Subnet Calculator
Turn any CIDR into its ranges
Network Address
192.168.1.0
Broadcast Address
192.168.1.255
Subnet Mask
255.255.255.0
Wildcard Mask
0.0.0.255
First Usable Host
192.168.1.1
Last Usable Host
192.168.1.254
CIDR Notation
192.168.1.0/24
CIDR Prefix
/24
IP Class
C
Total Hosts
256
Usable Hosts
254
Usable host count excludes the network and broadcast addresses. /31 and /32 blocks are special cases (point-to-point and single-host).
What Is the Subnet Calculator?
The Subnet Calculator turns any IPv4 CIDR block into its full set of network details — network address, broadcast address, subnet mask, wildcard mask, and the usable host range — instantly in your browser. Enter a CIDR like 192.168.1.0/24 and get every value a network engineer needs, with no installs and no data leaving the page.
Key Features
Understanding CIDR and Subnets
CIDR notation (like /24) describes how many bits of an IP address identify the network versus individual hosts. From that single number, you can derive the subnet mask, the address range, and how many devices fit in the block. The calculator does this math for you, eliminating the manual binary conversions that are easy to get wrong.
When to Use a Subnet Calculator
Network administrators use subnet calculations to plan IP allocation, configure firewalls and routers, and define access-control rules. Proxy and scraping users often need to know the range a CIDR block covers when allow-listing IPs or interpreting an ASN. The calculator gives instant, error-free answers for any of these tasks.
Common Use Cases
- Planning IP address allocation for a network
- Converting a CIDR block into its usable host range
- Configuring firewall and access-control rules
- Interpreting the size of an IP range or ASN block
Frequently Asked Questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation writes an IP range as an address followed by a slash and a number, like 10.0.0.0/8. The number is how many leading bits identify the network, which determines the size of the block.
What is the difference between network and broadcast address?
The network address is the first address in a subnet and identifies the network itself, while the broadcast address is the last address and is used to send data to all hosts on the subnet. Neither can be assigned to a device.
Why are usable hosts fewer than total hosts?
Every subnet reserves two addresses — the network address and the broadcast address — that cannot be assigned to devices. So a /24 has 256 total addresses but 254 usable hosts.
Does this support IPv6?
This calculator focuses on IPv4 CIDR blocks, which cover the vast majority of subnetting tasks. IPv6 uses the same prefix concept but a far larger address space.
Is the subnet calculator free?
Yes, it is completely free and runs entirely in your browser with no sign-up, so you can run as many calculations as you need.
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