Clock app alarms vs Tellendar: which alarm for an appointment?

Updated October 8, 2026

The iPhone Clock app rings in silent mode and with Do Not Disturb on. But a Clock alarm has no date, only a time and days of the week. For a specific appointment, you have to create it the day before and delete it afterwards. Tellendar puts the same iOS alarm directly on the event in your calendar.

What the Clock app does well

The iPhone alarm clock is the only alarm available without installing an app. It rings at the set time, in silent mode and with Do Not Disturb on. The switch on the side of the iPhone has no effect on it. That is what Apple says in its support pages.

When you create an alarm, Clock offers four settings: Repeat (days of the week), Label (the name shown when it rings), Sound, and Snooze, with a snooze duration you can choose. You can also ask Siri to set an alarm.

Where it falls short for appointments

• No date. A Clock alarm is set to a time, not a day. You can repeat it on Mondays or Thursdays, but you cannot pin it to November 14. For an appointment three weeks away, you have to remember to create it the day before.
• Nothing ties it to your calendar. If the appointment moves, the alarm stays where it was. If the appointment is cancelled, the alarm rings anyway.
• One alarm per line. To be warned the evening before and again one hour before, you need two alarms, with two labels to type.
• Past alarms stay. Once the appointment is over, the alarm stays in the list, switched off. After a few weeks the list contains "Dentist" and "Garage" alarms you can no longer match to an appointment.
• One kind of repeat. Clock repeats by day of the week. A class every other Thursday, or a meeting on the first Monday of the month, cannot be set.

Using the Clock app anyway

If you only have the occasional appointment, Clock is enough. Here is the safest way to use it.

1. Put the appointment in your calendar as usual.
2. The day before, open Clock, tap "Alarms", then the "+" button. Set the time you want to be warned at, for example one hour before.
3. Under "Label", type the name of the appointment. That is what shows when the alarm rings.
4. Leave "Repeat" empty so the alarm rings only once.
5. After the appointment, swipe left on the alarm to delete it.

You can also tell Siri "Set an alarm for 2:45 PM". Then give it a label, or you will not know which appointment it is for.

What Tellendar changes

Tellendar is a calendar app for iPhone. Every event can have its own alarms, and they are real iOS alarms, the same kind as the Clock app's: they ring in silent mode, with Do Not Disturb on, and even if the app is closed. The difference is that they are attached to the appointment.

• One sentence is enough. Type or dictate "Dentist November 14 at 3 PM, alarm 1 hour before". Tellendar creates the event and the alarm. The name of the appointment shows when it rings.
• The alarm follows the appointment. It is counted from the start of the event. Move the appointment and the alarm moves with it. Delete it and the alarm goes away.
• Several alarms, in one sentence. "Alarm the day before and 1 hour before" puts two alarms on the same event.
• Recurring appointments. Every other Thursday, the first Monday of the month: each occurrence gets its alarm. Tellendar schedules them as it goes, three months ahead.
• Nothing to delete. A past alarm disappears. There is nothing to switch off or delete.

When the alarm rings, you stop it, or tap "Snooze 10 min" to have it ring again. You pick the sound in Tellendar's settings: the iOS one, or one of the app's seven, whose volume rises gradually over about twelve seconds.

When to keep the Clock app

Tellendar is not an alarm clock. For waking up in the morning, for the sleep schedule in the Health app, or for an alarm with no date ("every day at 6 PM, medication"), Clock remains the right tool. The two apps complement each other: Clock for alarms at a fixed time, Tellendar for appointments.

Frequently asked questions