Comparison

DifCal vs Monad Calendar Clock

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

DifCal

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Calculate diffraction angles for a particular crystal with a defined orientation matrix. New crystals can be added to the database. Energy/wavelength can be changed. Currently knows about 4-circle, Z-Axis and Theta-Theta diffractometers as well as 2-circle, powder and amorphous diffraction modes. Current crystals include silicon, diamond, GaAs, Muscovite (mica), graphite, many 3-5 and 2-6 crystals. There are separate screens for setting the crystal (or creating a new one), defining the orientation matrix, defining the diffractometer mode, and calculating either angles, given h,k,l, or hkl given a set of angles. With the larger screen of the iPad all the controls are visible on a single page.

About

Monad Calendar Clock

This app visualizes time through planetary and celestial movements, contrasting natural rhythms with mechanical time. It offers unique perspectives on Earth's position in space and time, showing star and planet locations, seasonal changes, and lunar phases.

Highlights
  • Planetary time and date display
  • Celestial ring visualization
  • Heliocentric and Geocentric modes
  • Star and planet location tracking
  • Seasonal and lunar phase progression
  • Twilight and sunrise/sunset times
  • Event scheduling
Features
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MONAD does something that no other clock or calendar does; it tells the planetary time and date – the solar day, lunar month & seasonal year. MONAD reveals your unique place (and perspective) in planet-centered space and time. MONAD demonstrates the biorhythms of the Earth’s biosphere, and it integrates two types of time: 1) Natural time, which is cyclic, variable, and alive, with 2) Mechanical time, which is linear, highly regular, abstract and artificial. MONAD represents a paradigm shift of planetary proportions; A New Paradigm of Time With MONAD, you see the natural rhythms of time­ proceeding in endless circles and spirals. MONAD shows the location of the stars and planets; what’s visible at night from your location on Earth. MONAD shows the progression of the four seasons and the phases of the Moon; the obliquity of the ecliptic and the Earth’s circle of illumination, and a Twilight Dial tells you the time of Sun rise and Sun set at any latitude and time of year. MONAD shows the agricultural biorhythms of the Earth’s photosynthetic biosphere. MONAD restores the Earth, and the Earth’s biorhythms and biosphere, back to the center of our collective attention and awareness. With MONAD you see the Earth globe from an unusual perspective; the north (or south) polar axial perspective. MONAD automatically places a time zone-spanning Hour Hand at your location on the globe, marking your longitude & latitude, and you see all 24 time zones, all around the globe at the same time, the whole world interconnected. MONAD has four main Modes of operation. Geocentric (Geo) Mode features planet Earth at the center of a time and date-telling, 3-dimensional celestial ring. The algorithms and programming which drive all of the astronomical activity is based on a Sun-centered and highly accurate model of the solar system which you can access in Heliocentric (Helio) Mode. Accelerate through time, into the past or future, and watch how the configuration of the solar system changes. Shift back and forth from Geo to Helio Modes, and it’s easy to see how the two perspectives are related. It’s easy to see how and why the planets have apparent retrograde activity from an Earth-centered perspective. There is so much to explore and learn in MONAD. Astro Mode features a 2-dimensional Calendar-Clock face, which makes it possible to set the time by dragging the hour hand around the dial, or you can set the date by dragging the calendar band, or zodiac band, past the Sun’s meridian or date indicator fixed at noon at the top of the dial. A Table at the top of the screen lists the precise location of the Sun, Moon and planets at any time and date, so basically this Astro screen is equivalent to an astronomy or astrology chart, at any moment in time. Astro Mode will eventually feature a Scientific Astrology Program and an Educational Astronomy Program. Event Mode is where you record and schedule personal events, in the context of important and memorable planetary events we all share. Color-coded Event Wedges are shown in the context of the 4 corners of a solar day (Sun rise, noon, Sun set & midnight), the 4 corners of a lunar month (full and dark Moon, waxing and waning half Moons), and the 4 corners of a seasonal year (equinoxes & solstices). Another unique feature of MONAD is that you can record events “in the Now,” which encourages more presence in your life. A Health Event Mode allows you to see your personal, endocrine biorhythms in the context of planetary biorhythms we all share. The 24 hour circadian Calendar-Clock face is ideally suited to organize and display health events. If you choose to have MONAD integrate with the Apple Health app (HealthKit); then health data (e.g. Sleep period and Steps) read from HealthKit is used for display within the MONAD app. MONAD is beautiful, educational & transformative, and it will change the way you see the world around you, and your place within it. MONAD – A New Paradigm of Time.

Screenshots

DifCal4 screens
Monad Calendar Clock4 screens

Verdict

The call

The clearest difference is update cadence: Monad Calendar Clock at every 6 weeks against DifCal's every 15 months. Monad Calendar Clock also leads on price ($0.99 vs $1.99). On ads, in-app purchases, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

DifCal costs $1.99 and Monad Calendar Clock $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

DifCal ships an update every 15 months, Monad Calendar Clock every 6 weeks. The most recent releases landed on May 16, 2026 and September 6, 2026 respectively.

Scorecard2 real differences · 8 level
DifCal versus Monad Calendar Clock: the parameters behind the verdict, then further details
ParameterDifCalMonad Calendar Clock
Price$1.99$0.99 — better
Rating—3.7 (14 ratings) — better
Positive reviews—22.2% of reviews
Number of ratings—14 — better
Update frequencyEvery 15 monthsEvery 6 weeks — better
AdsNoNo
In-app purchasesNoNo
Monetization—Paid
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.0 — better13.0
Further details — not scored
Size9 MB266 MB
Age rating4+4+
DeveloperSean BrennanEarth at the Center LLC

In-app purchases

None

DifCal

No in-app purchases

None

Monad Calendar Clock

No in-app purchases

Questions

Is DifCal free?
DifCal costs $1.99, with no in-app purchases.
Is Monad Calendar Clock free?
Monad Calendar Clock costs $0.99, with no in-app purchases.
Do DifCal or Monad Calendar Clock have ads?
Neither DifCal nor Monad Calendar Clock shows ads.
Which is updated more often, DifCal or Monad Calendar Clock?
DifCal ships an update every 15 months, and Monad Calendar Clock every 6 weeks. Most recently, DifCal was updated on May 16, 2026 and Monad Calendar Clock on September 6, 2026.

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