THE TEXT MESSAGE, EXPLAINED

160 characters,
and why.

A limit set at a typewriter in the 1980s.

SMS, the short message service, was squeezed into the signalling spare room of early digital mobile networks. Its 160-character limit came from counting real sentences, and it still shapes how your phone splits and counts a text today.

SINCE 1992 Merry Christmas, sent from a PC

Count your text

Hands holding a plain smartphone showing an empty message bubble, in a living room with soft fairy lights behind — AI-generated image, not a photograph of a real person or place.

160 plain letters
70 with an emoji
Long texts travel in parts
The rules behind every text

THE SHORT ANSWER

Small by design,
split when long.

A text is 140 bytes of payload.
What fits depends on the alphabet your message needs.

THE LIMIT

Counted on a typewriter

Friedhelm Hillebrand typed out sentences and found 160 characters was enough for a sentence or a question, partly from the typical length of postcards and telex messages.

Count your text

THE ALPHABET

Seven bits a letter

The default GSM 7-bit alphabet fits 160 characters. Switch to 16-bit characters, as many emoji and scripts need, and a text holds 70.

See the numbers

THE NETWORK

Riding the signalling

Messages were limited so they could fit into the existing signalling formats of the network, which is why they started so short.

Text 999

COUNT YOUR TEXT

What is in
your message?

Pick what you are sending to see how many characters fit in one SMS. The bar shows how quickly you use up a message.

Text check

Choose a messagePlain letters and numbersA long plain messageA short text with an emojiA long text with an emoji

Plain letters and numbers160 per text

The GSM 7-bit alphabet, which every GSM handset must support, fits 160 characters in a single message.

A long plain message153 per part

Longer texts are sent as several messages, each starting with a header that says how to reassemble them, leaving 153 characters per part.

A short text with an emoji70 per text

Characters outside the 7-bit set need the 16-bit UCS-2 or UTF-16 alphabet, which allows 70 characters in one message.

A long text with an emoji67 per part

With 16-bit encoding and the segment header, each part of a long message carries 67 characters.

Source: Wikipedia, SMS (message size and concatenated SMS sections). One message carries 140 bytes of user data.

Figures from the SMS standard as summarised in the Wikipedia SMS article. Phones and apps may display counts differently.

TWO NUMBERS WORTH KNOWING

From one test
to a Christmas rush.

One figure on the design,
one on how big texting became in the UK.

160

Characters Hillebrand judged enough

Working on mobile standards in the mid-1980s, when bandwidth was very limited, he counted characters in typed sentences and settled on 160.

THE DESIGN · NPR

205m+

Texts sent in the UK on Christmas Day 2006

By the end of 2000 the average had reached 35 messages per user per month, and on Christmas Day 2006 more than 205 million were sent in the UK.

UK PEAK · WIKIPEDIA

At first, UK networks only allowed texts to people on the same network, which limited how useful the service was.

TEXTING 999 IN THE UK

Register first,
not in a crisis.

Deaf, hard of hearing and speech-impaired people can text 999 through the emergencySMS service run by Relay UK. It only works once your mobile is registered.

Text register to 999
Read the automatic reply in full, then reply yes to finish registering.
Wait for the confirmation
You get a text saying your mobile is registered. Register again if your number changes.
Say which service and where
Ambulance, police, fire or coastguard, what is happening, and a precise location.
Use it when you must
Relay UK says it takes longer than a voice 999 call or the 18000 relay service.

A mobile phone mast against a pale evening sky above rooftops — AI-generated image, not a photograph of a real person or place.

An old green manual typewriter with a blank sheet of paper and seaside picture postcards on a wooden desk — AI-generated image, not a photograph of a real person or place.

THE FIRST TEXT

Sent from a PC,
read at a party.

On 3 December 1992 Neil Papworth, a 22-year-old test engineer, sent Merry Christmas from a personal computer to a colleague's handset. NPR reports it arrived during the staff Christmas party.

The idea was older. NPR credits the Finnish engineer Matti Makkonen with proposing it at a conference in the 1980s, and IIT Madras's Shaastra magazine notes that Hillebrand himself traced text communication back to Morse telegraphy and telex.

Questions

Questions people ask

Why are texts limited to 160 characters?

Messages had to fit the existing signalling formats of the network, giving 140 bytes of data. With a 7-bit alphabet that is 160 characters, a length Hillebrand judged enough for most short messages.

Why does one emoji shorten my text?

Emoji and many non-Latin characters are not in the GSM 7-bit alphabet, so the whole message switches to 16-bit encoding, which fits 70 characters.

What happens if I type more than 160 characters?

The phone sends a concatenated message in several parts. A header in each part tells the receiving phone how to join them, so each part holds 153 plain characters.

When was the first text sent?

On 3 December 1992, when Neil Papworth sent Merry Christmas to colleague Richard Jarvis's handset over a UK mobile network.

Can I text 999 in the UK?

Yes, if you are deaf, hard of hearing or speech-impaired and have registered your mobile with emergencySMS by texting register to 999. Relay UK says to register in advance, not in an emergency.

160 characters,
and why.