IPv6 CIDR to Range

The IPv6 CIDR to Range tool provides the start and end IPv6 address for an IPv6 address range using CIDR notation.

Enter an IPv6 address width CIDR (for example 2001:DB8::/48).

IPv6 CIDR - Classless Inter Domain Routing

With CIDR a single IPv6 address can be used to allocate many unique IPv6 addresses.
A CIDR IPv6 address looks like a IPv6 address except that it ends with a slash character and a decimal number of leading bits of the routing prefix. For example: 2001:db8::/48.

The number 48 indicates that the first 48 bits are used for network ID and the remaining 80 are used for host ID (An IPv6 address size is 128bits).

Why CIDR excist
CIDR is a solution for large routing tables.
CIDR allows a more efficient and appropriate way to allocate many addresses.