Subnet Calculator

Calculate IPv4 and IPv6 subnet details from CIDR notation. All calculations run instantly in your browser.

IP Address / CIDR IPv4

Supports IPv4 (e.g. 10.0.0.0/8) and IPv6 (e.g. 2001:db8::/32)

Network Information

Address Details

Host Counts

Properties

Hexadecimal

Binary

Subnet Splitting Options

New Prefix	Number of Subnets	Hosts per Subnet	Subnet Mask	Example

IPv4 Presets

IPv6 Presets

Understanding CIDR Notation

IPv4 CIDR

IPv4 uses 32-bit addresses with CIDR prefixes from /0 to /32. A /24 has 256 addresses (254 usable). Common: /24 (254 hosts), /16 (65K hosts), /8 (16M+ hosts).

IPv6 CIDR

IPv6 uses 128-bit addresses with CIDR prefixes from /0 to /128. A /64 is the standard subnet with 2^64 addresses. IPv6 does not use broadcast.

Special Ranges

Private IPv4: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16. IPv6 ULA: fc00::/7. Link-local: 169.254.0.0/16 and fe80::/10. Loopback: 127.0.0.0/8 and ::1/128.