Under the message box Sprwt shows N Characters Remaining, Total N Message(s), the total character count and Cost $X/per SMS. A text is split into carrier segments; each segment costs the per-message rate. Standard (GSM) characters allow 160 characters in a single segment, but non-GSM characters such as ñ, à, ö, *, ~ or emoji switch the whole message to a smaller per-segment limit, so the same text can need more segments — hence the warning "Using non-GSM characters may increase the cost by reducing the character limit per message". Merge fields are counted at their placeholder length in the editor but expand per recipient at send time, which is why the confirmation recommends keeping an extra 20% balance. The actual charge uses the segment count reported by the carrier when available.