For each text message, there is a 160 character limit. If you send one text message that is 160 characters or less, you will be charged only one credit for that message.
Some people are confused as to why when they send a message, they see a 450 limit (view picture)
-Character count is how many letters, numbers etc are in your message. Watch the character count. Once you go over 160 characters, say for example 180, that will count as TWO credits.
-Where it is highlighted "Limited to 450", that is the finall number of characters that can be sent for messages. So a 450 limited message would amount to 3 text messages (160+160+130=450), resulting in 3 credits.
(NOTE- In Canada, the limit is 140 characters per credit!)