Count SMS characters and segments, and see whether your message uses GSM-7 or Unicode encoding.
Characters like € { } [ ] ~ ^ | count as 2.
160 characters for GSM-7 text, or 70 if it contains Unicode characters like emoji or Hindi.
Over the limit it is split into segments of 153 (or 67) characters, and each is billed.
No. Everything is worked out in your browser and nothing you type is sent to a server.