Online Subnet Calculator | IPv4 & IPv6 | VLSM

IPv4 ClassesA·B·C·DClassful legacy

CIDR Range/1–/32IPv4 prefix lengths

IPv6 CIDR/1–/128128-bit address space

ExportCSV·JSONBulk subnet export

Input Parameters

IPv4 Address

CIDR Prefix Length

Quick Reference

CIDR	Hosts	Mask
/24	254	255.255.255.0
/25	126	255.255.255.128
/26	62	255.255.255.192
/27	30	255.255.255.224
/28	14	255.255.255.240
/30	2	255.255.255.252

About Subnet Calculator Pro

Professional-grade network calculator. IPv4 CIDR analysis with address type detection. IPv6 sequential planning and /48/56 split strategies. VLSM automatic allocation. Supernetting / CIDR aggregation. All results exportable as CSV or JSON.

Capabilities

IPv4 CIDR — network, broadcast, wildcard, RFC range detection
IPv6 Planner — sequential prefix generation, expandable preview, CSV/JSON export
IPv6 Split — /48 or /56 to /64 with full export
VLSM — automatic allocation from a base block sorted by size, utilisation bar
Supernet — CIDR aggregation to smallest enclosing prefix