Learn how SMS reminder usage is calculated, how message length and characters affect segments, and how to optimize your reminders to match your subscription plan.
Each SMS segment sent counts as one reminder.
A message may use more than one reminder depending on:
You can estimate reminder usage using the Reminder Calculator in your account settings.
Each text message is sent in segments.
One segment = one reminder consumed.
Even if a message appears as a single text on a phone, it may actually be sent using multiple segments.
Example:
The number of characters allowed depends on the character format used in the message.
If your message only contains standard characters, the limit is:
160 characters per segment
If your message contains Unicode characters, the limit becomes:
70 characters per segment
Unicode characters include:
If even one Unicode character is present, the entire message must be sent using Unicode format.
Modern phones support SMS concatenation.
This means longer messages are:
Previously, these messages would appear as multiple texts sent in rapid succession.
Reminder usage is based on the number of SMS segments required to send your message.
Even if your message appears as a single SMS, it may require multiple segments, meaning multiple reminders will be consumed.
This mirrors how SMS providers charge for message delivery.
Your account includes a Reminder Calculator that estimates how many reminders your message will consume.
You can find it in:
Account Settings
As you type your message, the calculator shows:
You can also view reminder usage in the Google Calendar add-on by opening an appointment after saving your reminder message.
Note: The add-on calculates reminder usage after the message is saved, not in real time.
Reminder messages may include dynamic fields that automatically insert appointment data.
These fields affect the total character count.
Because titles and addresses vary in length, the exact reminder usage may differ for each appointment.
You can open the appointment in the app to see the exact number of reminders that will be consumed.
Including a URL or website link can significantly increase the character count.
Long URLs may cause your message to use multiple SMS segments, increasing reminder usage.
If Appointment Confirmations are enabled, an additional message is automatically appended to your reminder.
Example appended message:
Confirm or cancel:
https://www.smsreminder.co/confirmation/ZwhFHBRK2wq9sM6KGME_M
This appended message uses 81 characters, which is included in the character limit calculation.
The Reminder Calculator automatically accounts for this when estimating reminder usage.
Most businesses see the best results with one reminder 24 hours before the appointment and a second reminder on the same day.
Yes. SMS reminders are one of the most effective ways to reduce no-shows because text messages are seen quickly and are harder to overlook than email.
A common best practice is to send one reminder 24 hours before the appointment and another 2 to 3 hours before the scheduled time.
SMS is generally more effective for appointment reminders because it is immediate, visible, and more likely to be opened quickly.
A good appointment reminder should include the client’s name, appointment date, appointment time, location or meeting link, and a simple way to confirm or reschedule.