Enter Networking Inputs
Example Data Table
| IPv4 Address | Prefix | Subnet Mask | Network Address | Broadcast Address | Usable Hosts |
|---|---|---|---|---|---|
| 192.168.10.34 | /26 | 255.255.255.192 | 192.168.10.0 | 192.168.10.63 | 62 |
| 10.20.40.99 | /20 | 255.255.240.0 | 10.20.32.0 | 10.20.47.255 | 4094 |
| 172.16.14.200 | /28 | 255.255.255.240 | 172.16.14.192 | 172.16.14.207 | 14 |
Formula Used
Host bits = 32 − prefix length.
Total addresses = 2host bits.
Usable hosts = 2host bits − 2 for standard subnets with more than two addresses.
Subnet mask is formed by placing prefix ones from the left, then host zeros.
Network address = IP address AND subnet mask.
Broadcast address = network address OR wildcard mask.
Wildcard mask = 255.255.255.255 − subnet mask.
Recommended prefix by hosts chooses the smallest prefix where usable hosts meet or exceed the required count.
How to Use This Calculator
- Enter a valid IPv4 address.
- Provide a prefix length, a subnet mask, or both.
- Optionally enter desired subnet count and host count.
- Press Calculate Prefix Details.
- Review the result panel above the form.
- Export the visible results using CSV or PDF buttons.
- Use binary outputs to verify mask boundaries and host bits.
Frequently Asked Questions
1. What does a subnet prefix represent?
A subnet prefix shows how many leading bits identify the network portion of an IPv4 address. The remaining bits are used for host addressing inside that subnet.
2. Why can I enter either a prefix or a mask?
Both values describe the same subnet boundary. A prefix such as /24 is shorthand for a subnet mask like 255.255.255.0.
3. How is the network address calculated?
The calculator applies a bitwise AND operation between the IPv4 address and the subnet mask. The result is the network address for that subnet.
4. Why are usable hosts sometimes fewer than total addresses?
Traditional IPv4 subnets reserve one address for the network and one for the broadcast. That leaves total addresses minus two as usable hosts in most cases.
5. What is the wildcard mask used for?
A wildcard mask is the inverse of the subnet mask. It is often used in access control lists, route filtering, and network matching rules.
6. What does the interesting octet increment mean?
It shows the subnet block jump in the mask octet where subnetting changes occur. This helps you quickly list subnet boundaries by inspection.
7. Can this calculator help size future networks?
Yes. Enter desired hosts or desired subnets to see recommended prefixes. This is useful for planning address allocation before deployment.
8. Does this tool support IPv6?
No. This version focuses on IPv4 subnet prefix analysis, masks, and host calculations. IPv6 requires different notation and planning rules.