Every messaging platform has different limits. Here's a complete reference, plus the technical reasons for each limit.
| Platform | Limit per message | Note |
|---|---|---|
| SMS (GSM-7) | 160 characters | Basic Latin alphabet only |
| SMS (UCS-2) | 70 characters | If any non-Latin or emoji |
| SMS concatenated | 153 chars × 6 parts = 918 | Often charged as multiple SMS |
| MMS | Variable, ~1,600 chars text + media | Carrier-dependent |
| iMessage | No hard limit (practical ~50,000) | Falls back to SMS if recipient is non-iMessage |
| RCS | ~8,000 characters | Replacing SMS on modern Androids |
| ~65,536 characters | One of the most generous mainstream apps | |
| Telegram | 4,096 characters | Plus 1,024 for captions |
| Discord | 2,000 characters | 4,000 for Nitro subscribers |
| Slack | 40,000 characters | Per message |
| Microsoft Teams | ~28,000 characters | Estimated; not officially documented |
| X (Twitter) free | 280 characters | Per post |
| X Premium | 25,000 characters | Long-post feature |
| Instagram caption | 2,200 characters | Per post |
| Instagram comment | 2,200 characters | Per comment |
| Facebook post | 63,206 characters | Sometimes called "the Hamlet limit" |
| Facebook comment | 8,000 characters | Approximate |
| LinkedIn post | 3,000 characters | Per post |
| LinkedIn comment | 1,250 characters | Per comment |
| Reddit post | 40,000 characters | For self-posts |
| Reddit comment | 10,000 characters | Per comment |
| Email subject | ~78 characters recommended | RFC suggestion, not enforced |
| Email body | No hard limit (~10 MB) | Provider-dependent |
Friedhelm Hillebrand, a German engineer, set the 160-character limit in 1985 by typing random sentences on a typewriter and counting characters. He noticed most messages fit in 160 chars. The limit was then baked into the GSM standard. Forty years later, every SMS in the world still respects that limit.
SMS uses 7-bit encoding (GSM-7) for basic Latin characters — 1,120 bits ÷ 7 = 160 chars. For non-Latin alphabets (Cyrillic, Arabic, Chinese) or emojis, SMS switches to 16-bit UCS-2 encoding — 1,120 bits ÷ 16 = 70 chars. So one emoji can drop your effective SMS limit from 160 to 70.
When your message exceeds 160 chars (or 70 for UCS-2), the carrier splits it. Each part is technically a separate SMS and may be billed separately.
No fixed daily limit, but high-volume sending to non-contacts gets flagged. Business API accounts have explicit per-day limits.
Yes — every character counts, including spaces, newlines, and emojis. Complex emojis (with zero-width joiners) often count as multiple characters.
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A single SMS is limited to 160 characters using standard GSM encoding. Longer texts are split into segments (about 153 characters each once concatenation overhead is added) and reassembled by the recipient's phone. Using emoji or special characters switches the message to Unicode encoding, which drops the per-segment limit to about 70 characters.
Chat apps are far more generous than SMS. WhatsApp allows about 65,536 characters per message; Telegram 4,096; Discord 2,000 (4,000 with Nitro); Instagram captions 2,200 and bios 150; and X posts 280 (25,000 with Premium). The live counter in the repeater shows your output length so you can size it to the target.
Many emoji are two or more UTF-16 code units, and some are several combined, so a single emoji can count as 2+ toward a limit. That is why an emoji-heavy message hits a cap sooner than a plain one — watch the counter when you are close.