Free developer tool
IPv4 Subnet Calculator
CIDR notation writes a network as an address and a prefix length, such as 192.168.1.0/24. The prefix says how many of the 32 bits belong to the network.
IPv4 Calculator
Convert IPv4 CIDR notation.
Network
192.128.0.0/10
Netmask
255.192.0.0
Broadcast
192.191.255.255
Wildcard
0.63.255.255
First host
192.128.0.1
Last host
192.191.255.254
Usable hosts
4194302
Address range
192.128.0.0 - 192.191.255.255
About this tool
This calculator turns that into the numbers you need to plan a network or write a firewall rule: the network address, netmask, broadcast address, wildcard mask, first and last usable host, and how many hosts fit.
How to use it
- Type an IPv4 address with a prefix, for example 10.0.0.15/22.
- Read the results as you type; each value has a copy button.
What the results mean
- Network
- The first address of the block, with the prefix length.
- Netmask
- The prefix written as an address, such as 255.255.255.0 for /24.
- Broadcast
- The last address of the block.
- Wildcard
- The inverse of the netmask, used in Cisco ACLs and some firewall rules.
- First and last host
- The usable range for devices. For /31 and /32 the whole block is usable.
- Usable hosts
- How many devices the block can hold.
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