Hi, thank you for your thoughtful question!

This is a fascinating topic in Jewish history, but it's beyond the scope of what Hebcal.com covers — we focus on providing Jewish calendar dates, holiday times, and Torah readings rather than historical analysis.

Here are some great places to dig deeper:

• Wikipedia's "Tisha B'Av" article has a good overview: https://en.wikipedia.org/wiki/Tisha_B%27Av

• TheTorah.com has an excellent scholarly article called "Tisha B'Av: On What Day Were the Jerusalem Temples Destroyed?" that directly addresses your question: https://www.thetorah.com/article/tisha-b-av-on-what-day-were-the-jerusalem-temples-destroyed

• The Talmud itself (Ta'anit 29a) discusses this — you can find it on Sefaria.org

Hope that helps point you in the right direction!

Hebcal doesn’t have a denominational bias. The authors are Jewish and we embrace every movement and denomination of Judaism: Orthodox, Conservative, Reform, Chabad, Reconstructionist, Renewal, Liberal, and Humanist. We are observant of the mitzvot, and we offer this website because we want to help other Jews with their observance. This website also serves as a reference and resource for non-Jews who wish to avoid scheduling secular events in a way that would interfere with observance of Jewish holidays.

You could call us “Conservadox” if you must use a label, but we don’t really participate in any one movement of Judaism more than others. 

Hi Hilary,

Thanks for reaching out, and glad you're enjoying the Hebcal calendar (emojis and all!).

Great news — this is easy to fix! If you subscribe to the calendar using Outlook's "Internet Calendar Subscription" feature, the holidays will appear on a separate calendar layer rather than being added directly to your primary calendar. That means they won't affect your availability or set you as Out of Office.

You can find step-by-step instructions here:

https://www.hebcal.com/home/8/outlook-ics-jewish-holidays

Once you set it up this way, you'll still see all the holidays on your calendar — they just won't interfere with your free/busy status.

If you downloaded a copy of the Hebcal events and merged them into your own calendar, then yes, the major holidays are set as Out of Office (although minor holidays are not). To remove those merged events, follow these instructions:

https://www.hebcal.com/home/58/outlook-csv-delete-hebcal-jewish-calendar

Let me know if you have any further questions!

Thank you for the bug report! We found the cause of the error (an incorrectly CSS which was setting the background color to white and the text to white) and we have fixed it. If you refresh the page it should appear correctly again.

Hi Adam,

Thank you for reaching out! Great news -- you have two options to get just 5787 into Outlook.

Option 1 (Recommended): Internet Calendar Subscription 

The easiest approach is to use Outlook's "Internet Calendar Subscription" feature, which sets up a perpetual calendar feed that stays up to date automatically. It appears as a separate calendar overlay alongside your main calendar and can be managed independently. You can find setup instructions here: https://www.hebcal.com/home/8/outlook-ics-jewish-holidays

Option 2: Download 5787 only

If you'd prefer to manually import just the 5787 events and merge them into your existing calendar:

1. Go to the custom calendar creator at https://www.hebcal.com/hebcal
2. Enter the Hebrew year 5787
3. Click Download, then Outlook
4. Look for the grey "Download 5787 only" button -- this will give you just that single year to import, without re-importing 5786.

Hope that helps! Let us know if you have any other questions.

Unfortunately, Outlook 2019 does not respect or import the CATEGORIES property from iCalendar/ICS feeds.

When Outlook 2019 imports or subscribes to an ICS feed, it essentially ignores the RFC 2445 CATEGORIES field entirely. It does not map those values to Outlook's own Categories system. This is a long-standing limitation — Outlook's category system is proprietary and not wired up to the standard iCalendar CATEGORIES property on import.

So even though Hebcal is doing the right thing by tagging each event with a proper RFC 2445 CATEGORIES value like HOLIDAY or PARSHA, Outlook just drops that metadata on the floor.

Recommended workarounds to get separate colors:

1. Use Outlook on the Web or Microsoft 365 — newer versions have better category support for synced calendars. Outlook's category system requires that category names in the ICS file match pre-existing entries in your Master Category List (MCL). So even if OWA reads the CATEGORIES field from Hebcal's ICS (e.g., HOLIDAY or PARSHA), those values won't map to colored categories unless you have identically named entries already set up in your Outlook category list. If there's no match, the categories are silently dropped.

2. Use separate calendar feeds, each with their own color. For example If you’d like to include the Hebrew date for every day of the year, you can subscribe to that calendar via a separate calendar feed at our Jewish Holiday downloads page. Look for Hebrew calendar dates (English) or Hebrew calendar dates (Hebrew).

We accept some advertisements through Google AdSense. We have configured Google AdSense to block certain categories of advertisements that we feel do not belong on Hebcal.com (“Video Games”, “Alcohol”, “Gambling & Betting”,“Dating”, “Cosmetic Procedures & Body Modification”, among others). We also block advertisements from Christian and Messianic Judaism organizations.

To show your ads specifically on Hebcal.com, you should use a feature in Google Ads called Placement Targeting. Since Hebcal participates in AdSense, it is part of the Google Display Network (GDN), meaning you can "hand-pick" it as a destination for your ads.

Here is the step-by-step process to set this up:

1. Create a Display Campaign

Placement targeting is primarily available for Display Network campaigns.

• Log in to your Google Ads account.
• Click the + button and select New Campaign.
• Choose a goal (like "Website traffic" or "Brand awareness") or select "Create a campaign without a goal's guidance."
• Select Display as your campaign type.

2. Navigate to Content Targeting

Once you are setting up your Ad Group (or editing an existing one):

• Scroll down to the Content section.
• Look for the dropdown or menu labeled Placements.
• Click Add placements.

3. Target hebcal.com

• Select the Enter tab (rather than "Search").
• Type or paste hebcal.com into the box.
• Click Add 1 placement.
• Note: You can also target specific sub-pages if you only want your ads to appear on the "Shabbat Times" or "Yahrzeit" pages by entering the specific URL (e.g., hebcal.com/shabbat).

4. Adjust Targeting Settings ("Targeting" vs. "Observation")

This is a critical step to ensure your ads only show on Hebcal:

• Ensure your setting is set to Targeting.
• If you select "Observation," Google will show ads on Hebcal but also to your specified audience across the entire web. By selecting Targeting, you are restricting the campaign so it only serves ads when a user is on the specific sites you listed.

Important Considerations

• Inventory Competition: Even if you target a site, your ad isn't guaranteed to show every time. You are still competing in an auction against other advertisers. If Hebcal is popular, you may need to increase your CPM (Cost Per Mille) or CPC (Cost Per Click) bid to win the slot.
• Ad Sizes: Hebcal typically uses standard banner sizes. To maximize your chances of appearing, upload your creative in multiple formats, such as:
  • Medium Rectangle: 300 x 250
  • Leaderboard: 728 x 90
  • Wide Skyscraper: 160 x 600
• Traffic Volume: If the specific page you target has low traffic, your ads may not serve many impressions. It is often helpful to target the entire domain (hebcal.com) rather than just one specific URL.

Thanks for using Hebcal! To download holidays and candle-lighting times, navigate to https://www.hebcal.com/hebcal and fill out the form with your preferences (including specifying your location in the Candle-lighting & Fast times section of the form).

Calendars created by Hebcal are easily downloaded and imported into various calendar apps, including iPhone, Google Calendar, Outlook PC, Outlook Web, macOS Calendar, and any app that supports iCalendar (.ics) feeds or subscriptions.

Converting between Hebrew and Gregorian dates for very early years is mathematically possible (and is supported by our Hebrew Date Converter), but the results should be treated as approximations rather than historically precise dates.

The Hebrew calendar evolved into a fixed, calculation-based system beginning in the 4th century CE, traditionally associated with reforms attributed to Hillel II (a fifth generation amora). This shift replaced earlier dependence on eyewitness moon sightings and centralized rulings on leap years with a predictable mathematical framework. The detailed rules were recorded in writing over the following centuries and were later systematized by Maimonides in the 12th century, by which point the calendar had become uniform across Jewish communities by the medieval era.^[1]

Before the calendar rules were fully standardized in the early medieval period, both the Hebrew and civil calendars were influenced by local practice, observational methods, and later retroactive calculations. As a result, modern algorithms can project dates backward consistently, but they may not reflect how dates were actually observed or recorded at the time.

Any results for year 1752 CE and earlier published on Hebcal.com will be inaccurate. Hebcal does not take into account a correction of ten days that was introduced by Pope Gregory XIII known as the Gregorian Reformation.