IPv6 Expander
Expand a shortened IPv6 address to full form, or compress a full one.
IPv6, expanded or compressed
IPv6 addresses are usually written in a shortened form, dropping leading zeros and collapsing runs of zero groups to ::. That is compact but ambiguous to read, so this tool converts between the shortened and fully expanded forms.
2001:db8::1 expands to 2001:0db8:0000:0000:0000:0000:0000:0001, and any full address compresses back to its shortest legal form. Seeing both is useful when a config or firewall rule needs the exact expanded value.
Standards-correct and private
It applies the RFC 5952 compression rules — collapsing only the longest zero run once — and runs entirely in your browser.
Frequently Asked Questions
What does expanding do?
It restores every group to four hex digits and replaces the :: shorthand with the zero groups it stands for, giving the unambiguous full form.
What are the compression rules?
Leading zeros in each group are dropped, and the longest run of all-zero groups is replaced once with ::. The tool applies both.
Does it validate the address?
It checks the structure — hex groups and a single :: — and reports if the input is not a valid IPv6 address.
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