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IP Subnet Calculator – CIDR, Netmask & Host Range

Calculate IPv4 subnets: network and broadcast address, usable host range, subnet and wildcard masks, host count, and split networks into smaller subnets.

  • Free, no sign-up
  • Runs in your browser, nothing uploaded

About the Subnet Calculator

Work out any IPv4 subnet from an address and a CIDR prefix or netmask. See the network and broadcast addresses, the usable host range and count, masks in dotted and binary form, and split a network into equal subnets.

Key features

  • CIDR or dotted netmask input
  • Network, broadcast, host range
  • Subnet and wildcard masks
  • Binary and hex views
  • Split into equal subnets
  • Private, public and special ranges

Plan networks without the binary math

Subnetting splits an IP range into smaller networks. Enter an address with its prefix or mask to see the full range, or split a block into equal subnets for VLANs, offices or cloud networks.

Common subnet sizes

CIDRSubnet maskUsable hostsTypical use
/30255.255.255.2522Router-to-router links
/29255.255.255.2486Small static IP blocks
/28255.255.255.24014Small office segment
/27255.255.255.22430Department VLAN
/24255.255.255.0254Home or office LAN
/22255.255.252.01,022Campus network
/16255.255.0.065,534Cloud VPC

What is my IP, number base converter and DNS lookup.

How to use the Subnet Calculator

  1. Enter an IPv4 address with a prefix (192.168.1.10/24) or a subnet mask.
  2. Or pick the prefix from the list.
  3. Read the network, broadcast, host range, masks and host count instantly.
  4. Choose a smaller prefix to split the network into subnets.

Frequently asked questions

What does /24 mean?

It's CIDR notation: the first 24 bits of the address identify the network and the remaining 8 identify hosts. A /24 equals the mask 255.255.255.0 and has 256 addresses, 254 of them usable.

Why are there two fewer usable hosts?

The first address is the network address and the last is the broadcast address, so neither can be given to a device. /31 (point-to-point links) and /32 (a single host) are exceptions.

What is a wildcard mask?

The inverse of the subnet mask, used in Cisco access lists and OSPF. For 255.255.255.0 the wildcard is 0.0.0.255.

Which IP ranges are private?

10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 (RFC 1918). They're used inside homes and offices and aren't reachable directly from the internet.

Are these network tools free?

Yes. All tools are free with no sign-up. To keep them fast for everyone, each visitor can run about 30 checks of each kind every five minutes.

Do you store the domains I check?

No. Lookups are run on demand and the results aren't saved. Your own IP address isn't stored either.

Where do the results come from?

DNS lookups query public resolvers (Cloudflare, Google and Quad9), WHOIS data comes from each registry's official RDAP or WHOIS service, and SSL and HTTP checks connect to the website directly from our server.

Can I check sites on my local network?

No. For security, our server only connects to public internet addresses, so localhost, 192.168.x.x and other private addresses are refused. The subnet calculator works with any address because it runs in your browser.

Last updated:

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