What is the standard SMS character limit?

The standard single SMS text message limit is 160 characters when using the GSM-7 alphabet. If a message contains non-GSM characters (such as emojis or accented symbols), the limit drops to 70 characters (UCS-2 Unicode).

Why does adding an emoji decrease my SMS limit to 70 characters?

Standard telecom networks use 7-bit encoding (GSM-7). Emojis require 16-bit encoding (UCS-2 / UTF-16), which takes more data per character, reducing the single message capacity from 160 to 70 characters.

How do multi-part concatenated SMS segments work?

When an SMS exceeds the single message limit, carriers split it into segments with a 6-byte User Data Header (UDH). In GSM-7, multi-part messages contain 153 characters per segment. In Unicode, multi-part messages contain 67 characters per segment.

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SMS Character Counter & GSM-7 vs. Unicode Segment Guide

Are your text messages getting split into multiple expensive segments? Our SMS Character Counter tests your text messages in real time, detecting whether your content uses standard GSM-7 7-bit encoding or switches to UCS-2 Unicode (16-bit).

GSM-7 vs. Unicode SMS Segment Breakdown Table

Encoding Type	1st Single Message	Multi-Part (Segment 2+)	Characters Supported
GSM-7 (Standard)	160 Characters	153 Characters / part	Basic English (A-Z, a-z, 0-9), basic symbols, Greek letters.
UCS-2 (Unicode)	70 Characters	67 Characters / part	Emojis (🚀, ✨), Arabic, Cyrillic, Chinese, Japanese, accented symbols.

Why Did My SMS Split into 2 Messages for 1 Emoji?

Standard mobile networks (Twilio, AWS SNS, Vonage, Sinch, Verizon, AT&T, Vodafone) only allow 1,120 bits per SMS packet. When you type in plain English, each character consumes 7 bits (allowing \(1120 / 7 = 160\) characters).

The moment you insert a single emoji or special curly quote, the entire message shifts to 16 bits per character, cutting your total capacity to \(1120 / 16 = 70\) characters!

Frequently Asked Questions (FAQ)

❓ What is a concatenated (multi-part) SMS?

When a text message exceeds 160 GSM characters (or 70 Unicode characters), telecom carriers join multiple SMS parts together using a User Data Header (UDH). Each segment is billed as an individual message.

❓ Which characters trigger Unicode mode?

Curly smart quotes (“ ” ‘ ’), emojis (😀), accented characters outside the GSM table, and non-Latin alphabets immediately trigger Unicode mode.