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‎docs/posts/2025/2025-11-20-CalendarTimeIntel/CalendarTimeIntel.md‎

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---
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title: Calendar-Based Time Intelligence Is Out Of This World
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description: Darian Calendar using Calendar-Based Time Intelligence
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image: /assets/images/blog/2025/2025-11-20-CalendarTimeIntel/hero.jpg
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date:
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created: 2025-11-20
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authors:
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- jDuddy
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comments: true
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categories:
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- Data Modelling
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slug: posts/CalendarTimeIntel
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links:
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- MS Docs: https://learn.microsoft.com/en-us/power-bi/transform-model/desktop-time-intelligence#calendar-based-time-intelligence-preview
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- SQLBI: https://www.sqlbi.com/articles/introducing-calendar-based-time-intelligence-in-dax
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---
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Microsoft recently released [Calendar-based time intelligence](https://learn.microsoft.com/en-us/power-bi/transform-model/desktop-time-intelligence#calendar-based-time-intelligence-preview) and it is out of this world. So much so lets try and make a Martian Calendar.
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## Calendar-Based Time Intelligence
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Calendar-Based Time Intelligence allows you to add metadata to your Date Dimension, specifying fields as periods (Year, Month, Quarter, **Week**), and you can define one of more different calendars for the same dimension. But why is this helpful?
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- **Any Calendar**: Not limited to single Gregorian, you can have Shifted Gregorian, 445, or something more exotic
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- **Sparse dates**: Classic time intelligence requires complete date columns with no missing dates between first and last dates. Calendar-based time intelligence operates on dates as-is, so if your stores are closed on weekends, you can skip those days entirely
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- **Week-based calculations**: Direct support for week granularity functions like `TOTALWTD()`
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- **Optimized queries**: If you filter by a defined period (Year, Month etc.) the engine can filter by the period (`Year: {2021, 2022, 2023}`), rather than falling back to date (`Date: {01-01-2021,....,31-12-2023}`), resulting in smaller cache and faster queries
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## Martian Calendar
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On Mars a day (Sol) is 24 hours, 39 minutes, and 35 seconds, nearly 40 minutes longer than a day on Earth, and the Martian year is 668.5907 sols (686.9711 Earth days). One proposed calendar for Mars is the [Darian calendar](https://en.wikipedia.org/wiki/Darian_calendar), which splits the year into 24 months with varying lengths.
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=== "Darian Calendar"
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|MartianYear | MartianMonth | SolOfMonth | MonthName | Date | SolsSinceEpoch |
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|---|---|---|---|---|---|
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|200 | 1 | 1 | Sagittarius | 1-Sagittarius-200 | 1 |
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|200 | 1 | 2 | Sagittarius | 2-Sagittarius-200 | 2 |
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|200 | 1 | 3 | Sagittarius | 3-Sagittarius-200 | 3 |
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|200 | 1 | 4 | Sagittarius | 4-Sagittarius-200 | 4 |
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|200 | 1 | 5 | Sagittarius | 5-Sagittarius-200 | 5 |
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=== "DAX"
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```dax
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Dates =
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VAR StartMartianYear = 200 // Adjust as needed
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VAR EndMartianYear = 220
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VAR EarthEpoch = DATE(1609, 3, 11) // Telescopic Epoch (Start of Mars Year 0)
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VAR SolsPerEarthDay = 1.02749125
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VAR StandardYearSols = 668 // Sols in a standard Martian Year (Darian Calendar)
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VAR LeapYearSols = 669 // Sols in a leap Martian Year (Darian Calendar)
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VAR MonthNames =
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DATATABLE(
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"MartianMonth", INTEGER,
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"MonthName", STRING,
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{
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{1, "Sagittarius"}, {2, "Dhanus"}, {3, "Capricornus"}, {4, "Makara"},
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{5, "Aquarius"}, {6, "Kumbha"}, {7, "Pisces"}, {8, "Mina"},
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{9, "Aries"}, {10, "Mesha"}, {11, "Taurus"}, {12, "Rishabha"},
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{13, "Gemini"}, {14, "Mithuna"}, {15, "Cancer"}, {16, "Karka"},
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{17, "Leo"}, {18, "Simha"}, {19, "Virgo"}, {20, "Kanya"},
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{21, "Libra"}, {22, "Tula"}, {23, "Scorpius"}, {24, "Vrishika"}
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}
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)
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VAR IsLeapYear =
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SELECTCOLUMNS(
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GENERATESERIES(StartMartianYear, EndMartianYear, 1),
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"MartianYear", [Value],
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// Your Leap Rule: Odd years OR years ending in 0 (Custom Darian)
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"IsLeap", MOD([Value], 2) = 1 || MOD([Value], 10) = 0,
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"SolsInYear", IF(MOD([Value], 2) = 1 || MOD([Value], 10) = 0, LeapYearSols, StandardYearSols)
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)
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VAR CalendarMonthSols =
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SELECTCOLUMNS(
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GENERATE(
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IsLeapYear,
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GENERATESERIES(1, 24, 1) // 24 months
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),
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[MartianYear],
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"MartianMonth", [Value],
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"SolsInMonth",
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IF(
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MOD([Value] - 1, 6) + 1 <= 5,
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28,
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IF([Value] = 24 && [IsLeap], 28, 27)
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)
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)
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VAR CalendarDayBase =
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SELECTCOLUMNS(
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GENERATE(
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CalendarMonthSols,
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GENERATESERIES(1, [SolsInMonth], 1)
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),
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[MartianYear],
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[MartianMonth],
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"SolOfMonth", [Value]
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)
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VAR AddSolsSinceEpoch =
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ADDCOLUMNS(
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CalendarDayBase,
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"SolsSinceEpoch",
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VAR CurrentYear = [MartianYear]
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VAR CurrentMonth = [MartianMonth]
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VAR CurrentSol = [SolOfMonth]
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// Calculate total sols from all complete previous years
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VAR SolsFromPreviousYears =
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SUMX(
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FILTER(IsLeapYear, [MartianYear] < CurrentYear),
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[SolsInYear]
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)
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// Calculate sols from complete previous months in current year
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VAR SolsFromPreviousMonths =
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SUMX(
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FILTER(CalendarMonthSols,
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[MartianYear] = CurrentYear && [MartianMonth] < CurrentMonth
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),
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[SolsInMonth]
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)
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RETURN SolsFromPreviousYears + SolsFromPreviousMonths + CurrentSol
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)
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VAR Combine =
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ADDCOLUMNS(
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NATURALLEFTOUTERJOIN(
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AddSolsSinceEpoch,
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MonthNames
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),
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"Date", [SolOfMonth] & "-" & [MonthName] & "-" & [MartianYear]
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)
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RETURN
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Combine
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```
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Since the `[Date]` field is not a tradition date, we are not able to mark this as a date table. But we are still able to define our calendar.
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![Define Calendar](DefineCalendar.png)
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And we can create some fake weather data to test our calendar.
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??? demo "Weather Table"
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```dax
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FactWeather =
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VAR BaseTemp = -60 // Average global surface temp on Mars in Celsius
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VAR TempRange = 25 // Typical daily temperature variation
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VAR MaxDailyVariance = 5
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RETURN
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ADDCOLUMNS(
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SELECTCOLUMNS(
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Dates,
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"Date", [Date],
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"AvgTemp_C", BaseTemp + (RAND() * TempRange)
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),
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"MinTemp_C", [AvgTemp_C] - (RAND() * MaxDailyVariance),
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"MaxTemp_C", [AvgTemp_C] + (RAND() * MaxDailyVariance)
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)
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```
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Then we are able to use any of the regular time intelligence functions by specifying our calendar, like seeing what the weather was like last year.
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```dax
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Avg Temp Previous Year =
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CALCULATE(
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[Avg Temp],
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SAMEPERIODLASTYEAR( 'Darian')
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)
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```
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![Weather Last Year](./TempLastYear.png)
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## Conclusion
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Calendar-Based Time Intelligence opens up exciting possibilities beyond traditional Gregorian calendars, and final Martian's can use DAX's Time Intelligence functions.

‎docs/posts/2025/2025-11-20-CalendarTimeIntel/DefineCalendar.png‎

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‎docs/posts/2025/2025-11-20-CalendarTimeIntel/TempLastYear.png‎

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