Summary
Connect Outlook and Google in Keeper.sh and send busy-block copies of the Outlook calendar onto the Google calendar a partner actually checks. One tick for this leftover. Copies land while the laptop is shut.
Work or personal life lives in Outlook; those hours must exist on Google to sync Outlook Calendar to Google Calendar. If the job is the other way — Google hours onto Outlook — see /blog/sync-google-calendar-with-outlook. If they only need Google visible inside Outlook, /blog/add-google-calendar-to-outlook covers Subscribe from web, which is the wrong direction for this leftover. For a named Outlook share, see /blog/how-to-share-outlook-calendar. If Apple is the source, see /blog/how-to-sync-apple-calendar-to-google-calendar.
Outlook Add calendar / Subscribe from web overlays Google into Outlook — wrong direction. Google From URL / a published ICS is pull-only and only if the source is public. File → Save Calendar then Google Import & export is a snapshot. Microsoft 365 sharing to Gmail is an ICS on Microsoft's clock. OGCS can write Outlook onto Google, but only while that Windows PC stays on.
Keeper.sh writes private copies (placeholder title from the source calendar) onto the Google calendar that stays empty. Google and Outlook notify Keeper.sh on Pro, so a copy can land the moment the original changes. Nothing of theirs has to stay awake.
The rest of this page shows why Subscribe from web, From URL, export/import, and OGCS fail that leftover job, then the numbered Keeper.sh setup.
Subscribing Google into Outlook is the wrong direction
Microsoft documents Subscribe from web as a way to see your Google Calendar in Outlook. The control path is Add calendar → Subscribe from web → paste the Google Secret address in iCal format → Import.
Microsoft says: "Below the calendar grid on the left, select Add calendar, then select Subscribe from web." And: "Paste the copied URL into the address bar, then select Import." (View your Google Calendar in Outlook, fetched 29 Aug 2026.) The Google Secret address lives at Settings → calendar name under Settings for my calendars → Integrate calendar → Secret address in iCal format. Google warns: "Important: Only you should know the Secret Address for your calendar. Do not share this address with other people." Google also says: "If your calendar application doesn't have a full sync option, or if you want a read-only view of one calendar, you can sync your calendar to the application using a link to iCal." And: "In the “Secret address in iCal format” section, copy the link." (Sync your calendar with computer programs, fetched 29 Aug 2026.)
Microsoft's import/subscribe article adds: "When you subscribe to a calendar, your calendar will automatically refresh if the other calendar is updated. This can sometimes take more than 24 hours." And: "This update can take more than 24 hours, although updates should happen approximately every 3 hours." (Import or subscribe to a calendar in Outlook.com or Outlook on the web, fetched 29 Aug 2026.)
Add calendar / Subscribe from web (and classic From Internet) is Google-into-Outlook overlay on Microsoft's clock. If that was the whole job, /blog/add-google-calendar-to-outlook and they can stop. It is the wrong direction for Outlook hours that must exist on Google.
Google From URL and a published ICS are pull-only
Work hours live only on Outlook. A partner looking at Google Find a time or a personal Google week still sees that hour as free. Overlay does not fix this: a subscribed ICS is not a first-class Google event. A Microsoft Tech Community thread from 4 Jun 2025 describes exactly this failure: subscribed .ics events "Do not show up in Scheduling Assistant availability" and "Do not mark you as 'busy' for others." The same thread notes the reverse, which is this page's direction: "The problem also exists in my personal calendar… if I go to book an appointment, my work's busy times are not visible during the appointment booking process." The solution post lists what will not work: "Subscribing via an .ics feed… Importing a static .ics file… Viewing a calendar in 'overlay' mode — it shows up visually but does not influence your free/busy availability." (Sharing personal calendars with work profile and showing busy times, 4 Jun 2025.)
Google's From URL path is documented at Subscribe to someone else's calendar (fetched 29 Aug 2026). Google says: "To subscribe to a new calendar, you must use a computer web browser. You can't subscribe to a calendar in the Google Calendar app for Android, iPhone, or iPad." And: "Important: You can only add a calendar with a link if the other person's calendar is public." The steps are: "On the left, next to 'Other calendars,' click Add other calendars From URL." "Enter the URL of the published calendar." "Click Add calendar." "The calendar displays on the left, under 'Other calendars.'"
Microsoft 365 sharing to a Gmail recipient produces an ICS URL. Microsoft says: "If the recipient is an Outlook.com user, the sync will happen approximately every three hours." "If the recipient is in Gmail.com, the calendar might be updated every 24-48 hours." And: "This configuration currently generates an Internet Calendar Subscription (ICS) URL. The shared calendar recipient adds the shared calendar using the ICS URL, and the sync timing is determined by the recipient's calendar service." (Calendar sharing in Microsoft 365, fetched 29 Aug 2026.)
Google publishes no refresh interval for a URL-added calendar.
/docs/accounts-and-calendars: "A calendar subscribed from a link is read-only, so it can send events but never receive them."
From URL / a published ICS / Microsoft 365 sharing to Gmail overlays a read-only feed on the recipient's clock, and From URL only works if the source is public. It is not a copy onto the Google calendar a partner books against. How to add Outlook Calendar to Google Calendar as a visible overlay is From URL — they can stop if seeing the grid was the whole job.
Exporting Outlook into Google is a snapshot
Microsoft's documented Outlook-to-Google path is File → Save Calendar in Outlook, then Import & export in Google.
Microsoft says: "When you export your Outlook calendar to Google Calendar, you're exporting a snapshot of the calendar. Any changes you make to your Outlook calendar won't automatically be reflected in Google Calendar." The Outlook steps: "In Outlook, open the Calendar, and select the calendar you want to export." "Click File > Save Calendar." The Google side: "Along the left side of the screen, select Import & export." "Click Select file from your computer." "Pick the file that you created when you exported your calendar from Outlook, and then click Open." (Export an Outlook calendar to Google Calendar, fetched 29 Aug 2026.)
The general ICS-import rule is the same: "When you import an .ics file, you get a snapshot of the events in the calendar at the time of import. Your calendar doesn't refresh the imported events automatically -- even if the calendar's owner makes an update." (Import or subscribe to a calendar in Outlook.com or Outlook on the web, fetched 29 Aug 2026.)
Export/import is a one-time snapshot. It never updates itself and it never becomes a live copy. If they meant import a Google .ics into Outlook, that is the other direction — /blog/add-google-calendar-to-outlook.
OGCS only runs while the PC is on
Outlook Google Calendar Sync (OGCS) is a Windows desktop app, not a first-party Microsoft feature. Its FAQ states: "Granted, it would be nice for OGCS not to need installing on a PC that is powered on for it to sync." It also says: "From its origin, OGCS has been focused on users who are sat behind a corporate firewall connecting to Exchange accounts and want to sync out to Google." On cadence: "scheduled syncs are restricted to a maximum frequency of 15 minutes, or 120 minutes if Push Sync is also enabled." And: "Push Sync triggers an automatic sync within 2 minutes of any calendar change within Outlook." (OGCS FAQ, page last edited 13 Jan 2025; fetched 29 Aug 2026.)
OGCS can write Outlook onto Google, but only while that Windows PC is powered on. It is not unattended when the laptop is shut. Keeper.sh does not replace OGCS for air-gapped Exchange; it replaces it when the PC cannot stay on.
Put Outlook hours on Google Calendar with Keeper.sh
Connect Outlook and Google in Keeper.sh. /docs/accounts-and-calendars: "Connecting copies nothing by itself. Events only move once you send them to another calendar."
- Sign in to Keeper.sh. Connect Outlook. Connecting copies nothing.
- Connect Google. Two accounts is the Free allowance.
- Open the Outlook calendar page. Under Send Events to Calendars, tick the Google calendar. One connection, Outlook → Google. /docs/sending-events-to-another-calendar: "Each calendar you tick becomes one connection. Events are copied into it, one way, and the copies are kept corrected as the originals change."
- If they also need Google hours on Outlook, open the Google calendar page and tick the Outlook calendar. Second connection. That is two of Free's three connections. /docs/sending-events-to-another-calendar: "Events flow into the calendars you ticked and never back. For a change in either calendar to reach the other, set up two connections, one from each calendar's page." The leftover the other way is covered at /blog/sync-google-calendar-with-outlook.
- Leave the privacy defaults. /docs/what-a-copied-event-shows: "A copied event shows the name of the calendar it came from in place of the real title, and no description or location." Guest lists are never copied. Description and location toggles are Pro.
- Confirm on Google: a real event, named after the source calendar, no notes, no location, no guest list. Wait for the next write.
If nothing arrives, see /guides/event-has-not-arrived. If two of something appear, see /guides/same-event-appears-twice. A subscribed calendar that looks out of date is covered at /guides/subscribed-calendar-out-of-date. Untick the calendar in Send Events to Calendars and new events stop being copied. Events already copied stay where they are. A password or admin revoke means re-authenticating the account at /docs/accounts-and-calendars. Work and personal leftover: /recipes/sync-work-and-personal-calendars. Titles on one side only: /recipes/keep-personal-details-out-of-work.
Keeper.sh reads sources every minute on every plan. Free destinations write every 30 minutes. Pro writes every minute, and Google and Outlook notify Keeper.sh so a copy can land within seconds. /docs/plans-and-limits: "On Pro, Google Calendar and Outlook notify Keeper.sh the moment an event changes, so the copy lands within seconds." And: "Pro is $5 a month, or $45 a year paid annually." Keeper.sh does not notify them. iCloud stays on the timer on both plans (/docs/plans-and-limits: “iCloud, Fastmail and other CalDAV calendars are checked on a timer on either plan, because Apple publishes no way for a calendar tool to be told an event changed.”). Guest lists are never copied. Free includes 2 accounts, 3 connections, and 1 shareable link.
A pasted share, ICS, or subscribe link is pull-only — never a destination. If they connected a URL instead of signing in to Google or Outlook, they can send from it, not into it. Signed-in iCloud (Apple ID and an app-specific password) is a source and a destination; one Apple ID, two mappings if both ways.
Why a Keeper.sh copy instead of a feed or a PC left on
Subscribe from web overlaid Google into Outlook, and From URL / an ICS share only overlaid a read-only feed on Google — Keeper.sh writes a private copy of Outlook onto the Google calendar that stayed empty.
File → Save Calendar / Google Import & export was a snapshot — copies are kept corrected as the originals change.
OGCS stopped when the Windows PC slept — Google and Outlook notify Keeper.sh on Pro, so a copy can land while the laptop is shut.