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mac · ethernet · format · live

Normalise MAC addresses across separators

Paste a MAC address in any separator style and get all the common forms back: colon, dash, dot, Cisco quad, no-separator, upper and lower case. Runs entirely in your browser.

MAC Address Formatter
Input
17 B
mac
Hex digits
12
of 12
Forms
5
output
Status
ok
live
Any separator accepted — colon, dash, dot, none
input · mac
output · formats
lower:colon00:11:22:33:44:55
lower-dash00-11-22-33-44-55
UPPER:COLON00:11:22:33:44:55
nosep001122334455
cisco.style0011.2233.4455
Quick Start

How to format a MAC address

A MAC address is 48 bits — twelve hex digits. Vendors and operating systems write them with different separators; the bits are always the same.

  1. 01

    Paste any form

    Colon, dash, dot, or even no separator — all accepted.

    Bytes flow through TextEncoder/TextDecoder for predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.

    inputUTF-8TextEncoderlosslesslive
    input · raw bytesmac · UTF-8
    001122334455
    loaded · UTF-8MIME · ready
  2. 02

    Normalised

    Non-hex characters are stripped before parsing.

    Hash and signature operations call crypto.subtle from the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.

    cleanWeb Cryptosubtledeterministiclive
    hex · options12 digits · live
    001122334455
    options applied · livelive
  3. 03

    Re-emit forms

    Colon, dash, Cisco quad — pick whichever your tool expects.

    Options re-run instantly through useEffect + useMemo — switching URL-safe mode or padding doesn’t re-encode from scratch.

    formsmemoisedoptionsinstantreactive
    out · encodedforms · ready
    00:11:22:33:44:55
0011.2233.4455
    encoded · livelossless
  4. 04

    Copy the one you need

    Per-row copy buttons grab just one format.

    Copy uses the Async Clipboard API; downloads ship via Blob with the appropriate MIME (text/plain, image/png, …) so external tools recognise them.

    exportclipboardblobMIME-correctclient-side
    ok · copiedready · done
    Copied
    shipped · ready to shipsuccess
Pro tips

Encoding without surprises

Always UTF-8 first

Use TextEncoder / TextDecoder for bytes ↔ string conversion. btoa alone breaks on non-ASCII.

URL-safe vs standard Base64

Standard uses +, /, =; URL-safe swaps to -, _, no padding. Don’t mix them.

Hashes aren’t passwords

SHA-256 is fast; that’s good for fingerprints, bad for passwords. Use bcrypt / argon2 for credentials.

Watch padding rules

Some decoders are strict about = padding, others auto-pad. If round-trips fail at exactly 1 or 2 bytes, check padding.

Use Web Crypto for keys

Generate cryptographic keys via crypto.subtle, never Math.random. The latter is predictable.

JWT decode ≠ verify

Decoding a JWT just splits and base64-decodes. Verification needs the issuer’s public key / shared secret.

Related toolsIP to IntegerCIDR CalculatorIPv6 ConverterHex to DecimalText to HexUUID
Use Cases

When to reformat MACs

Switching gear, log parsing, scripts, DHCP reservations.

Vendor mismatch

Cisco wants 0011.2233.4455; Linux wants 00:11:22:33:44:55. Output round-trips losslessly with the matching decoder — both run client-side, so end-to-end testing happens in a single tab. Encoding flows through TextEncoder for predictable UTF-8 semantics.

RFC-compliant

DHCP reservations

Paste from one form, copy into another. Web Crypto's subtle.digest produces output that matches OpenSSL, GPG, and Node's crypto module byte-for-byte. That makes the result trustworthy as a content fingerprint, ETag, or integrity check.

OpenSSL-matched

Log parsing

Normalise MACs from mixed sources before joining. Pairs cleanly with HMAC, JWT, and signed-URL workflows where bit-level correctness matters. The browser's crypto stack is FIPS 140-validated in Chrome and Firefox, so it's production-grade.

lossless

Scripting

Get the nosep form for compact storage or hashes. Output uses canonical RFC 4648 / 7515 alphabets so curl, openssl, and any standards-compliant decoder accept it as input. URL-safe variants drop padding for tokens that travel in query strings.

byte-identical

Case rules

Some systems require uppercase — flip with one click. Heavy hashing runs through useMemo so large inputs don't block typing. PBKDF2, bcrypt, and Argon2 expose configurable cost factors — tune for your threat model, not the default.

spec-grade

Network audits

Standardise documentation across switches and routers. Same input plus same options always yields identical bytes. That's the foundation for content-addressed storage (IPFS, Git, S3 ETags) and means the output is safe to commit to fixtures.

production-ready
FAQ

Frequently asked questions

Any non-hex character is stripped. Colon, dash, dot, space, or no separator all work as input.
Cisco IOS groups four hex digits between dots — historically easier to read at a glance on a console.
Not for the address itself — but many systems require either upper or lower case. The tool emits both.
No — it only checks length and hex validity. The OUI portion (first 6 digits) isn't looked up against IEEE.
No. Formatting runs locally in your browser.
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