SMS Character Limit: How Many Characters Can a Text Message Hold?

The character limit for SMS messages is 160 characters if the message uses the GSM-7 alphabet, or 70 characters if it switches to Unicode (UCS-2) encoding. Both numbers come from the same 140-byte SMS payload defined in the 3GPP standards — GSM-7 fits seven bits per character, Unicode needs sixteen.

How many characters fit in one SMS?

One SMS fits 160 characters in GSM-7 encoding or 70 characters in Unicode (UCS-2) encoding. Both limits trace back to the same technical ceiling: a single SMS payload is capped at 140 bytes, or 1,120 bits, by the SMS message-format standard.

GSM-7 is the default SMS alphabet, and it packs each character into 7 bits instead of a full byte. That gives 1,120 ÷ 7 = 160 characters. Unicode (UCS-2), used for scripts and symbols GSM-7 doesn't cover, needs 16 bits per character, so the same 1,120-bit payload only holds 1,120 ÷ 16 = 70 characters. These numbers come from the SMS alphabet and message-format standards, 3GPP TS 23.038 and TS 23.040.

Why does the limit drop from 160 to 70?

The limit drops to 70 characters as soon as a message contains even one character that isn't in the GSM-7 default alphabet — the network then encodes the entire message as 16-bit Unicode instead of 7-bit GSM-7, not just the one character that triggered it.

Common triggers include:

• Emoji of any kind

• Urdu, Arabic, and other non-Latin scripts

• Chinese, Japanese, and Korean characters

• "Smart" curly quotes, em dashes, and ellipses that word processors insert automatically in place of straight quotes and hyphens

GSM-7 also has an extension table for characters such as €, {, }, [, ], ~, ^, and |; these stay within GSM-7 — they don't trigger Unicode — but each one needs an escape sequence, so it uses 2 character slots instead of 1 (3GPP TS 23.038).

Accented Latin letters are a separate, common trap. Basic accented letters such as é, à, ü, ò, and ñ are part of the GSM-7 default alphabet, so they don't force the switch. But á, í, ó, ú, â, ê, and ô are not in the GSM-7 table — typing even one of them switches the whole message to Unicode, which catches out a lot of Spanish and Portuguese senders.

Why do multipart parts hold 153 or 67 characters?

Multipart parts hold fewer characters — 153 in GSM-7 or 67 in Unicode — because each part needs a small User Data Header (UDH) that tells the receiving phone how to reassemble the parts in the correct order.

Once a message goes over 160 GSM-7 characters or 70 Unicode characters, the network splits it into linked SMS parts, known as concatenated SMS. The UDH that links those parts together has to fit inside the same 140-byte payload as the text, so each part gives up part of its character budget to make room for it, leaving 153 GSM-7 characters or 67 Unicode characters for the message itself in every part (3GPP TS 23.040). A gateway or carrier typically bills each part as a separate message, so it's worth estimating how multipart messages affect SMS cost before you send a long one.

What does SMS stand for and why does length affect cost?

SMS stands for Short Message Service, the text-messaging feature built into GSM and other mobile networks. Its name reflects the original design — a short, fixed-length message — and that same fixed length is exactly why character count still affects delivery and cost today.

A 161-character GSM-7 message, or a message that would have fit in one Unicode part at 70 characters but runs one character over, turns into two billed message parts instead of one, even though the reader experiences it as a single text. Adding a single emoji to an otherwise plain message has a similar effect: it switches the encoding to Unicode and can push a message that would have fit in one GSM-7 part into two Unicode parts. For marketing, OTP, and notification sends, where wording is fixed and volume is high, this difference adds up fast. See more SMS basics guides for related topics.

How do I count SMS characters before sending?

The reliable way to count SMS characters is to run the exact text through a counter that applies the same GSM-7/Unicode rules as the network, rather than counting characters by eye or trusting a word processor's count.

You can check your message's character count and part split before you send anything. It flags whether your message is using GSM-7 or Unicode encoding, shows the exact character count against the relevant limit, and tells you how many parts it will split into — so you can catch a stray emoji or curly quote before it doubles your message count.

Where do I get an online SMS sender or gateway?

Two real starting points, with no affiliation to each other: check whether your operator offers a business or bulk SMS product, since the options and setup vary by operator and country; and well-known SMS API platforms such as Twilio, which many businesses use to send SMS programmatically from their own applications.

WaSMS is run by the same team as this site. It offers WhatsApp, plus SMS through your own Android phone, as another option if you'd rather send from a phone you already own than set up a carrier or API contract — see wasms.net for details.

Check your message's exact character count and part split before you send your next message or campaign.