Network address, broadcast address, first/last host, total host count, wildcard mask, and subnet mask. Everything you need to design or audit a network.

Both. IPv6 CIDR ranges have enormous host counts — displayed in scientific notation so you know what you're dealing with.

Why does /0 give 4 billion hosts?

It matches everything. /8 gives 16M, /16 gives 65k, /24 gives 256, /32 is one host. Smaller number = larger range.

Does it check if my subnet fits my provider's rules?

No — providers impose their own CIDR constraints (AWS VPC needs /28 to /16). The tool does math; the rules are provider-specific.

CIDR Calculator | DevTools Surf

DevTools Surf

Example: CIDR Calculator

A worked example, rendered from real sample data. Sign in to run the tool on your own input.

Input

192.168.1.0/24

Output

═══ 192.168.1.0/24 ═══
Network: 192.168.1.0
Netmask: 255.255.255.0 (/24)
Wildcard: 0.0.0.255
Broadcast: 192.168.1.255
First host: 192.168.1.1
Last host: 192.168.1.254
Total addresses: 256
Usable hosts: 254
Host bits: 8
Scope: Private

─── Binary ───
Netmask: 11111111.11111111.11111111.00000000
Network: 11000000.10101000.00000001.00000000

About CIDR Calculator

CIDR Calculator preview - Networking tool

Calculate network address, broadcast, host range from CIDR notation. Part of the DevTools Surf developer suite. Browse more tools in the Networking collection.

Use Cases

Plan VPC subnets for AWS or GCP cloud deployments
Calculate usable host ranges for network documentation
Verify firewall rules reference the correct IP ranges
Design IP allocation schemes for multi-tenant environments

Tips

Enter a CIDR block to see the full host range instantly
Compare subnet sizes by adjusting the prefix length
View the broadcast and network addresses for any subnet

Fun Facts

CIDR (Classless Inter-Domain Routing) was introduced in 1993 via RFC 1519 to slow the exhaustion of IPv4 addresses by replacing classful networking.
A /32 subnet contains exactly one IP address, while a /0 represents the entire IPv4 address space of 4,294,967,296 addresses.
The last unallocated IPv4 /8 blocks were distributed by IANA on February 3, 2011, marking the official exhaustion of the IPv4 free pool.

FAQ

What does it show?: Network address, broadcast address, first/last host, total host count, wildcard mask, and subnet mask. Everything you need to design or audit a network.
IPv4 and IPv6?: Both. IPv6 CIDR ranges have enormous host counts — displayed in scientific notation so you know what you're dealing with.
Why does /0 give 4 billion hosts?: It matches everything. /8 gives 16M, /16 gives 65k, /24 gives 256, /32 is one host. Smaller number = larger range.
Does it check if my subnet fits my provider's rules?: No — providers impose their own CIDR constraints (AWS VPC needs /28 to /16). The tool does math; the rules are provider-specific.

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