Calculator Form
Use any IPv4 with a CIDR prefix. The tool checks whether the address belongs to a private range and calculates core subnet details.
Example Data Table
| IPv4 Address | CIDR | Network | Usable Range | Usable Hosts | Private Pool |
|---|---|---|---|---|---|
| 192.168.10.25 | /24 | 192.168.10.0 | 192.168.10.1 — 192.168.10.254 | 254 | 192.168.0.0/16 |
| 10.12.5.99 | /20 | 10.12.0.0 | 10.12.0.1 — 10.12.15.254 | 4,094 | 10.0.0.0/8 |
| 172.20.14.8 | /28 | 172.20.14.0 | 172.20.14.1 — 172.20.14.14 | 14 | 172.16.0.0/12 |
| 192.168.100.200 | /26 | 192.168.100.192 | 192.168.100.193 — 192.168.100.254 | 62 | 192.168.0.0/16 |
| 10.0.0.1 | /30 | 10.0.0.0 | 10.0.0.1 — 10.0.0.2 | 2 | 10.0.0.0/8 |
Formula Used
Network Address = IP Address AND Subnet Mask
Broadcast Address = Network Address OR Wildcard Mask
Wildcard Mask = 255.255.255.255 minus Subnet Mask
Total Addresses = 2(32 − Prefix)
Usable Hosts = 2(32 − Prefix) − 2 for most subnets
Special Cases: /31 gives two usable endpoints, while /32 represents one host route.
Recommended Prefix is the largest prefix that still supports your required host count.
How to Use This Calculator
- Enter an IPv4 address that you want to analyze.
- Type the CIDR prefix length, such as /24 or /28.
- Select a planning pool or let the tool detect one automatically.
- Enter expected hosts per subnet for sizing guidance.
- Enter how many subnets you want to create.
- Press Calculate Private IP to show the result above the form.
- Review the network, broadcast, mask, host range, and private pool details.
- Use the CSV or PDF buttons to save the current output.
Frequently Asked Questions
1) What is a private IP address?
A private IP address is used inside internal networks and is not routed across the public internet. Common ranges come from RFC 1918.
2) Which IPv4 ranges are private?
The three private IPv4 blocks are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These are reserved for local addressing.
3) Why does the tool show a network and broadcast address?
Those values define the subnet boundary. The network address identifies the subnet, while the broadcast address reaches every device inside that subnet.
4) Why are usable hosts usually two fewer than total addresses?
Most IPv4 subnets reserve one address for the network and one for broadcast. That leaves the remaining addresses for hosts.
5) What is the difference between CIDR and subnet mask?
CIDR is the slash notation, such as /24. The subnet mask is the dotted decimal version, such as 255.255.255.0. Both describe the same boundary.
6) When should I use a /31 or /32?
Use /31 mainly for point-to-point links. Use /32 for a single host route, loopback, or exact host identification in routing and firewall rules.
7) Can this calculator analyze a public IPv4 address too?
Yes. It still performs subnet calculations for any valid IPv4 address, then tells you whether the address belongs to a private range.
8) Why do I need a recommended prefix?
A recommended prefix helps you size subnets efficiently. It shows the smallest subnet that still fits your required host count.