Understanding Special and Non-Special Characters for SMS

The standard number of characters available for an SMS is 160.

However, the use of special characters and emojis reduces this limit to 70.

What are Non-Special Characters?

non special characters list

What are Special Characters?

Any character not listed in the table above + emojis are special characters.

Note: Most non-special characters use 1 bit to be encoded and hence are counted as 1 character. Some non special characters such as the vertical bar ( | ) and the Tilde ( ~ ) use 2 bits to be encoded and hence are counted as 2 characters.
Special characters and Emojis use more than 2 bits to be encoded and hence are counted accordingly. The emoji "👩‍👧‍👦" uses 8 characters.

How are credits calculated for non-special characters?

Most non-special characters fall under the GSM-7 encoding mechanism which means each character takes up 1 bit to be encoded.

One message segment allows you 160 characters. An SMS containing the message “ Hi this is a simple text message.” has 33 characters and hence has used up 33 out of the available 160 characters for one message segment.

However, if I add a character like a “|” (vertical bar), it will take up an extra 2 characters as it takes 2 bits to be encoded. Hence, the modified message “ Hi this is a simple text message.| ” will use 35/160 characters.

As this message uses only 1 message segment, only 1 credit will be utilized.

What happens when I exceed the 160-character limit?

As soon as the characters go above 160 characters, the following characters will become part of the second message segment.

Since 2 message segments will be used to send the message, the number of credits used will be 2.

Note The second message segment will only have 153 characters because 7 of the 160 characters will be used for a header in the backend. This header will help the carrier identify that the message segments need to be sent together.

How are credits calculated for Special characters?

Special characters fall under the UCS-2 encoding mechanism. In this mechanism the special characters take up 2 or more than 2 bits to be encoded.

With the UCS-2 encoding one message segment equals 70 characters. For example,

“ Hi this is a simple text message 🙂”

will use 35 out of the 70 characters available for one message segment. The presence of the emoji 🙂changed the available characters to 70.

As this statement only uses 1 message segment (under 70 characters), one credit will be used for this message.

What happens when I exceed the 70 character limit?

If the above message was modified to

“Hi this is a simple text message 🙂Please confirm if you have received this message.”

This statement now has 84 characters which has exceeded the 70-character limit. The characters following this limit will now be part of the second message segment. The message will now cost you 2 credits, for 2 message segments

Note The second message segment will only have 67 characters because 3 of the 70 characters will be used for a header in the backend. This header will help the carrier identify that the message segments need to be sent together.

Any unicode character is considered special, even if it looks similar to a non-special character. Let’s use the example of double quotation marks.
This is the non-special character: “
These are special characters: «, “, ‟, ❝,〝, “

Summary

Non-Special Character Length	Special Character Length	Segments (in numbers)	Charged as
0 – 160 characters	0 – 70 characters	1	Single credit
161 – 306 characters	71 – 137 characters	2	Two credits
307 – 459 characters	138 – 204 characters	3	Three credits
460 – 612 characters	205 – 271 characters	4	Four credits
613 – 765 characters	272 – 338 characters	5	Four credits
766 – 918 characters	339 – 405 characters	6	Four credits
919 – 1,071 characters	406 – 472 characters	7	Four credits
1,072 – 1,224 characters	473 – 539 characters	8	Four credits
1,225 – 1,377 characters	540 – 606 characters	9	Four credits
1,378 – 1,530 characters	607 – 673 characters	10	Four credits