# SMS segment calculator. - Canonical URL: https://www.broadnet.me/tools/sms-segment-calculator - Language: en - Last updated: 2026-10-21 - Publisher: BroadNet (https://www.broadnet.me) - Markdown version of the page above, generated from the rendered page. Free developer tool · runs in your browser Paste a message to see its encoding (GSM-7 or UCS-2), how many SMS segments it will cost, characters left in the current segment, and exactly which characters force the message into double-byte Unicode. Nothing leaves your device. 85 characters Try an example Optional cost estimate Enter your own rate to estimate cost. This uses your number only — BroadNet does not set a price here. Encoding GSM-7 Single-byte alphabet Characters 85 Segments 1 Left in part 75 Single SMS fits 160 chars. Each concatenated part holds 153 (the UDH concatenation header uses 7). The short answer ## What is an SMS segment? An SMS segment is one message unit as it travels over the mobile network. A single SMS holds 160 characters in GSM-7 encoding or 70 in UCS-2. Longer messages are split into concatenated segments of 153 (GSM-7) or 67 (UCS-2) characters each, because a header is added so the handset can reassemble them. Carriers bill per segment, not per message. ### How SMS segmentation works SMS encoding is defined in the GSM 03.38 standard. Every message is sent as either GSM-7 (a 7-bit alphabet, 160 characters per segment) or UCS-2 (16-bit Unicode, 70 characters per segment). A single character outside the GSM-7 alphabet forces the entire message to UCS-2, cutting the per-segment budget by more than half. When a message is longer than one segment, the carrier wraps each part in a User-Data Header (UDH) so the receiving phone can stitch them back together. That header consumes 7 characters of payload per part, which is why concatenated segments shrink to 153 (GSM-7) or 67 (UCS-2). | Property | GSM-7 | UCS-2 (Unicode) | |---|---|---| | Bits per character | 7-bit | 16-bit | | Single SMS | 160 characters | 70 characters | | Per concatenated part | 153 characters | 67 characters | | Alphabet | Basic Latin + limited European set | Any Unicode: Arabic, Cyrillic, CJK, emoji | | Triggered by | Default for supported characters | One non-GSM-7 character anywhere | | Extension characters | Count as 2 (e.g. € { } [ ] ~ \| ^ \) | Count as 1 | ## Frequently asked questions **Why did my message split into multiple SMS?** Your message exceeded the single-segment limit — 160 characters in GSM-7 or 70 in UCS-2. Once you pass that limit the carrier splits the text into concatenated parts of 153 (GSM-7) or 67 (UCS-2) characters each and bills each part separately. **Do emojis cost more?** Yes. A single emoji forces the whole message to UCS-2 encoding, dropping your budget from 160 to 70 characters per segment. A short message that would have been one GSM-7 segment can suddenly become two or three UCS-2 segments once an emoji is added. **What is GSM-7?** GSM-7 is the 7-bit default alphabet defined in the GSM 03.38 standard. It covers basic Latin letters, digits, common punctuation and a small set of European characters, and fits 160 characters in a single SMS. A handful of characters (€ { } [ ] ~ | ^ \) live in the extension table and count as two units each. **What is UCS-2 and when is it used?** UCS-2 is a 16-bit Unicode encoding used whenever a message contains any character outside the GSM-7 alphabet — Arabic, Cyrillic, Chinese, Japanese, Korean, emoji, curly quotes, em-dashes or certain accented letters. It supports every script but only fits 70 characters per single segment. **What is concatenated SMS and the UDH?** Concatenated SMS is how a long message is delivered as several linked segments that the receiving handset reassembles into one. Each segment carries a User-Data Header (UDH) — a short prefix identifying the reference number, total parts and sequence. The UDH consumes 7 characters of payload, which is why concatenated parts hold 153 (GSM-7) or 67 (UCS-2) rather than the full 160 or 70. **Which characters silently force UCS-2?** Smart or curly quotes, em-dashes, the ellipsis character, some accented letters not in the GSM-7 extension table, and any emoji all force UCS-2. These are often inserted automatically by phones and word processors, so a message can switch encoding without you noticing. The calculator above lists the exact characters responsible. **Is this calculator accurate for billing?** It applies the standard GSM 03.38 segmentation rules that carriers use, so segment counts match how most networks bill. Actual charges depend on your provider's per-segment rate and routing. Enter your own rate above to estimate cost — BroadNet does not assert a price in this tool. [Protocol reference Read the spec behind this tool in the reference library.](https://www.broadnet.me/reference/gsm7-character-set) [SMS API REST + SMPP 3.4, Bearer-token auth, delivery webhooks.](https://www.broadnet.me/products/sms-api) [A2P SMS Application-to-person SMS at carrier scale.](https://www.broadnet.me/products/a2p-sms) [Developer hub Quickstart, TypeScript SDK, references and tools.](https://www.broadnet.me/developers) ## Ready to send at scale? BroadNet ships a Bearer-token REST API, direct SMPP 3.4 binds, delivery webhooks and an official TypeScript SDK. Talk to our team about routing and rates. [Developer hub](https://www.broadnet.me/developers) [Contact sales](https://www.broadnet.me/contact)