IPv4 Subnet Calculator is designed for the exact search intent behind “ipv4 subnet calculator”. Calculate IPv4 network details from an address and CIDR prefix, including mask, network, broadcast and usable range where applicable. Calculate IPv4 network details from an address and CIDR prefix, including mask, network, broadcast and usable range where applicable. CIDR prefix An IPv4 prefix /n fixes n network bits out of 32. Total addresses = 2^(32−n) . Network and broadcast The network address has all host bits zero; the traditional broadcast address has all host bits one. Usable hosts The old total−2 shortcut has exceptions such as /31 point-to-point networks and /32 single-host routes, so implementations should label semantics carefully. Worked example: A /24 contains 2^8 = 256 total IPv4 addresses. Common practical uses include Plan subnets; Check CIDR blocks; Verify masks; Calculate address ranges. Important limitations: Usable-host rules have /31 and /32 exceptions. This does not check route ownership. Overlapping subnet planning needs additional comparison logic. Key questions this page should answer include: How many addresses are in a /24? 256 total addresses. What is a subnet mask for? It separates network bits from host bits. Is usable hosts always total minus two? No. What does /32 mean? A single IPv4 address prefix. Does this tell me who owns the IP range? No. The page should stay focused on this differentiator: CIDR prefix. The tool should appear before the explanatory copy so a visitor can complete the task immediately, then use the supporting content to verify the method and understand the result. The explanation should keep terminology consistent with the calculator or converter interface, because a mismatch between labels in the tool and labels in the content can create confusion and weaken search-intent alignment. Where the calculation or transformation has edge cases, the page should state them directly instead of implying that every input is valid. The worked example should mirror the real inputs accepted by the tool and show enough arithmetic or transformation logic for the result to be independently checked.
How to use this tool
CIDR prefix
An IPv4 prefix /n fixes n network bits out of 32. Total addresses = 2^(32−n).
Network and broadcast
The network address has all host bits zero; the traditional broadcast address has all host bits one.
Usable hosts
The old total−2 shortcut has exceptions such as /31 point-to-point networks and /32 single-host routes, so implementations should label semantics carefully.
Examples
Worked example
A /24 contains 2^8 = 256 total IPv4 addresses.
Common use cases
- Plan subnets
- Check CIDR blocks
- Verify masks
- Calculate address ranges
Frequently asked questions
How many addresses are in a /24?
256 total addresses.
What is a subnet mask for?
It separates network bits from host bits.
Is usable hosts always total minus two?
No.
What does /32 mean?
A single IPv4 address prefix.
Does this tell me who owns the IP range?
No.