The original SMS (Short Message Service) protocol has a strict character limit of 160 characters per message. If you type a very long text message on an Android phone, the default Messages app will typically split it into multiple SMS texts and stitch them back together on the recipient’s phone. However, if your message crosses a certain length threshold (usually 3 or more concatenated messages), Android will automatically convert the entire thread into a single MMS (Multimedia Messaging Service) file before sending it.
If you have an older cellular plan that offers unlimited SMS texts but charges you a premium per-message fee for every MMS message you send, this automatic conversion can result in a massive phone bill at the end of the month simply because you sent a long paragraph of text.
You can force your Android messaging app to never upgrade your texts to MMS format.
How to Stop SMS to MMS Conversion (Samsung Messages)
If you are using a Samsung Galaxy phone with the default Samsung Messages app, you can disable the auto-conversion.
- Open the Messages app.
- Tap the three vertical dots in the top-right corner and select Settings.
- Tap on More settings.
- Tap on Text messages.
- Look for the setting labeled Auto combination or Long SMS to MMS (depending on your carrier firmware).
- Turn this toggle Off.
How to Disable on Google Messages
If you use Google’s official Messages app, it relies heavily on RCS (Rich Communication Services) rather than SMS/MMS for long texts. If you are texting someone without RCS, Google Messages does not have a native toggle to stop MMS conversion. To avoid MMS charges:
- Open Google Messages.
- Tap your profile icon and select Messages settings.
- Tap on Advanced.
- Turn on Show characters typed. This will display a character counter next to the send button, allowing you to manually see when you are approaching the 160-character limit, so you can manually break up your texts before Android decides to convert them to an expensive MMS payload.