SMS messages may look simple, but their length can directly affect campaign costs and delivery performance.

Businesses often calculate SMS expenses based on the number of recipients and the price per message. However, one message displayed on a recipient’s phone may consist of several separately billed SMS segments.

The number of segments depends on message length, character encoding, and the symbols used in the text.

For companies sending large volumes of A2P SMS, understanding these factors helps estimate costs accurately and avoid unexpected charges.

How Many Characters Can One SMS Contain?

The standard SMS character limit is often described as 160 characters. However, this applies only to messages using GSM-7 encoding.

SMS supports different character encodings, each with its own limits.

GSM-7 encoding supports standard Latin letters, numbers, and common punctuation. A single SMS can contain up to 160 characters.

Unicode encoding supports a wider range of characters, including Cyrillic, Chinese characters, and emojis. A single Unicode SMS can contain up to 70 code units.

When a message exceeds these limits, it is divided into multiple segments. Each segment reserves some space for technical information that allows the recipient’s device to combine the parts.

For longer messages, the limits are typically:

Encoding Single SMS Each segment of a longer SMS
GSM-7 160 characters 152–153 units
Unicode 70 code units 66–67 code units



The exact limit depends on the method used to combine message segments. Some special characters and emojis also require more than one encoding unit.

What Happens When an SMS Exceeds the Character Limit?

When an SMS exceeds the permitted length, it becomes a concatenated SMS — a message transmitted in multiple parts.

For example, a GSM-7 message containing 300 standard characters requires two segments, while a longer message may require three or more.

The recipient normally sees one complete SMS because the device combines the received segments automatically.

However, billing can work differently. SMS traffic is commonly charged per segment, meaning that one long message may generate several billable units.

This difference becomes particularly important for businesses sending promotional campaigns, service notifications, and other high-volume communications.

How SMS Segmentation Affects Messaging Costs

Consider a retailer preparing an SMS campaign for 100,000 customers.

The original promotional message contains 140 standard GSM-7 characters and fits into one segment.

Now imagine the marketing team adds a smiling emoji 😊.

The emoji changes the message encoding to Unicode. As a result, the message requires three segments instead of one.

Original message With emoji
SMS segments per recipient 1 3
Recipients 100,000 100,000
Total SMS segments 100,000 300,000



That’s 200,000 additional billable segments, assuming per-segment billing.

The actual financial impact depends on the applicable SMS rates and supplier pricing model.

Not every emoji increases the segment count threefold. A short message containing an emoji may still fit into a single Unicode segment. The complete message length determines the final result.

Which Characters Can Change SMS Length?

Emojis are one example of characters that can affect SMS encoding.

Other common examples include smart quotation marks, long dashes, non-Latin alphabets, and certain special symbols.

These characters can appear when content is copied from Word documents, websites, or marketing materials.

Some symbols behave differently. For example, the euro sign (€) belongs to the extended GSM-7 character set. It uses two encoding positions but does not require switching the entire message to Unicode.

Personalized content also deserves attention. Customer names, promotional codes, and dynamic text may increase the message length or introduce characters that change its encoding.

Testing the final message after personalization helps avoid differences between the planned and actual segment count.

Can Long SMS Messages Affect Delivery?

SMS segmentation can influence delivery as well as cost.

The individual parts of a long SMS must reach the recipient’s device to be assembled into the complete message.

If a segment is delayed or fails to arrive, the recipient may experience a delay or receive an incomplete message, depending on the network and device.

This is particularly relevant for time-sensitive communications such as order updates, appointment reminders, and authentication messages.

Delivery reporting also requires attention. Depending on the messaging infrastructure, delivery statuses may be available for individual segments rather than only for the complete message.

Understanding how these statuses are processed helps businesses interpret delivery results more accurately.

How to Avoid Unexpected SMS Costs

A few checks before sending can help businesses manage SMS campaign budgets more effectively.

  1. Check message encoding. Identify whether the text uses GSM-7 or Unicode.
  2. Calculate the segment count. Review how many segments the complete message requires, including personalization.
  3. Review special characters. Pay attention to emojis, quotation marks, punctuation, and non-Latin text.
  4. Test the final content. Check messages after dynamic fields, links, and customer names have been inserted.
  5. Estimate the total campaign cost. Calculate the expected billable segments using the applicable destination rates.

These checks are especially useful for campaigns reaching large audiences across multiple countries.

Managing SMS Costs Across International Markets

SMS length is one of several factors influencing the cost of international A2P messaging. Destination-specific pricing, operator requirements, and traffic characteristics also play a role.

Sempico Solutions operates as an international SMS hub built on its own CPaaS platform, supporting businesses with SMS routing, traffic management, and connectivity across international markets.

For businesses planning large-scale SMS communication, understanding how messages are encoded and segmented provides a more accurate basis for cost planning.

Reviewing message length before sending is a straightforward way to reduce avoidable expenses while keeping communication clear and effective.