IPv4 Subnet Calculator: CIDR, Masks & Host Ranges
Work out the network address, broadcast address, usable host range, subnet and wildcard masks for any IPv4 block, then divide it into smaller subnets. Enter an address and prefix length to plan VLANs, DMZs and point-to-point links before you configure a switch or firewall.
- Free, no sign-up
- CIDR /0 to /32
- Runs in your browser
- Shareable link
Network
Any address in the block works; the network address is worked out for you.
Results
192.168.10.0/24The network and broadcast addresses are reserved, so a /24 gives 254 hosts. Entered address 192.168.10.0 is the network address itself.
11000000.10101000.00001010.0000000011111111.11111111.11111111.000000000xC0A80A00 · 3232238080Subnets
| # | Network | Host range | Broadcast | Hosts | Open |
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CIDR prefixes compared
Live values for 192.168.10.0| Prefix | Subnet mask | Wildcard | Addresses | Usable hosts | Typical use | Select |
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Usable hosts exclude the network and broadcast addresses. A /31 keeps both addresses for a point-to-point link (RFC 3021) and a /32 is a single host. Reserve one address per subnet for the gateway.
Subnet calculator FAQ
What is CIDR notation?
Classless Inter-Domain Routing writes a network as an address followed by a slash and the number of bits in the network part, for example 192.168.10.0/24. The prefix length replaces the old class A, B and C boundaries, so a block can be any power-of-two size: /24 is 256 addresses, /26 is 64, /30 is 4.
How many usable hosts are in a /24?
254. A /24 has 256 addresses, but the first is the network address and the last is the broadcast address, and neither can be assigned to a device. In practice one more goes to the default gateway, leaving 253 for hosts.
Why does the calculator subtract two addresses?
Every IPv4 subnet reserves its lowest address to identify the network and its highest for broadcast traffic. The exceptions are /31, which RFC 3021 allows on point-to-point links with both addresses usable, and /32, which is a single host route.
Which IP ranges are private?
RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 for private networks. They are never routed on the public internet, so they need NAT at the edge. 100.64.0.0/10 is carrier-grade NAT space, 169.254.0.0/16 is link-local and 127.0.0.0/8 is loopback.
What is a wildcard mask?
The inverse of the subnet mask, with the host bits set to one. Cisco access lists and OSPF network statements use it: a /24 has subnet mask 255.255.255.0 and wildcard mask 0.0.0.255. The calculator shows both.
How do I split a network into smaller subnets?
Borrow host bits. Each extra bit of prefix doubles the number of subnets and halves their size, so a /24 becomes two /25s of 126 hosts or four /26s of 62 hosts. Choose a prefix in Divide into subnets and the table lists every resulting block with its host range and broadcast address.