Turn a CIDR block into its address range, mask, and host count.
Tip: use samples, upload, copy, download, and send-to actions inside the workspace where available.
CIDR Calculator is a free, browser-based tool that helps you convert between formats. Turn a CIDR block into its address range, mask, and host count. It's built for speed and privacy: Everything runs locally in your browser — your data is never uploaded to a server. No sign-up, no installs, and no daily limits.
Start with the source file or pasted payload, then confirm delimiters, headers, and field handling before conversion.
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Subnet Calculator: Plan subnets: network, usable range, broadcast, and mask.
Open toolIPv4 Subnet Calculator: Network, broadcast, host range, mask, and class from an IP + prefix.
Open toolIPv6 Calculator: Expand, compress, and derive the reverse-DNS of any IPv6 address.
Open toolHow this was calculated: the mask is 22 one-bits followed by 10 zero-bits, which is 255.255.252.0 in dotted decimal. AND-ing the address with the mask clears every host bit and yields the network address; OR-ing with the inverted mask sets them all and yields the broadcast address. Total addresses = 210 = 1,024, minus the network and broadcast addresses for the usable count.
Largest private block: 16,777,216 addresses. Reference: RFC 1918.
This block is the lower half of 10.0.0.0/21, so it can be merged (supernetted) with 10.0.4.0/22 into a single route.
| # | Subnet | Network | First host | Last host | Broadcast | Hosts | |
|---|---|---|---|---|---|---|---|
| 1 | 10.0.0.0/24 | 10.0.0.0 | 10.0.0.1 | 10.0.0.254 | 10.0.0.255 | 254 | |
| 2 | 10.0.1.0/24 | 10.0.1.0 | 10.0.1.1 | 10.0.1.254 | 10.0.1.255 | 254 | |
| 3 | 10.0.2.0/24 | 10.0.2.0 | 10.0.2.1 | 10.0.2.254 | 10.0.2.255 | 254 | |
| 4 | 10.0.3.0/24 | 10.0.3.0 | 10.0.3.1 | 10.0.3.254 | 10.0.3.255 | 254 |
Borrowing 2 host bits creates 22 = 4 subnets. Each subnet loses two addresses to its own network and broadcast entries, which is why splitting reduces total usable host count.
