Here are Google Calendar instructions

https://www.hebcal.com/home/60/google-calendar-jewish-holidays

Shana Tova!

Hi, thanks for using Hebcal!

Rosh Hashana occurs on the first of Tishrei (September 18 at sundown) but we don't call this Rosh chodesh Tishrei.

thanks for using Hebcal!

Go to https://www.hebcal.com/shabbat and enter your location. Then look for the link that says "Print 5781" on the right sidebar (desktop) or near the bottom of the page (on mobile)

Thanks for using Hebcal, and we're so sorry to hear about this inconvenience!

Problems like this are usually caused by an incorrect timezone setting. Sometimes this is caused by downloading/subscribing to Hebcal in one timezone, then moving to a new location. If that is the case, simply removing/unsubscribing from Hebcal and then re-download/re-subscribe should fix the problem.

Hebcal event feeds are set to the correct timezone for a given location (for example, candle lighting times for Boston appear in the "America/New_York" calendar). If you didn't specify any location for candle-lighting times, Hebcal events are always set for "All day untimed" events.

We would recommend that you contact ACT! Calendar support for any further help with setting your ACT! Calendar calendar to the correct timezone for your location.

If you'd like to customize Havdalah calculations in Google Calendar, our recommendation is to remove/unsubscribe the entire calendar, and then to download/subscribe from Hebcal again with the new settings.

Here are instructions to remove Hebcal events from Google calendar:

https://www.hebcal.com/home/180/gcal-delete-jewish-calendar

Thanks for using Hebcal! Sorry to hear that  you downloaded Hebcal events with the incorrect settings and want to switch from Hebrew event titles to English transliterations.

Our recommendation is to remove/unsubscribe the entire calendar, and then to download again.

Here are instructions to remove Hebcal events from Apple, Google, Outlook and other calendar apps.

https://www.hebcal.com/home/category/import/remove

Thanks so much for using Hebcal, and for the feedback.

We do offer a way to specify the candle-lighting times before sundown. The default is 18 but you can freely change this to 40 minutes for your location.

Thanks for the bug report, and we're so sorry for the inconvenience! The link should work now. We have been upgrading the software on the Hebcal website and we somehow missed this feature.

There are multiple traditions for Havdalah times. Hebcal gives you the option to specify whether you want tzeit hakochavim (sun 8.5 degrees below horizon, a default that works well in most locations on the planet) or a fixed number of minutes after sundown.

Some use 42 minutes after sunset for 3 small stars, 50 minutes for 3 medium stars, or 72 minutes for Rabbeinu Tam. You can choose any time you want. 

Hi Tzipora and Yaakov,

Thanks again for your patience and feedback.

Another update: after some additional research, we've come to the conclusion that the sunset algorithm we were using in the new version of Hebcal wasn't accurate enough. As of yesterday, we have swapped out the sunset engine for a version that matches what we previously published on Hebcal.com and most other sources (including OU).

Some of the Hebcal event feeds are cached up to 1 week, so subscriptions on Google Calendar, iPhone, etc might not refresh until next Sunday August 23.