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Black Friday Marketing SMS: Calculate SMS and LMS Byte Limits to Reduce Bulk Messaging Costs

2026-09-28 · 4 min read

Black Friday Marketing and Text Messaging Costs

November Black Friday represents the most critical sales window of the year for e-commerce stores and online retailers worldwide. To highlight seasonal promotions, flash deals, and exclusive discount codes, businesses dispatch high volumes of promotional text messages to their customer databases. Because messaging platforms bill on a per-message basis, even minor increases in message length can accumulate rapidly into substantial marketing overhead.

Telecommunication networks and messaging service providers categorize outbound text messages into short message service (SMS) and long message service (LMS) based on data payload measured in bytes. Standard SMS messages are restricted to a maximum payload of 90 bytes, whereas LMS accommodates extended text payloads up to 2,000 bytes. When a promotional text exceeds the 90-byte boundary by even a single byte, the transmission system automatically upgrades the dispatch from SMS to LMS.

LMS transmissions typically cost three to four times more per recipient than standard SMS messages. For an e-commerce merchant sending promotional notifications to tens of thousands of subscribers, an accidental tier upgrade caused by a trailing space or unnecessary punctuation mark can multiply campaign delivery costs by 300% to 400% without adding meaningful promotional value. Careful byte management during the copywriting stage is therefore essential for protecting marketing margins.

2-Byte Encoding Standards and Byte Calculation

Understanding how character encoding converts text into data bytes is the first step toward effective messaging budget control. Under standard telecommunications encoding conventions, standard ASCII characters—including basic English letters, numerals, and standard spaces—consume 1 byte of storage each. In contrast, multibyte characters such as Korean, Chinese, Japanese (CJK) scripts and certain specialized formatting symbols occupy 2 bytes per character in regional gateways.

Because the standard SMS boundary is fixed at 90 bytes, a message written entirely in 2-byte characters can accommodate a maximum of only 45 characters. Moreover, commercial marketing regulations frequently mandate the inclusion of specific compliance components, such as business identifiers, toll-free unsubscribe numbers, and tracking links. Once these mandatory elements are incorporated into the message body, the actual space available for promotional copy often drops to approximately 20 two-byte characters.

Manually estimating byte counts based on character counts alone frequently leads to costly dispatch errors because mixed scripts, line breaks, and punctuation consume varying byte quantities. When drafting marketing copy, using Character Counter to check real-time byte sizes with accurate 2-byte CJK calculations ensures your message stays within limits. Verifying both character count and byte weight simultaneously prevents unexpected tier conversions before campaigns are loaded into messaging dispatch consoles.

Managing Byte Headroom with Character Limit Controls

Delivering compelling promotional offers within a strict 90-byte limit requires disciplined copywriting that eliminates redundant adjectives and condenses phrasing without sacrificing clarity. Marketers must convey the core value proposition—such as discount percentages, coupon codes, and expiration deadlines—using direct and actionable language. Every unnecessary modifier or repeated punctuation mark risks pushing the payload past the SMS threshold.

While refining your text, enabling the character limit option in Character Counter and setting a 90-byte cap lets you track remaining capacity with an intuitive progress bar. This visual indicator provides immediate feedback as you edit, allowing you to see exactly how much byte headroom remains as you insert promotional links and compliance notices. By balancing text length against byte allocations in real time, copywriters can fine-tune concise SMS alerts or manage extended copy up to the 2,000-byte LMS ceiling with equal precision.

Real-time byte tracking also assists in evaluating alternative phrasing options before final approval. For instance, shortening full URL strings with custom branded short links or substituting verbose introductory greetings with concise action verbs can free up several bytes. This reclaimed space can then be allocated to essential call-to-action directives or specific promotional deadlines, ensuring that every byte spent contributes directly to recipient conversion.

Importance of Pre-Send Verification for Bulk Campaigns

Thorough pre-send validation is a non-negotiable quality assurance step in high-volume promotional messaging. Marketing automation systems often insert dynamic personalization variables—such as recipient names, localized store locations, or individualized discount vouchers—into the message template at the moment of dispatch. Because recipient names and custom parameters vary in length, copywriters must build an adequate byte safety margin into the baseline template.

Failing to account for variable substitution lengths can cause messages sent to recipients with longer names to cross the 90-byte threshold unexpectedly, triggering partial LMS billing across a substantial portion of the recipient list. Establishing a standard operating procedure where templates are validated against maximum variable lengths prevents these hidden cost overruns. Checking payload size with Character Counter before dispatching bulk messages helps you optimize text length and run cost-effective campaigns within budget.