How Calendar Subscriptions Work (And Why Yours Might Be Outdated Right Now)

You click Add to Calendar and—like magic—events show up in your calendar. No extra effort, no manual updates. It just works.

Or does it?

If you've ever found yourself wondering:

• Why hasn’t this event time changed yet?
• Why does my calendar update instantly sometimes but take forever other times?
• How does this even work?

You’re in the right place. Let’s break it down.

Step 1: When You Subscribe, You’re Actually Adding a Link

When you add a calendar to Google, Apple, or Outlook, you’re not actually downloading anything in the way you might download a PDF or a spreadsheet. Instead, you’re subscribing to a special type of live-updating link called an iCalendar feed (or iCal feed).

Think of it like subscribing to a podcast:

• You don’t download every episode in advance.
• Your podcast app checks for new episodes at regular intervals.
• When a new episode is available, it shows up automatically.

Calendar subscriptions work the same way. Your calendar app checks back every so often to pull in the latest version of the schedule.

What Exactly Is an iCal Feed?

An iCal Feed is a universal way for calendars to share event data. It’s a simple text file that includes:

• 📅 Event details – Name, date, time, location, description
• 🔄 Recurrence rules – Whether an event repeats weekly, monthly, etc.

Unlike manually adding events to your calendar, iCal feeds are dynamic—meaning if an event changes (like a rescheduled game or a venue update), your calendar app requests the latest version from Stanza’s servers. However, the timing of those updates isn’t instant—it depends on how often your calendar app decides to check in.

Step 2: Your Calendar App Decides When to Refresh

Here’s where things get tricky.

Unlike a website, which loads fresh content every time you visit, a calendar only updates when your app decides to refresh it—and that varies widely:

• Google Calendar – Updates ICS feeds every 24-48 hours (yes, that’s a long time).
• Apple Calendar (iPhone/Mac) – Refreshes every 3-24 hours, depending on settings.
• Outlook & Others – Unpredictable, sometimes taking days.

So if an event changes right now, your app might not show that change for another day or two—or even longer. That’s why people sometimes miss last-minute reschedules.

🚨 Key takeaway: If your calendar isn’t updating, it’s not broken—your app just hasn’t checked in yet.

Step 3: The Invisible Handshake Between Servers

When your calendar app does decide to refresh, here’s what happens behind the scenes:

1. Your calendar app pings Stanza's server. It sends a request saying, “Hey, got any updates?”
2. Our server responds with the latest version. If events have changed, you get the newest details.
3. Your calendar app processes those updates. It removes old events, adds new ones, and updates times/descriptions as needed.

This is also why you can't edit events in a subscribed calendar—your app will override any edits once it downloads the latest batch of events.

Step 4: The Problem With Silent Updates

Because updates happen invisibly in the background, most people don’t know when their calendar last refreshed. That’s why you sometimes see outdated event times or missing details.

We think there’s a better way.

That’s why Transparent Updates now show you exactly when your calendar last refreshed—so you never have to wonder if you’re looking at old data.

The Bottom Line

Calendar subscriptions are incredibly useful, but they’re not real-time. The speed at which your events update depends entirely on your calendar app, not the source of the events.

So if your schedule changes and you don’t see it right away, now you know why.