What is an SMS segment? Character limits, emoji and cost

An SMS segment is the unit a text message is sent and billed in. One segment holds up to 160 characters when every character comes from the basic GSM-7 set, or 70 when the text has an emoji, a curly quote or another character outside it. Longer texts split into parts of 153 or 67 characters, each one charged.

This guide explains where those numbers come from, why a short text can still count as two, which characters cause it, how the opt-out line adds to the count, and how to write texts that stay inside one segment. For ready-made wording, see our follow-up text templates.

What is an SMS segment?

A segment is one standard text message as the network carries it. The technical standard for SMS sets a fixed size for each one: "The text messages to be transferred [...] contain up to 140 octets" (3GPP TS 23.040, version 20.0.0, 2026). An octet is one byte, so every segment has the same 140 bytes of room for text.

How many characters fit in those 140 bytes depends on the alphabet, which the companion standard sets out (3GPP TS 23.038, version 20.0.0, 2026):

• GSM-7, the default alphabet, packs each character into 7 bits, so "the message can consist of up to 160 characters".
• UCS-2, the alphabet used for everything else, takes 2 bytes per character, so the message "can consist of up to 140 octets, i.e. up to 70 UCS2 characters".

Your phone shows a long text as one message. The network, and your bill, see the segments underneath it.

How many characters fit in a text message?

The whole text uses one alphabet. If every character is in GSM-7, you get 160; if even one isn't, the whole text switches to UCS-2 and you get 70.

Alphabet	When it's used	One segment	Each part when split	2 parts	3 parts
GSM-7	Only basic letters, numbers and common punctuation	160	153	306	459
UCS-2	Any character outside GSM-7: emoji, curly quotes, many accented letters	70	67	134	201

Split texts lose a few characters per part because each part carries a small header that tells the phone how to put the pieces back together. The standard gives the limit per part as "153 (160-7) characters" for GSM-7 and 67 for UCS-2 (TS 23.040, clause 9.2.3.24.1). It allows up to 255 parts, though a business text rarely needs more than two.

Why does my text show as one message but count as two?

Because the phone joins the parts back together. Each part carries a reference number "so that the receiving entity is able to reassemble the short messages in the correct order" (TS 23.040). The person sees one message; the network delivered two or three, and each is billed.

Three things usually push a text over the line without anyone noticing:

1. One special character. A single curly apostrophe drops the limit from 160 to 70 for the whole text.
2. Fields that fill in long. A template that fits with "Jordan" and "Acme" can spill over with a 14-letter first name and a 30-character company name.
3. The opt-out line. On a first text, it can take more room than your own words. More on that below.

Which characters switch a text to 70 characters?

Any character outside the GSM-7 alphabet. The ones that cause most surprises:

Character	Where it usually comes from	What to use instead
Curly apostrophes and quotation marks	Word processors, phone keyboards with smart punctuation, text copied from a website	Straight ' and " typed in a plain editor
Long dashes (en and em dashes)	Word processors that convert two hyphens	A comma, a full stop or a plain hyphen
The single-character ellipsis	Autocorrect turning three dots into one character	Three full stops
Emoji	The phone keyboard	Words
Letters such as ê, â, á, í, ó, ú and a lower-case ç	Names, and French or Spanish wording	Keep them where they matter, and plan for 70 characters

GSM-7 does include some accented letters, such as é, è, à, ü and ñ, so "café" and "Señor" stay at 160.

Nine characters sit in GSM-7's extension table and count as two each: curly braces, square brackets, the tilde, the backslash, the vertical bar, the caret and the euro sign. The standard says the number of characters "will reduce by one for every instance where the GSM 7 bit default alphabet extension table is used" (TS 23.038). The double braces in a First name field don't count, because the field is replaced by the value before the text is sent.

In practice most emoji take two of the 70 places, so one emoji costs more room than it looks. Some sending systems swap curly quotes for straight ones before sending; type straight quotes anyway, so you never depend on it.

How does the opt-out line change the count?

The opt-out line is part of the text, so it counts toward the segments. Carriers expect clear opt-out instructions, and in Canada every commercial message has to "set out an unsubscribe mechanism" (CASL s. 6(2)(c)). Our guide to STOP and opt-out rules covers the rules behind it.

Textually adds the line registered with the carriers to each text until the person replies:

Msg frequency varies. Msg & data rates may apply. Reply STOP to opt out, HELP for help.

That line is 87 characters, plus 2 for the line break before it, so 89 in all. It leaves 71 characters of your own words for a one-segment text. Once the person has replied, the line comes off and you have the full 160.

Your own words (GSM-7)	Segments before a reply	Segments after a reply
Up to 71 characters	1	1
72 to 160	2	1
161 to 217	2	2
218 to 306	3	2

With an emoji or a curly quote, the line alone is longer than one 70-character segment. A short text with the line becomes 2 segments, and anything over 45 characters of your own becomes 3.

How does length change what you pay?

Each segment is a separate charge, so a two-segment text costs twice a one-segment text. On Textually each segment uses one text, and texts cost 5 cents down to 2.5 cents depending on the size of the bucket you buy, the same for US and Canadian numbers. Replies you receive are free (pricing).

An example, not a forecast: 1,000 people in a three-text sequence, at 4 cents a text (the 2,500-text bucket), if nobody replies.

Each text is	Segments sent	Cost
1 segment	3,000	$120
2 segments	6,000	$240
3 segments (an emoji plus a longer text)	9,000	$360

Real totals are lower, because a reply ends that person's sequence and the later texts never send. The gap between the rows is the part you control with wording.

How do you keep a text to one segment?

Six habits keep most texts in one segment:

1. Write the first texts to 71 characters. Your name, your business, the reason, one question. The person can't see a character count; they can see a long text.
2. Fill every field with the longest real value before you check the length. Sort your list by the longest company name or service and test with that row.
3. Type in a plain editor. Copying from a word processor or a website brings curly quotes and long dashes with it.
4. Leave emoji for later in the conversation. Before a reply, one emoji can turn a one-segment text into three.
5. Use short links on your own domain. A long tracking link can take half a segment. CTIA asks senders to use a link shortener "dedicated to the exclusive use of the Message Sender" (CTIA, 2023), and shared public shorteners get filtered.
6. Split long thoughts into two steps. Two short texts a few days apart cost the same as one two-segment text, and the second never sends if the person answers the first.

What do one-segment texts look like?

Each text below fits in 71 characters with the fields filled in, so it stays at one segment with the opt-out line attached. Swap "Sam" and "Northwind" for your name and business.

First text to a new lead

Hi First name, Sam at Northwind. Is a call this week good?

Follow-up on a quote

Sam at Northwind. Did the Service quote reach you OK?

Appointment reminder

Northwind: see you Date at Time. Reply R to reschedule.

Closing the loop

Sam at Northwind. Should I check back next month instead?

Once the person has replied, you have the full 160 characters, and you can write as you would to a colleague:

Thanks, Jordan. Thursday at 2:30 PM works. I'll send a calendar invite to the email on your form, and you can text me here if anything changes.

For full sequences with waits and reply checks, see the follow-up text templates and the reminder sequences.

Where does Textually fit?

Textually runs multi-step text sequences for teams in the US and Canada, and charges per segment: a monthly platform fee ($99, or $49 at the founding price for the first 1,000 teams), numbers from $10 a month, and texts from 5 cents down to 2.5 cents each, with replies free. You import a list by CSV or paste, push it to a campaign, and write Text, Wait and Condition steps with any column as a field. Each text carries the registered opt-out line until the person replies, STOP and the other opt-out words stop texts at once, and a reply ends that person's sequence and lands in one shared inbox. Texts go out only inside the sending days and hours you set. Read the guide to SMS for sales and customer follow-up for the bigger picture, see pricing, or apply for access.

Questions

How many characters is one text message?

160 characters when every character is in the GSM-7 alphabet, or 70 when the text has any character outside it, such as an emoji or a curly quote. Longer texts split into parts of 153 or 67 characters, each sent and billed as a segment (3GPP TS 23.038 and 23.040).

Do emoji make a text cost more?

Yes, often. One emoji switches the whole text to the 70-character format, and most emoji take two of those places. A 100-character text that would be one segment without the emoji becomes two with it.

Why does my short text count as two segments?

Usually one of three things: a special character such as a curly apostrophe, fields that filled in longer than expected, or the opt-out line. With an 89-character opt-out line attached, anything over 71 characters of your own words becomes two segments.

Do replies count as segments?

They travel as segments on the network like any text. On Textually, replies you receive are free; each segment you send uses one text.

Does a link count toward the character limit?

Yes, every character of the link counts. Use a short link on your own domain, and check the length with the link in place.

Is the limit the same in the US and Canada?

Yes. The 160 and 70 character limits come from the international SMS standards, which apply on both sides of the border. What differs is the price: on each of our plans, a Canadian segment costs one cent more than a US one.