A standard SMS can contain up to 160 characters, depending on the alphabet used in your SMS. 

For a concatenated SMS the costs of each extra SMS will be charged; however, not all countries support concatenated SMS and might handle multi-part SMS in different ways. You can check if the country you want to send messages to does or doesn't support concatenated SMS in our country info & restrictions.

You can read more about the characters in an SMS message here.