IP subnet calculator

2001:bc8:1400::-2001:bc8:1bff:ffff:ffff:ffff:ffff:ffff

2001:bc8:1400::-2001:bc8:17ff:ffff:ffff:ffff:ffff:ffff
2001:bc8:1400::/38

2001:bc8:1800::-2001:bc8:1bff:ffff:ffff:ffff:ffff:ffff
2001:bc8:1800::/38