IP Subnet Calculator
Calculate network address, broadcast IP, host range, and subnet mask from any CIDR notation.
How to use
- 1 Enter an IP address in CIDR notation (e.g. 192.168.1.0/24) into the input field.
- 2 Click Calculate — the tool computes the network address, broadcast address, subnet mask, and usable host range.
- 3 Check the number of usable host addresses for your subnet prefix.
- 4 Use the results to plan your network topology or configure firewall rules.
Key features
- Calculates network address, broadcast, subnet mask, and usable host range
- Supports all CIDR prefixes from /0 to /32
- Shows the number of usable host addresses
- Useful for network planning, firewall rules, and cloud VPC configuration
What is CIDR Notation?
CIDR (Classless Inter-Domain Routing) is the compact way to describe an IP network. 192.168.0.0/24 means "192.168.0.x — all 256 addresses where the first 24 bits are fixed." The number after the slash is the prefix length: the higher it is, the smaller the network.
CIDR replaced the old Class A/B/C system in 1993 (RFC 1519), enabling more efficient use of the IPv4 address space. Every cloud platform — AWS VPCs, GCP subnets, Azure VNets — uses CIDR notation to define network boundaries.
Common Use Cases
Cloud VPC and subnet design
Calculate available host ranges before creating subnets in AWS, GCP, or Azure to avoid overlap.
Firewall rules and allowlists
Verify that a CIDR block covers the right range of IPs before adding it to a security group or firewall.
Office network planning
Determine how many usable host addresses fit in a planned subnet before allocating address space.
VPN split tunneling config
Calculate the exact network address and mask needed for routing table entries in a VPN client.
Networking study and practice
Check your manual subnetting calculations against this tool while studying for CCNA or CompTIA Network+.
Zero Trust access policies
Verify that IP-based access conditions in IAM policies reference the correct CIDR blocks.
Common Subnet Sizes
The prefix lengths you'll encounter most in cloud and on-premises networking.
| CIDR | Usable hosts | Typical use |
|---|---|---|
| /32 | 1 | Single host firewall rule |
| /30 | 2 | Point-to-point link |
| /28 | 14 | Small cloud subnet |
| /24 | 254 | Standard LAN, office network |
| /16 | 65,534 | AWS/GCP VPC default (10.0.0.0/16) |
| /8 | 16,777,214 | Large private network (10.x.x.x) |