Subnet Calculator (CIDR Calculator)
Calculate network ranges, subnet masks, and usable hosts from an IP and CIDR instantly.
Calculation Results
Common CIDR Reference
| CIDR | Mask | Hosts |
|---|---|---|
| /8 | 255.0.0.0 | 16,777,214 |
| /16 | 255.255.0.0 | 65,534 |
| /24 | 255.255.255.0 | 254 |
| /25 | 255.255.255.128 | 126 |
| /26 | 255.255.255.192 | 62 |
| /27 | 255.255.255.224 | 30 |
| /28 | 255.255.255.240 | 14 |
| /29 | 255.255.255.248 | 6 |
| /30 | 255.255.255.252 | 2 |
| /31 | 255.255.255.254 | 2 |
| /32 | 255.255.255.255 | 1 |
Subnet Calculator Use Cases
Frequently Asked Questions
Q. What does /24 mean?
It means the first 24 bits are the network portion, leaving 8 bits for hosts—providing 256 total addresses, with 254 usable.
Q. Why are there 2 fewer usable hosts?
The first address is the network ID and the last is the broadcast address; both are reserved and cannot be assigned to devices.
Q. What is the /31 exception?
RFC 3021 allows using /31 for point-to-point links where no broadcast is needed, giving 2 usable addresses.
Q. Difference between subnet mask and wildcard?
Subnet mask uses 1s for network bits (255.255.255.0). Wildcard is the inverse (0.0.0.255), mainly used in firewall ACLs.
Q. Can I subnet a /24 into smaller networks?
Yes. You can split a /24 into two /25s (128 each), four /26s (64 each), eight /27s (32 each), and so on.
Key Features
- Real-time CIDR Mask Calculation
- Binary Mask Visualization
- IP Class & Private IP Detection
- RFC 3021 /31 Support & Host Counting
Subnet Mask Calculator
Precision network calculator and IP range tool. Free CIDR to subnet mask converter and subnetting designer.
CIDR Logic
Analyze subnetting details and wildcard masks for advanced network planning.
Network bits (0–32)
Common CIDR Use Cases
| CIDR | Subnet Mask | Hosts | Typical Use |
|---|---|---|---|
| /8 | 255.0.0.0 | 16,777,214 | Large ISP / Class A |
| /16 | 255.255.0.0 | 65,534 | University / Enterprise campus |
| /24 | 255.255.255.0 | 254 | Home / Small office |
| /25 | 255.255.255.128 | 126 | Small department VLAN |
| /26 | 255.255.255.192 | 62 | Workgroup / Lab |
| /28 | 255.255.255.240 | 14 | DMZ / server cluster |
| /29 | 255.255.255.248 | 6 | Cloud VPC subnet |
| /30 | 255.255.255.252 | 2 | Point-to-point WAN link |
| /31 | 255.255.255.254 | 0* | Router inter-link (RFC 3021) |
| /32 | 255.255.255.255 | 1 | Single host / loopback |
* /31 = 2 addresses, host-usable per RFC 3021