{"id":105582,"date":"2026-10-15T15:04:22","date_gmt":"2026-10-15T15:04:22","guid":{"rendered":"https:\/\/mailrelay.com\/glossary\/sms-character-limit\/"},"modified":"2026-10-15T15:04:25","modified_gmt":"2026-10-15T15:04:25","slug":"sms-character-limit","status":"publish","type":"glossary","link":"https:\/\/mailrelay.com\/en\/glossary\/sms-character-limit\/","title":{"rendered":"SMS character limit"},"content":{"rendered":"\n

An SMS allows up to 160 characters if it uses the basic GSM-7 alphabet. If it includes a character outside that alphabet, such as an emoji or \u00e1, the limit drops to 70.<\/strong> If the text goes over that limit, it is split into several SMS and each part is charged separately.<\/p>\n\n

It looks like a technical detail, but it affects what you pay for every SMS marketing<\/a> campaign. A single \u201c\u00f3\u201d can turn a 150-character message into two SMS.<\/p>\n\n

How many characters can an SMS have?<\/h2>\n\n

The number of characters in an SMS depends on the message’s encoding<\/strong>: the character set the phone uses to send it. There are two:<\/p>\n\n

Encoding<\/th>When it’s used<\/th>Characters in 1 SMS<\/th>Characters per part if split<\/th><\/tr><\/thead>
GSM-7<\/td>Only letters, numbers and symbols from the basic alphabet<\/td>160<\/td>153<\/td><\/tr>
Unicode (UCS-2)<\/td>There is at least one character outside the basic alphabet<\/td>70<\/td>67<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

The rule is all or nothing<\/strong>. A single Unicode character is enough to switch the whole message to Unicode and drop the SMS character limit from 160 to 70.<\/p>\n\n

\"160<\/figure>\n\n

Why does a long SMS have 153 characters per part?<\/h2>\n\n

When a text goes over the limit, the carrier sends it as several SMS and the recipient’s phone puts them back together. So the phone knows how to join them, each part carries an invisible header<\/strong> that takes up space.<\/p>\n\n

That’s why each part loses 7 characters in GSM-7 (from 160 to 153) and 3 in Unicode (from 70 to 67). Here’s what that means in practice:<\/p>\n\n

Text length (GSM-7)<\/th>SMS charged<\/th><\/tr><\/thead>
Up to 160 characters<\/td>1<\/td><\/tr>
161 to 306<\/td>2<\/td><\/tr>
307 to 459<\/td>3<\/td><\/tr>
460 to 612<\/td>4<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

In Unicode, the jumps come sooner: at 70, 134, 201 and 268 characters.<\/p>\n\n

Which characters drop an SMS to 70?<\/h2>\n\n

The GSM-7 alphabet includes unaccented letters, numbers and the most common punctuation marks. It also includes some Spanish letters, such as \u00f1, \u00e9, \u00fc and the \u00bf and \u00a1 marks<\/strong>.<\/p>\n\n

But not all of them.<\/p>\n\n

These are the characters that most often switch an SMS written in Spanish to Unicode:<\/p>\n\n