IPv4 CIDR Calculator (subnet, network and broadcast)
Calculate the network address, broadcast address, usable host range, subnet mask, wildcard mask and address count from an IPv4 address and prefix length, including /31 and /32.
- Runs in your browser (no upload)
Example: 192.168.10.37/26. You can also enter a subnet mask after "/" (such as 255.255.255.0).
Result
Network 192.168.10.0/26, 62 usable hosts
The address 192.168.10.37 belongs to the network 192.168.10.0/26.
Binary
- Address
- 11000000.10101000.00001010.00100101
- Mask
- 11111111.11111111.11111111.11000000
Bold digits are the network part (26 bits); the rest is the host part (6 bits).
How to use
- Enter an IPv4 address with its prefix length, such as 192.168.10.37/26 (a subnet mask after "/" also works).
- The network address, broadcast address, usable range, masks and address counts appear instantly.
- Press "Copy" to copy all results at once.
FAQ
Why does a /31 have 2 usable addresses?
RFC 3021 allows a /31 on point-to-point links: both addresses are host addresses and there is no broadcast address. So instead of the usual "total minus 2", a /31 has 2 usable hosts.
What does /32 mean?
It is a prefix covering exactly one address (a host route). It has 1 address and no separate network or broadcast address.
Why is "192.168.001.010" rejected?
Some implementations such as inet_addr() read a number with a leading zero as octal (010 becomes 8), which silently gives a different address. To avoid that ambiguity, enter the numbers without leading zeros.
What is a wildcard mask?
It is the subnet mask with every bit inverted (255.255.255.192 becomes 0.0.0.63). Router access lists often use it.
Notes & limitations
- What you enter is processed only on this page and is not sent to YUCTS servers.
- IPv4 only; IPv6 is not supported.
- Only dotted-decimal input such as 192.168.1.10/24 is accepted. Shorthand (127.1), hexadecimal, octal and plain integer forms are not supported.
- A /31 is calculated as defined in RFC 3021. Whether it works in practice depends on your devices and operating systems.
- The tool does not tell whether an address is private, reserved or public.
Data sources
- RFC 4632 — Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan(opens in a new tab) (BCP 122, August 2006) — Checked on: 2026-11-06
- RFC 3021 — Using 31-Bit Prefixes on IPv4 Point-to-Point Links(opens in a new tab) (December 2000) — Checked on: 2026-11-06
- RFC 6943 — Issues in Identifier Comparison for Security Purposes (§3.1.1 IPv4 literals)(opens in a new tab) (May 2013) — Checked on: 2026-11-06
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