Why a text is 160 characters, and what a long one costs

Where 160 comes from

A text message is a small, fixed-size packet. Twilio's glossary explains that the original standard "limited a single SMS message to 140 bytes in length." The basic phone alphabet, called GSM-7, uses 7 bits for each character instead of 8. Do the division and 140 bytes hold exactly 160 characters.

That alphabet is small. Twilio describes it as "the original assignment of 128 alphanumeric characters": the English letters, digits, common punctuation and a handful of accented letters. It was designed for short notes between phones, long before anyone sent a text back after a missed call.

What happens when you go over

The network does not refuse a long message. It cuts it into parts and sends each one separately. But every part now needs a small label so the receiving phone can put them back in order. Telnyx's documentation says "a 6-byte header (User Data Header, or UDH) is added to each segment for reassembly, reducing the usable space."

That label takes the room of seven characters. So the numbers change:

• Up to 160 characters: 1 part
• 161 to 306 characters: 2 parts of up to 153 each
• 307 to 459 characters: 3 parts

Notice the trap at 161. One character over the limit doubles the cost of the message. Telnyx puts a ceiling on it too: "Maximum: 10 segments per message." If you are writing your own wording, the templates page shows the character count of each sample.

The emoji problem

Anything outside the basic alphabet cannot be sent in the 7-bit format. The message has to switch to a wider format (called UCS-2 or UTF-16) that uses 16 bits for each character. The packet is the same size, so far fewer characters fit. Telnyx gives the figures: such messages "fit 70 characters in a single segment, or 67 per segment when concatenated."

The part that surprises people is that the switch applies to the whole message. In Telnyx's words: "A single non-GSM-7 character (like an emoji or curly quote) switches the entire message to UTF-16."

So a friendly 150-character text is one part. Add one smiley and the same text is three parts, because 151 characters now have to fit in pieces of 67. Twilio's glossary gives a similar example: a 140-character message with one character outside the basic set becomes two segments, and removing that one character avoids the second.

If you want to see what unanswered calls are worth before you decide how much to spend on texts, the missed calls calculator works it out from your own numbers.

The characters that catch people out

Emojis are the obvious ones. These are less obvious, and all of them come from the sources below:

• Curly quotes and apostrophes. Word processors and phones swap straight quotes for curly ones. Twilio's glossary notes that this alone drops the limit from 160 to 70. If you paste wording from a document, retype the quotes.
• Long dashes. Telnyx lists them next to curly quotes as characters its "smart encoding" option swaps for plain ones. Type a hyphen.
• Brackets and braces. A few characters are in the basic alphabet but need an "escape" in front. Twilio says these "count as two characters," and gives { and ] as examples. They do not switch the format, but they use two places each.

A plain apostrophe, a period, a question mark, a dollar sign and an at sign are all safe. Our templates use only safe characters.

What a long text costs

Providers charge for parts, not for messages. Telnyx: "You are billed per segment, so understanding encoding is key to controlling costs." Twilio's glossary says the same about its own billing. Plans that include a monthly number of texts, ours included, count the same way: a two-part message uses two texts from the allowance. Our allowances are counted per part for that reason.

The customer usually never knows. Phones stitch the parts back together and show one message. You see the difference only on the bill, or when a monthly allowance runs out sooner than you expected.

For a missed-call text this matters more than it looks. The message goes out many times a month, so one stray curly quote in the wording triples the count of every single one.

How to keep a business text to one part

1. Say who you are in the first few words. The caller may not have your number saved.
2. Ask for one or two things, not five: the address and what is wrong.
3. Keep the opt-out line short. "Reply STOP to opt out" is 22 characters.
4. Type it plainly. Straight quotes, hyphens, no emoji. Do not paste from a document.
5. Count it with the longest business name you might use. The name is part of the 160.

That is the method behind our own wording: each message in the template library fits in one text for a business name of up to 30 characters, and the app's preview tells a business how many parts its wording uses before it is saved. Registration is the other thing to sort out before any business text goes out; see what A2P 10DLC is.

Sources

• Twilio glossary: what is the SMS character limit (140 bytes, 160 and 153, 70 and 67)
• Twilio glossary: what is GSM-7 character encoding (128 characters, escape characters count as two)
• Telnyx developer documentation: message encoding (header, one character switches the format, 10 segments, billed per segment)

All three pages were read on October 9, 2026. Providers differ in details such as the maximum length; your provider's page is the final word. We are not affiliated with Twilio; NewFrontDesk's texting will run through Telnyx and is not live yet.