How Calendar Subscriptions (actually) Work

... and why your subscribers' calendars may be outdated.

Your subscribers click Add to Calendar on Stanza and—like magic—events show up in their calendar. No extra effort, no manual updates. It just works.

Or does it?

If you're hearing from subscribers asking:

• 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: Subscribing = Adding a Link

When adding a calendar to Google, Apple, or Outlook, it's 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. Calendar apps 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 a calendar, iCal feeds are dynamic—meaning if an event changes (like a rescheduled game or a venue update), subscribers' calendar appa request the latest version from Stanza’s servers. However, the timing of those updates isn’t instant—it depends on how often calendar apps decide to check in.

Step 2: Calendar Apps 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 the app decides to refresh it—and that varies widely:

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

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

Step 3: The Invisible Handshake Between Servers

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

1. The 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. The calendar app processes those updates. It removes old events, adds new ones, and updates times/descriptions as needed.

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 they 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 the calendar app, not the source of the events.

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

Have feedback? Email us directly at founders@stanza.co

On Stanza, anyone can create, discover and share event calendars. Getting started is easy. Set up your calendar in just a few minutes.