CIDR calculator
Turn a CIDR block into its subnet mask, wildcard, address range, network, broadcast and host count — live, with the bit-level breakdown. Type a CIDR like 10.0.0.0/22 to start.
1 · IP address
2 · Prefix / mask
3 · Split into subnets
Divides this block into 4 × /24 subnets. Need different sizes? Use the VLSM calculator →
CIDR — common questions
What is CIDR notation?
Classless Inter-Domain Routing (CIDR) writes a network as an address plus a prefix length, like 192.168.1.0/24. The /24 means the first 24 bits are the network portion. It replaced the old A/B/C class system, letting networks be any size rather than fixed blocks. This calculator turns any CIDR into its mask, range and host count.
How do I convert CIDR to an IP range?
The prefix fixes the network bits; the remaining host bits give the range. 192.168.1.0/24 covers 192.168.1.0–192.168.1.255 (256 addresses, 254 usable). Type any CIDR (or IP + mask) above and the network, broadcast and usable range appear instantly, with the bit-grid showing the split.
How do I convert CIDR to a subnet mask?
Count the prefix as leading 1-bits: /24 = 255.255.255.0, /26 = 255.255.255.192, /30 = 255.255.255.252. The calculator shows the mask and wildcard for any prefix, and the cheat sheet lists them all.
Can I split a CIDR block into smaller subnets?
Yes — set the “split into” prefix and the tool lists the child subnets (e.g. a /24 into four /26s). For subnets of different sizes from one block, use the VLSM calculator.