IPv4 Subnet Calculator
Instant results as you type.
/n
Network
192.168.1.0/24
Subnet mask255.255.255.0
Wildcard mask0.0.0.255
Broadcast192.168.1.255
Usable host range192.168.1.1 – 192.168.1.254
Usable hosts254
Total addresses256
Whole block192.168.1.0 – 192.168.1.255
Bit split24 network bits · 8 host bits
Address classClass C · first octet 192–223 · classful default mask /24 (255.255.255.0)
Address typePrivate — RFC 1918; usable inside your own network, never routed on the public internet
Address in binary11000000.10101000.00000001.00001010
Mask in binary11111111.11111111.11111111.00000000
Address in hex and decimal0xC0A8010A · C0.A8.01.0A · 3232235786 decimal
Reverse DNS (PTR)10.1.168.192.in-addr.arpa
IPv4-mapped IPv6::ffff:192.168.1.10
Next block192.168.2.0/24
An IPv4 subnet calculator turns an address and prefix into everything you need to plan a network: the network address, subnet mask, wildcard mask, broadcast address, usable host range, host counts, the classful first-octet range, and whether the address is private, loopback, link-local, multicast or reserved. It also writes the address in binary, hex and decimal, gives the reverse-DNS name, and splits a block such as 192.168.0.0/16 into as many subnets as you ask for. Special cases like /31 point-to-point links and /32 host routes are handled correctly, and nothing you type leaves your browser.
How to use it
- Enter an IPv4 address, such as 192.168.1.10. A whole CIDR block like 192.168.0.0/16, a 0xC0A8010A hex address, or a plain integer all work too.
- Set the prefix length — /24 is the common default for a small network.
- Read off the network, mask, broadcast, host range, address class, address type, and the binary, hex and decimal forms.
- To carve the block up, put the number of subnets you want in Split into subnets; the first eight are listed with their host ranges.
Examples
- 192.168.1.10/24 → network 192.168.1.0, broadcast 192.168.1.255, 254 usable hosts, Class C, private (RFC 1918).
- 172.16.5.200/27 → network 172.16.5.192, 30 usable hosts.
- 192.168.0.0/16 split into 256 → 256 subnets of /24, first 192.168.0.0/24, last 192.168.255.0/24.
Frequently asked questions
- What does the /24 prefix mean?
- The prefix is how many bits from the left identify the network rather than the host. A /24 fixes the first 24 bits, leaving 8 bits for hosts — that's a 255.255.255.0 mask and 256 total addresses, of which 254 are usable.
- Why are 2 addresses unusable in most subnets?
- The first address in a subnet identifies the network itself and the last is the broadcast address, so neither can be assigned to a device. That's why a /24 gives 254 usable hosts rather than 256.
- How do /31 point-to-point links work?
- RFC 3021 allows /31 subnets on point-to-point links, where the usual network and broadcast addresses are dispensed with and both addresses are usable. This calculator follows that rule, so a /31 correctly shows 2 usable hosts rather than none.
- How do I split a network into smaller subnets?
- Type how many you want into Split into subnets and the calculator works out the prefix for you, then lists the first eight with their usable ranges and broadcast addresses. Counts are always powers of two, so a request for 3 is answered with 4; each extra bit halves the block and doubles the number of subnets.
- What are IPv4 address classes and the first-octet ranges?
- The first octet decides the class: 0–127 is Class A with a default /8 mask, 128–191 is Class B with /16, 192–223 is Class C with /24, 224–239 is Class D for multicast, and 240–255 is Class E, reserved. Classful routing was replaced by CIDR in 1993, so the prefix you set is what actually applies — but the class vocabulary survives in exams, vendor documentation and everyday conversation.
- How do I convert an IP address to hex, binary, or decimal?
- Each of the four octets becomes two hex digits or eight binary digits, and the whole address is one 32-bit unsigned integer. 192.168.1.10 is 0xC0A8010A in hex, 11000000.10101000.00000001.00001010 in binary, and 3232235786 as a decimal integer. The calculator shows all three at once, and it also accepts the hex and decimal forms as input.
- Which IPv4 ranges are private or reserved?
- RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 for private use. Other blocks you will meet: 127.0.0.0/8 loopback, 169.254.0.0/16 link-local (APIPA), 100.64.0.0/10 carrier-grade NAT, 224.0.0.0/4 multicast, 240.0.0.0/4 reserved, and the documentation ranges 192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24. The calculator names whichever one your address falls in.
- How many /24 subnets fit in a 192.168.0.0/16?
- 256. Going from /16 to /24 adds eight bits to the prefix, and two to the power of eight is 256 — running from 192.168.0.0/24 to 192.168.255.0/24, each with 254 usable host addresses. Set Split into subnets to 256 and the calculator lists them for you.