Understanding SMS credit calculation

Overview

Because of carrier requirements to append messages like Text STOP to stop to your SMS campaigns and automations for certain contacts, the credit count in the SMS builder is not an exact representation of how much your message will cost.

Read on to learn how SMS credit totals are estimated and how emojis can drastically increase the cost of your message.

Credit estimation

The credit counter is an estimate, not your message's final cost.

Wireless carrier guidelines require Sendlane to append a message reading Text STOP to stop to contacts who use AT&T, have a Canadian phone number, or are receiving an SMS message for the first time regardless of carrier or country. The process of determining who needs that message and who doesn't is handled by the various mobile carriers, not Sendlane. This means that the credit count you see in the SMS message builder is not an exact "invoice" of the cost of the message.

Including images or other files converts your message from SMS to MMS, which costs roughly three times as an SMS message.

How emojis affect the cost of a message

Use emojis with care; inserting an emoji causes your message's character count to double.

Characters in the ASCII format (A - Z, a - z, 0-9, spaces, and most common punctuation) are 8 bits each. Inserting an emoji into an SMS message removes ASCII formatting and causes all characters to use more bits (roughly 16 bits each).

If your message is Flash sale today only!! your message will equal 8 bits x 23 characters for a total of 184 bits. If your message is 🎉 Flash sale today only!! each character now requires roughly 16 bits; 16 bits x 23 characters equals a total of 368 bits. Adding a single emoji roughly doubles the size of every character in the message, additional emojis after the first take up the same amount of space as any other character. The message 🎉🎉🎉 Flash sale today only!! is 16 bits x 25 characters for a total of 400 bits.

TL;DR, adding even a single emoji greatly increases the size of your message, so take care when deciding which messages really need them.