IP Subnet Calculator (IPv4 CIDR)
Network and broadcast address, subnet mask, wildcard, usable host range and host count for any IPv4 CIDR block.
Result
How to use
- 1
Enter an IPv4 address with a CIDR prefix (/24) or a dotted subnet mask.
- 2
Read the network, broadcast, mask and usable host range.
- 3
Optionally split the block into equal smaller subnets.
Questions
How many hosts are in a /24?
A /24 has 256 addresses; the first is the network address and the last is the broadcast, leaving 254 usable hosts. In general a /n network has 2^(32−n) addresses and 2^(32−n) − 2 usable hosts.
Why does /31 show 2 usable hosts?
RFC 3021 allows /31 networks on point-to-point links, where both addresses are usable and there is no broadcast. A /32 is a single host.
Which IP ranges are private?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 (RFC 1918) are private and used in homes and offices. 100.64.0.0/10 is carrier-grade NAT, used by many Indian ISPs and mobile networks.
About this Subnet tool
IP Subnet Calculator (IPv4 CIDR) — Network and broadcast address, subnet mask, wildcard, usable host range and host count for any IPv4 CIDR block. It is one of 200 free tools on namasivayam.in, made by software engineer Namasivayam Vadivelan for everyday use in India.
Everything is calculated instantly in your browser: nothing you type or upload is sent to any server, there is no sign-up, and it works on mobile and desktop. Enter an IPv4 address with a CIDR prefix (/24) or a dotted subnet mask.
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Results are estimates to help you plan. They are not financial, tax or medical advice.