IP Subnet Calculator
Type an IPv4 address in CIDR notation (192.168.1.10/24) or with its mask: network, broadcast, host range and subnetting appear instantly.
Address and mask
Ignored if the address contains “/prefix”
Network
—
Binary notation
Bold: network bits; light: host bits.
Split into subnets
| Subnet | Usable range | Broadcast |
|---|
About subnet calculation
A subnet mask splits an IPv4 address into two parts: the network bits, shared by every machine in the subnet, and the host bits, unique to each. CIDR notation (/24) gives the number of network bits: /24 is the mask 255.255.255.0 with 254 usable hosts.
Features
- Complete results: network address, broadcast, netmask, wildcard mask, first and last host
- Host and address count, legacy class, address type (private, public, CGNAT, loopback…)
- Binary view separating network bits and host bits
- Subnetting: list of smaller subnets (up to 256 shown)
- Special cases: /31 (point-to-point, RFC 3021) and /32
How to use
- Step 1: type an address with its prefix (10.0.0.0/8) or separately with the mask
- Step 2: read the network information
- Step 3: choose a longer prefix to split the network
Quick reference
- /24: 255.255.255.0 · 254 hosts
- /16: 255.255.0.0 · 65,534 hosts
- /30: 255.255.255.252 · 2 hosts
- Private networks: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
Use cases
- Set up a home or office network, a VLAN, a VPN
- Write a firewall rule or an access list (wildcard)
- Study for networking exams (CCNA, Network+)
- Split an address block between several sites
Privacy
Everything is computed in your browser: the data you enter is never sent anywhere and we never have access to it. Internal data can be pasted safely.