CIDR / Subnet Calculator
Calculate the network address, broadcast, subnet mask, wildcard mask, usable host range, and capacity for any IPv4 CIDR block. Includes binary representation and IP class detection. Runs in your browser.
About CIDR & Subnets
Calculates network, broadcast, mask, host range, and capacity for any IPv4 CIDR block. For decoding HTTP request headers see theUser-Agent Parser.
Secure & Private Client-Side
This tool runs entirely in your browser. No data is sent to any server, ensuring your information remains private and secure.
About CIDR / Subnet Calculator
Calculate the network address, broadcast, subnet mask, wildcard mask, usable host range, and capacity for any IPv4 CIDR block. Includes binary representation and IP class detection. Runs in your browser.
Frequently Asked Questions
What does CIDR notation mean? expand_more
CIDR notation like 192.168.1.0/24 means the first 24 bits are the network prefix. The remaining 8 bits identify hosts, giving 256 addresses in this example.
How are usable hosts calculated? expand_more
For prefixes of /30 or smaller, the network address and broadcast address are reserved, so usable hosts equal total addresses minus 2. /31 and /32 are special point-to-point and single-host cases.
What is the wildcard mask? expand_more
The wildcard mask is the bitwise inverse of the subnet mask. It is used in access control lists and OSPF configuration to match a range of IPs.
Need to look up a single IP? expand_more
Use the [IP Address Info](/tools/ip-info/) tool to inspect class, range, and reverse DNS for a specific address.
Is my input uploaded? expand_more
No. Everything runs locally in your browser.
Common Use Cases
- Network Setup: Plan subnets for office or cloud VPCs.
- Firewall Rules: Compute the host range a rule will cover.
- IP Allocation: Confirm how many addresses a block can serve.
- Education: Visualize how the prefix length changes the mask.