SMS Character Counter & Segment Calculator
See how your message is encoded, where its segments end and what it may cost. Your text stays in your browser.
Your SMS draft
User-perceived characters: 0
Advanced settings
The alternate profile reserves a larger header. Twilio documents these smaller capacities for multipart toll-free SMS to the US and Canada; they are not universal.
Live estimate
0
segments
GSM-7
0 septets
160 of 160 septets available in the current segment
Common · 153 / 67
Estimate for the selected model. Your provider may handle the message differently.Your draft and cost inputs stay in this browser tab. Nothing is uploaded or saved.
Segment preview
Boundaries preserve the original text, including line endings. Send the complete original through your provider; do not send these previews separately.
Add a message to see its segments.
Review substitutions
Select each change to preview it. Punctuation replacements may alter typography or meaning. The original draft is never changed.
No curated substitutions are available. Languages, names and emoji are not transliterated.
Estimate campaign cost
Enter your own price to calculate an estimate.
Segments × recipients × price per segment. Round only the final total to the currency’s decimal places.
No exchange conversion, taxes or surcharges are included. Retries, failed delivery, destination, sender type, carrier and contract terms can change the bill.
SMS encoding capacities
| Encoding | Single part | Multipart, per part |
|---|---|---|
| GSM-7 septets | 160 | 153 |
| Unicode UTF-16 units | 70 | 67 |
In the common profile, 160 GSM septets fit one SMS; 161 require concatenation. Every part then reserves a UDH, leaving 153 septets or 67 UTF-16 units. GSM extension characters use two septets. CR and LF each consume one unit; CRLF consumes two. Line endings are never normalized.
Providers commonly call Unicode SMS UCS-2. Here it is modeled with UTF-16 units: 🙂 uses two, while a joined emoji may use many. The supporting character count measures graphemes, not transport units.
How to check an SMS
- Paste your message. Auto chooses GSM-7 when every symbol fits its alphabet; otherwise it uses Unicode.
- Read the segment estimate and inspect the characters that affect encoding. Open Advanced settings only if your gateway uses a different profile.
- Review the exact segment previews. Optionally select punctuation substitutions or enter your own price and recipient count.
Features
- Shows GSM-7 or Unicode encoding and segment estimates
- Highlights characters that change encoding
- Previews segments and optional cost estimates
- Shows room left in the current segment
- Offers alternative concatenation profiles in advanced settings
- Suggests punctuation substitutions without changing your draft automatically
Use cases
- Find out why a short SMS became two segments
- Estimate a campaign using your own price
- See how emoji or smart quotes affect SMS length
- Compare wording to reduce the estimated segment count
Understanding SMS length
GSM-7 is a specific alphabet, not ASCII. It includes é and ñ but not every accented letter. Braces, brackets, the euro sign and several other extension characters need an escape and therefore use extra space.
Привет, 你好 and مرحبا naturally require Unicode in this model. This is normal language support, not a writing error. Even one smart quote in an otherwise GSM-compatible message changes the encoding of the entire draft.
A code point identifies a Unicode symbol; UTF-16 may represent it with one or two code units. A grapheme is a perceived character that can combine multiple code points. For example, e plus a combining acute accent and a family emoji each look like one character but occupy several units.
Long SMS messages use a User Data Header (UDH) to identify and reassemble parts. Header space reduces the payload of every part. Preview boundaries preserve combined characters and may leave space that a gateway would use differently.
Privacy and model limitations
Drafts, prices and recipient counts are held only in memory in this tab. Reloading clears them. Copying happens only when you choose a copy action. This tool neither sends SMS nor asks for a phone number.
National-language locking and single-shift tables, binary payloads, application ports, appended opt-out text, sender signatures, transliteration and carrier policies are outside this model. A provider may normalize, replace, append, reject or segment content differently. MMS and RCS are not calculated.
Use the price from your provider’s agreement for the destination and sender type. Currency selection changes display only. The final estimate is not a quote or a guarantee of the bill.
SMS counter questions
Sources and verification
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