Expand / Collapse IPv6 Addresses

Convert between expanded and compressed IPv6 address formats. Supports CIDR notation.

Due to their length, IPv6 addresses can be abbreviated by removing leading zeros and replacing consecutive groups of zeros with a double colon (::). This process is known as collapsing. Conversely, expanding an IPv6 address restores all leading zeros and omitted groups.

IPv6 Address

Expanded (Full Form)

Collapsed (Short Form)

How IPv6 Compression Works

Leading zeros in each group can be omitted: 2001:0db8 → 2001:db8
Consecutive zero groups can be replaced with :: (once per address)
Example: 2001:0db8:0000:0000:0000:0000:0000:0001 → 2001:db8::1

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