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Keep the complete address
Paste one six-byte value. Outer whitespace is ignored, but short bytes, internal spaces and mixed separators are rejected instead of silently repaired.
IP & Network
MAC address formatter
Check one 48-bit address, compare four notations, or preview a locally administered test value.
MAC address formatter
MAC address input
Address formats and flags
- Colon
- 02:1A:2B:3C:4D:5E
- Hyphen
- 02-1A-2B-3C-4D-5E
- Cisco dotted
- 021A.2B3C.4D5E
- No separator
- 021A2B3C4D5E
- Bytes: hex (decimal)
- 02 (2) · 1A (26) · 2B (43) · 3C (60) · 4D (77) · 5E (94)
- First byte, most significant bit first
- 00000010
- I/G — bit 0
- 0 · Unicast
- U/L — bit 1
- 1 · Locally administered bit set
Addresses are processed in this browser; no device or vendor is queried.
Conversion options
Read the rightmost bit for I/G and the next bit for U/L. These flags do not verify assignment or a manufacturer.
Generation fixes local and unicast bits only. Test values may collide and do not claim a hardware vendor.
Address parsed; formats and flags are current.
When a switch export uses dots but a configuration form expects colons, use the MAC address formatter to preserve the address while changing its notation. The six byte values stay visible, so a separator change cannot hide a missing digit. The same result also explains the two flags that are often confused with a vendor identity.
Why use this MAC address formatter?
Inspect the value behind the punctuation before putting it into a configuration.
One value, four notations
The MAC address formatter shows colon, hyphen, Cisco dotted and unseparated forms together. Leading zeroes remain in place and byte order never changes. This makes a switch record and a DHCP reservation directly comparable without editing the source text.
Two flags, visible in context
A locally administered MAC is identified by the second bit from the right in the first byte. A generated test value sets that bit and clears the rightmost group bit. Preview the replacement before applying it; undo restores both the previous input and its result.
Check the grouping before you export
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Use the export settings deliberately
All four forms are shown at once. Choose which one to copy or download, then select letter case. Changing either setting locks the old export until the next conversion. Disable automatic mode to run with Ctrl/Cmd + Enter.
03
Review a generated replacement
Generate test value opens a preview, including how many input lines it replaces. Apply it to inspect the new address, or cancel to keep the original. Undo restores one previous input and result together.
Notation, bytes and test values
Strict conversion
Use the MAC address converter with six colon-separated or hyphen-separated bytes, three Cisco dotted MAC groups, or twelve contiguous hex digits. Uppercase and lowercase input are equivalent; zero padding is preserved.
Bit-level inspection
The MAC address validator shows each byte in hexadecimal and decimal, plus the first byte in binary. I/G=0 is unicast; I/G=1 is a group address. U/L=1 marks local administration. All-zero and broadcast values receive a separate notice.
Controlled random input
Six random bytes come from Web Crypto when you explicitly request a test value. The local bit is set and the group bit is cleared. The remaining bits are kept random; generation never borrows a manufacturer prefix from a vendor database.
What validation can and cannot establish
- Exactly 48 bits
- EUI-64, IPv6 derivation and reversed bit order are outside this tool. A sixteen-digit value is rejected rather than truncated to twelve digits. Formatting changes punctuation and case only.
- No silent repair
- Each colon or hyphen group must contain two hex digits; each dotted group must contain four. Mixed separators, non-ASCII hex, prefixes such as 0x and internal spaces fail validation. Only outer whitespace is trimmed.
- One address per operation
- Lists, log extraction and file import are not supported. Multiple lines, commas and semicolons are errors. Input is limited to 256 UTF-16 code units, including outer whitespace; exceeding the limit blocks export.
- No vendor or device proof
- There is no OUI lookup, MAC-to-IP lookup, network scan or network-adapter change. A clear U/L bit describes the field but does not prove that the address was assigned to a real manufacturer device.
- Random does not mean unique
- Generated values are local unicast test data, not globally assigned identifiers. They can collide with existing addresses. The generator does not implement an allocation service or the optional structured local address plan.
- Special values remain inspectable
- FF:FF:FF:FF:FF:FF and 00:00:00:00:00:00 can be formatted, with a notice. Syntax success is not permission to use either as an ordinary host address; reachability and network policy are not checked.
MAC address formatter FAQ
Which MAC address notations can I convert?
Colon, hyphen, Cisco dotted and twelve-digit bare hexadecimal are accepted. They all describe the same six bytes. Do not mix separator styles within one value, and retain leading zeroes.
How do I recognize a locally administered MAC?
Inspect U/L, the second-least-significant bit of the first byte. A value of 1 marks local administration. The sample starts with 02, whose two low bits are 10: local and unicast.
How is multicast detected?
I/G is the least-significant bit of the first byte. A 1 identifies a group address. The all-FF broadcast value is a special case, so the result labels it separately rather than calling it an individual device.
Does the tool identify the hardware vendor?
No. The displayed bytes and flags come entirely from the entered value. There is no OUI database lookup, and a universally administered bit pattern is not evidence that a particular device exists.
Does it work with 64-bit EUI-64 addresses?
No. This page is limited to 48-bit addresses. Eight-byte EUI-64 values are rejected, and the tool does not insert FF:FE, flip a bit for IPv6 or derive an interface identifier.
Found an address representation we should examine?
Compare the next address
Use the MAC address formatter to check the byte count and flags, then copy the notation your configuration expects.