How can you compare astrology software using the same chart?

Before choosing an astrology program, ask a practical question: Can I repeat my own work here with the same inputs and settings? A large catalogue of techniques may omit the method you actually use. A simpler tool may make your everyday task easier to inspect. Try these seven checks with sample data, never with a client's private birth details.

1. Does it run on the device you use?

A desktop installation, browser service and phone app come with different working conditions. Check the supported operating system, whether the installer is available, how updates work, whether you need a connection and what the licence covers. Vendor pages change: Solar Fire V9 is presented as Windows software; Astro Gold describes one desktop licence covering Windows and macOS; TimePassages publishes requirements for both desktop platforms. These are vendor descriptions, not the results of our own installed comparison.

Our interest is clear: the Hermes team wrote this article. Hermes provides a Windows installation path through its Programs page and personal delivery area. A Mac customer download is not available yet. Check the current platform and language scope on the Programs page before buying.

2. Do matching birth details represent the same instant?

Start with date, time, location and time zone. Confusing local time with UTC changes the instant you calculate. Historical daylight-saving rules also change: the IANA Time Zone Database records local-time history and rule updates. Identical clock digits on two screens therefore do not prove identical inputs. Record the selected zone and the resulting UTC instant.

“Uses Swiss Ephemeris” is useful technical information, but it does not mean every chart setting is identical. Astrodienst's Swiss Ephemeris documentation describes planetary calculation, time conversion, sidereal modes and house calculations separately. Compare the ephemeris, time handling and selected methods together.

3. Which settings can change the result?

Hold the zodiac, house system, lunar-node option, ayanamsha and body list constant. Then change one setting. If you compare Placidus with Whole Sign houses in a tropical chart, inspect planetary longitude, house boundaries and house placement as separate observations. Do not label every discrepancy a software error before you identify the rule that changed. Hermes discusses these choices in its chart-settings guide and house-systems article.

4. Can the screen answer your research question?

Try three tasks: create a natal chart, change one setting on that chart, then open a timing or location technique and return to the original view. Count neither menu items nor marketing claims. Look for the selected value, the changed value and a readable result. Astrodienst's article on computer astrology describes the benefit of rapid calculation and drawing while distinguishing computer-generated interpretation from a practitioner's assessment. A calculated position and your reading of it are different kinds of information.

5. Can you reopen your work?

Save a chart, close it and reopen it. Are the date, time, place and method settings still there? Ask about export, backup and migration from another program. “I can export a PDF” is not the same as “I can restore my calculation settings and client record.” Read the privacy and backup terms before testing with real client data.

6. Is the purchase scope clear?

A one-time licence, subscription, mobile add-on and free companion tool cover different things. Check device limits, updates, delivery timing, support and refund terms on the current product page. Do not copy a competitor's price from an old article. For Hermes, evaluate the main program separately from the free AstroPen and the Asteroid Helper, whose installer has not yet been published. Current availability belongs on the Programs page.

7. Run one small, repeatable exercise

Synthetic comparison input: 1 January 2000, 12:00 UTC; 41°N, 29°E; tropical zodiac, Placidus and True Node. The completed Hermes baseline follows; the second program remains your own comparison exercise.

For the first pass, match every setting in both programs. Then change only the house system to Whole Sign and record the new results on another row. If you see a large difference, revisit the time input and methods first. If it remains, consult the publisher's calculation documentation. A shared ephemeris name is not an independent accuracy test.

You do not need one “best program for everyone.” You need a tool that lets you repeat your method and understand its boundaries. Explore Hermes's current Features and check actual delivery on the Programs page.