of time. You can easily set your sundial using the real-time LAT clock. The software is delivered as a download to your email address.

• Determination of wall deviation (south deviation) from Google Maps or from the land registry plan of the building. The meridian convergence (difference between map N and geographical N) is taken into account.

• CET-LAT table for determining Central European Time (CET) from the local apparent time (LAT) read from the sundial for your location. The time difference is calculated for each day of the year from the longitude-dependent local time difference and the daily equation of time and is given in h:mm:ss. The values are determined for a leap year cycle (average of four years, deviation max. 25 seconds). On request, the table can also be calculated for a specific year; please specify when ordering. This table is very well suited for adjusting a sundial with the help of a wristwatch. Calculation also possible for other standard times.

• CET-LAT wall chart for determining Central European Time (CET) from the local apparent time (LAT) read from the sundial for your location. Unlike the table of the same name, the values are given in minutes (rounded) to simplify the calculation. If your sundial is ‘local time corrected’ (LAT of 15°E), please let us know. The CET-LAT wall chart is a practical accessory for any sundial to determine the time (CET). Also available for other standard times.

Take a look at examples of homemade wall sundials on our German product page: https://www.helios-sonnenuhren.de/de/selbstbau-sonnenuhr