IP/CIDR Calculator
NetworkCalculate subnet info, host ranges, and split subnets from CIDR notation
Enter a block like `10.0.0.0/24` and get the network address, broadcast address, and usable host range immediately, or go the other way and enter a required host count to find the smallest subnet mask that fits it. It also splits a larger subnet into smaller ones, which comes up constantly when planning VPC subnets across multiple availability zones, and checks whether a given IP falls inside a CIDR range before you write a firewall or security group rule around it. Both IPv4 and IPv6 CIDR notation are supported, though host-range math is most commonly used with IPv4 in practice. The usable host count is typically the block total minus 2, since the network and broadcast addresses are reserved, except for /31 and /32 blocks, which follow special rules of their own. All subnet math runs locally.
How to use IP/CIDR Calculator
- 1.Enter a CIDR block like `10.0.0.0/24` to get the network address, broadcast address, and usable host range instantly.
- 2.Split a larger subnet into smaller ones when planning VPC subnets across multiple availability zones.
- 3.Check whether a specific IP falls inside a given CIDR range before writing a firewall or security group rule.
Frequently asked questions
Use via API, SDK, or MCP
cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/ip-subnet \
-H "Authorization: Bearer utx_live_..." \
-H "Content-Type: application/json" \
-d '{"cidr": "192.168.1.0/24"}'Get an API key from your dashboard · Full API docs →