IP Range Calculator
Work out everything about an IPv4 network in one step. Type a network in CIDR notation, an address with a subnet mask, or a start and end address, and get the network and broadcast addresses, the usable host range, the masks and an optional list of subnets.
- Runs in your browser
- No sign-up
- Free to use
Examples: 10.0.0.0/8 · 192.168.1.10 255.255.255.0 · 192.168.1.10 - 192.168.1.50
How to use IP Range Calculator
- Enter a network such as 192.168.1.0/24, an address followed by a mask, or a range written as start - end.
- Read the network address, the usable range and the number of hosts.
- To divide the network, choose a prefix under Split into subnets.
- Copy individual values with the copy buttons, or download the subnet list as a CSV file.
IP Range Calculator features
Three input styles
CIDR notation, address plus dotted or wildcard mask, and start–end ranges.
Complete network facts
Network, broadcast, first and last host, total and usable addresses, subnet and wildcard mask.
Range to CIDR
Converts any start and end address into the smallest set of CIDR blocks that covers it exactly.
Subnet splitting
Divides a network into equal subnets and lists each one with its range and broadcast address.
Binary and integer views
The mask and network in binary, plus the integer and hexadecimal value of the address.
Address type
Recognises private, loopback, link-local, carrier-grade NAT, multicast and documentation ranges.
When to use IP Range Calculator
- Planning the address layout of an office, a lab or a cloud network.
- Turning a provider's address range into CIDR blocks for a firewall rule or an allow list.
- Checking whether two devices are in the same subnet.
- Learning or teaching subnetting with instant feedback.
IP Range Calculator FAQ
What does the number after the slash mean?
It is the prefix length: the number of leading bits that identify the network. In 192.168.1.0/24 the first 24 bits are the network and the remaining 8 bits number the hosts, giving 256 addresses. Every step down in prefix length doubles the size of the network.
Why are two addresses not usable?
In a normal subnet the first address identifies the network itself and the last one is the broadcast address, which reaches all hosts. A /24 therefore has 254 usable addresses out of 256. The exceptions are /31, used for point-to-point links where both addresses are usable, and /32, a single host.
What is a wildcard mask?
The inverse of the subnet mask: 0.0.0.255 for a /24. It is used in access control lists on Cisco equipment and in OSPF configuration, where a 0 bit means “must match” and a 1 bit means “any value”.
How does range to CIDR conversion work?
A CIDR block must start on a boundary that matches its size, so an arbitrary range usually needs several blocks. The calculator repeatedly takes the largest block that starts at the current address and still fits in the range. The result is the shortest exact list, with no addresses outside the range.
Which ranges are private?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are reserved for private networks and are not routed on the internet. 100.64.0.0/10 is shared space used by providers for carrier-grade NAT, and 169.254.0.0/16 is used for self-assigned link-local addresses.
Does it support IPv6?
This calculator is for IPv4. For IPv6 prefixes, use the IPv6 Address Calculator, which handles the much larger numbers involved.
A short guide to IPv4 subnetting
An IPv4 address is a 32-bit number, written as four decimal values so that people can read it. A subnet mask divides those 32 bits into a network part and a host part. All devices whose addresses share the same network part are in the same subnet and can reach each other directly; traffic to any other network goes through a router. CIDR notation states the split compactly: the address followed by a slash and the number of network bits.
The arithmetic follows from the host bits. With h host bits there are two to the power of h addresses, and two fewer usable ones. A /24 leaves 8 host bits and 254 hosts, a /26 leaves 6 bits and 62 hosts, a /30 leaves 2 bits and exactly 2 hosts, which is why /30 was long the standard for links between two routers. The network address has all host bits set to zero, the broadcast address has them all set to one.
Subnetting means moving the boundary to the right. Borrowing two bits from the host part of a /24 produces four /26 networks, starting at .0, .64, .128 and .192. The useful trick is that subnets always start at a multiple of their own size, so the block size tells you every boundary without further calculation. The split view in this tool lists those boundaries for any prefix.
When choosing sizes, plan for growth and keep things regular. A subnet that is exactly full cannot take one more device, and re-addressing a live network is tedious. Giving each site or function a block with room to spare, aligned on boundaries that can later be summarised into one larger prefix, keeps routing tables and firewall rules short.