String Length Calculator
String length online calculator: count characters, UTF-8 bytes, UTF-16 code units free. No upload, no account. Paste text to check byte length for APIs and databases.
Runs locally in your browser. Your input is not uploaded to DevToolMate servers.
Character vs byte length
Emoji and non-ASCII characters can use more than one UTF-8 byte.
Developer Quick Tips
- Calculate string length in bytes online before API calls. UTF-8 byte length is what REST APIs enforce, not character count. Emoji use multiple bytes.
- Check string length for emoji: one emoji is 1 character but 4 UTF-8 bytes. Verify byte length for API payload and database column limits.
- Paste text to count string length instantly. See character count, UTF-16 code units, and UTF-8 bytes live without leaving your browser.
- Use byte length to verify VARCHAR limits, JSON payload size, and storage constraints. Character count alone misses emoji-heavy content overages.
Frequently asked questions
How do I check string length online?
Paste or type text into the String Length Calculator. It instantly shows character count, UTF-16 code units, and UTF-8 byte length. All processing happens in your browser with no upload.
What is the difference between character count and byte length?
Character count is the number of visible characters. Byte length is the UTF-8 encoded size. Emoji and non-ASCII characters use multiple UTF-8 bytes each. For example, a single emoji is 1 character but 4 UTF-8 bytes. APIs and databases enforce byte limits, not character limits.
How do I calculate string length in bytes online?
Paste your text into the calculator and check the UTF-8 byte count. Most REST APIs enforce byte limits on request bodies and headers. A 100-character string with emoji may exceed a 200-byte limit, so always verify byte length before sending.
How many bytes is a string with emoji?
Emoji and accented characters encode to multiple UTF-8 bytes. A single emoji is 1 character but 4 UTF-8 bytes. UTF-16 code units may also differ. Paste your text into the calculator to see exact byte length for your content.
What is UTF-16 code unit length vs UTF-8 byte length?
UTF-16 code units (JavaScript string.length) count 16-bit units. UTF-8 bytes are the actual storage size. Most emoji use 1 UTF-16 code unit but 4 UTF-8 bytes. For APIs and databases, always use UTF-8 byte length.
When should I use byte length vs character count?
Use character count for display and user-facing text limits. Use byte length for API payloads, database VARCHAR columns, and storage constraints. Most backend systems enforce byte limits, not character limits.
Does String Length Calculator upload my data?
No. String Length Calculator runs entirely in your browser. Your input is never uploaded to DevToolMate servers or any external service.
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