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Sundial Design Software

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This page lists, first, all the programmes we know about which have been recommended by members, and then others which we have not had any feedback on. We welcome news of other programmes and will include them here - it is very helpful if you can do a short review of what they do.
  • A computer programme which will calculate hour lines for horizontal dials, vertical declining/reclining dials, analemmatic horizontal dials, analemmatic vertical declining dials, azimut horizontal projective dials and azimut vertical declining projective dials is now available in Italian, English and Czech versions at The programme is freeware - new features are added every month

  • A new computer programme, which is freeware and appears very easy to use, is availble at It produces a graphical output for horizontal dials and for vertical dials declining up to 45 deg.

  • A new section of Carl Sabanski's website at helps novice diallists to design and build a sundial. It offers a number of simple spreadsheets he hqas developed. There are also a couple of PDF templates. It shows how programs such as ZW2000, Shadows and The Dialist's Companion can be used to design sundials.

  • The new vertical sundial calculation programme can be found at This programme also calculates vertical sundials in the Souther hemisphere.

  • The home page of our collaborator Fer de Vries (who has translated much of "Sundials on the Internet" into Dutch) which includes a uniform method to calculate flat sundials which is usable all over the world. The software can be downloaded from the web. There is also a help file called which can be downloaded from the home page.

  • The Sundial Constructor programme by EJ Swingler and SJ Reeves which is Windows- based and calculates all the hour lines and gnomon angles for flat dials. This programme was reviewed in the October 1996 is on sale through the British Sundial Society at £20. Please send your orders/enquires to the Secretary, 112 Whitehull Road, Chingford, London E4 6DW quoting "Sundials on the Internet"

  • The Basic Disk of the North American Sundial Society which is sent free to all new members, and contains a number of useful sundial programmes

  • Ing. Gianni Ferrari, Via Valdrighi 135 - 41100 Modena - Italy Email : Gianni Ferrari has a group of programs to calculate several types of Sundials.
    • - Sundials on a whatever plane and a whatever place
    • - Sundials with ancient hours
    • - "Monofilar" Sundials
    • - Bifilar Sundials
    • - Sundials on the inner and on the outer surface of a vertical cylinder
    • - Sundials on the inner and on the outer surfaces of an horizontal cylinder ; also rings with fixed or movable hole, ecc.
    • - Sundials on the inner and on the outer surfaces of a vertical cone ( or of a trucated cone)
    • - Time's Equation curves
    The whole package is about 1.5 Mb long and compressed is about 800 kb The programs are available at 40 US$. A demo version is available.

New arrivals - welcome

If you use any of these programmes, please let us know what you thought of them - others would find it helpful. Other programmes we have heard about are
  • Chris Haji-Michael has a new sundial design program at

  • Calculate a sundial for any position on earth

  • Sundial Computations

  • - new free Shadows software from Francois Blateyron, in French and also in English, which calculates the hour lines for any flat sundial

  • Bill Huffman has told us recently that he is very interested in the "sundial generator". Very quick and neat. The location is Hope you will find it useful..

  • Greetings: I have enjoyed your web page immensely. I have just posted at spreadsheet I have used for some time to calculate solar angles in conjunction with sundial calculations. I would appreciate any comments you might have as to its accuracy or utility. [This site also has a lot of notes about bird-watchng in Arizona]
    For locations in the US (and now also worldwide), values calculated can be compared to the US Naval Observatory's calculations at

  • The Diallist programme distributed with the joining pack to members of the North American Sundial Society is extremely useful for giving up-to-the-second calculations of the Equation of Time and the azimuth and altitude of the sun, for any latitude and longitude, and for any date over a century or so. We have heard recently that it is also available as a download from

Please send us an E-mail from you if you know of any others which we don't know about!. Thank you

This part of this page originally appeared as an article by Harold Brandmaier in Vol 4, Number 4 (December 1997)of The Compendium, the journal of the North American Sundial Society

Sundial design consists of the determination of the hour-lines or equivalent time markers on the sundial surface, the position of the shadow producing object relative to that surface and the limits of operation of the sundial. Early design procedures were manual, either graphical constructions or, later, the solution of the equivalent analytical equations using tables of logarithms and trigonometric functions. During the last thirty years, the development of the scientific calculator, the later models of which are programmable, and of course the personal computer, considerably reduced the tedium of repetitive calculations. Most recently, computer aided drafting has become useful. This article is a brief summary of the capabilities of a number of computer programs currently available for sundial design.

The accompanying table lists the characteristics of each program, particularly the types of sundials each is capable of designing. The availability of these programs is:

ZONWVLAK - Internet download from or digital bonus with the December 1994 issue of The Compendium. (See also below)

SUNDIALS - Gianni Ferrari, Via Valdrighi 135, 41100 Moderna, Italy. E-Mail: also below)

CADRAN - Pierre Joseph Dallet, 4 Rue des Fougeres, 19200 Ussel, France.

LAMONT - Volume 4, Number 1 of the disk version of The Compendium.

SHADOWS - Internet download from (See also below)

SUNDIALS CONSTRUCTOR - The Sail-Loft, Whitfords Yard, Fowey, Cornwall PL23 1BH, England.(See also below)

A complete evaluation of these programs including verification of the calculated results is beyond the scope of this article. However, the table allows a program to be chosen that best satisfies the sundial designer's requirements. To use the table, a few explanations are required. A "Y" indicates that the capability listed in the leftmost column exists for the program listed in the uppermost row. Other letters refer to the underlined letter in the leftmost column. While all named planar sundials with a style parallel to Earth's axis can be categorized as inclining / declining dials, a few of the programs include specific named dials. For example, vertical direct, vertical declining, polar and flat equatorial dials; these are noted in the table. SUNDIALS' monofilar category is unique. It considers sundials with shadows cast by any straight line on a flat surface with day-lines that are specified curves (e.g. circles and ellipses). Submerged dials are those whose faces are covered by a material whose refractive index is different from air - for example, water.

Only SUNDIALS and CADRAN are capable of designing non-planar sundials. In studying these programs, the author learned that the shadow for "hat" type cylindrical and conical dials is cast by the edge of a round flat plate perpendicular to the axis and concentric with the dial surface.

The on-line documentation accompanying each program is not extensive. Items that may be missing include coordinate system definition, symbol definition, the signs (+/-) of angles in either the program input or output, whether angles are in decimal degrees or hour-minute-second format and their precision, error messages and their interpretation, and sample designs to guide the designer. Further, unless the designer understands French, it is difficult to use a number of what may be useful options in CADRAN.

Of interest to most dialists are planar sundials, either inclining or declining or, less frequently, both. The writer used the data for the vertical sundial, declining East, on his garage wall to partially verify most of these programs. This sundial was designed using a program developed by the writer for a now obsolete computer. All the results compared favorably. More stringent tests might include a "Great Decliner" that faces almost but not quite due East or West, and a general inclining and declining dial that is parallel to Earth's axis, for example the dial on pages 340-1 of Moxon's "Mechanick Exercises or the Doctrine of Handy-Works". As a guideline, each program option that is to be used should be verified either by using the results from another program, data in the sundial references, or the results of a manual calculation if feasible.

Finally, the user of any of these programs should not hesitate to contact the program source for further information on which to base a selection or, once procured, for help in using the program.

Harold Brandmaier 63 Florence Road, Harrington Park, NJ 07640

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