Subnet Calculator
Enter an IPv4 address and CIDR prefix length to get the subnet mask, network and broadcast addresses, usable host range, and total address count for that network.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Network
192.168.1.0/24
Summary
The network 192.168.1.0/24 has a subnet mask of 255.255.255.0, spans 256 total addresses, and provides 254 usable host addresses from 192.168.1.1 to 192.168.1.254. The broadcast address is 192.168.1.255.
Subnet Mask
255.255.255.0
Wildcard Mask
0.0.0.255
Broadcast Address
192.168.1.255
IP Class
C
First Usable Host
192.168.1.1
Last Usable Host
192.168.1.254
Total Addresses
256
Usable Hosts
254
Usable host addresses vs. reserved network/broadcast addresses
- Usable: 254
- Reserved: 2
What is a Subnet Calculator?
A subnet calculator computes the key details of an IPv4 network from an IP address and a CIDR prefix length (like the /24 in 192.168.1.0/24): the subnet mask, the network and broadcast addresses, the range of usable host addresses, and the total number of addresses the subnet contains. Subnetting is the process of dividing a larger network into smaller, more manageable pieces — used constantly in network design, from home routers to enterprise data centers.
Every device on an IP network needs to know which part of an address identifies the network and which part identifies the specific host — the subnet mask (or equivalently, the CIDR prefix length) defines that split. This calculator does all of the binary arithmetic for you.
Nearby Prefix Lengths for 192.168.1.0
See how the address count and usable hosts scale as the prefix length changes around your current /24.
| CIDR | Subnet Mask | Total Addresses | Usable Hosts |
|---|---|---|---|
| /20 | 255.255.240.0 | 4,096 | 4,094 |
| /21 | 255.255.248.0 | 2,048 | 2,046 |
| /22 | 255.255.252.0 | 1,024 | 1,022 |
| /23 | 255.255.254.0 | 512 | 510 |
| /24 (current) | 255.255.255.0 | 256 | 254 |
| /25 | 255.255.255.128 | 128 | 126 |
| /26 | 255.255.255.192 | 64 | 62 |
| /27 | 255.255.255.224 | 32 | 30 |
| /28 | 255.255.255.240 | 16 | 14 |
How Subnetting Works
An IPv4 address is 32 bits long, written as four 8-bit octets. The CIDR prefix length says how many of those 32 bits, counting from the left, belong to the network portion — the rest belong to the host portion:
The subnet mask is simply that many leading 1 bits followed by 0 bits, written in the same dotted-decimal form as an IP address. ANDing an IP address with the subnet mask zeroes out the host bits and gives the network address; ORing the network address with the inverse of the mask (the wildcard mask) sets all host bits to 1 and gives the broadcast address.
| IP Address | 11000000.10101000.00000001.00000000 |
| Subnet Mask | 11111111.11111111.11111111.00000000 |
Why Two Addresses Are Reserved
In a standard subnet (prefix length /30 or shorter), the very first address (all host bits 0) is reserved as the network address — it identifies the subnet itself and can't be assigned to a device — and the very last address (all host bits 1) is reserved as the broadcast address, used to send a packet to every host on the subnet at once. That leaves total addresses minus 2 as usable host addresses.
The /31 and /32 Special Cases
A /31 network (only 2 total addresses) is a documented exception (RFC 3021): since there's no room for both a network and broadcast address alongside any usable hosts, both addresses are treated as usable — commonly used for point-to-point links between two routers. A /32 identifies a single specific address (a "host route") with no network or broadcast concept at all.
Why Subnet Your Network at All
Subnetting lets you carve a large address block into smaller networks that match your actual topology — separating departments, floors, or device types (servers, printers, guest Wi-Fi) into their own broadcast domains. This limits broadcast traffic, improves security by isolating segments with firewall rules between them, and lets you allocate exactly as many addresses as a segment needs instead of wasting a huge flat address space on it.
Example — Your Current Inputs
The network 192.168.1.0/24 has a subnet mask of 255.255.255.0, spans 256 total addresses, and provides 254 usable host addresses from 192.168.1.1 to 192.168.1.254. The broadcast address is 192.168.1.255.
Additional Example — A Small Office Network
A small office is assigned 10.0.0.0/26. That's a 6-bit host portion, giving 2^6 = 64 total addresses: 10.0.0.0 (network), 10.0.0.63 (broadcast), and 62 usable addresses from 10.0.0.1 through 10.0.0.62 — enough for a few dozen desks, printers, and access points without wasting the hundreds of addresses a /24 would provide.
About These Parameters
- IP Address
- Any IPv4 address that falls within the network you're analyzing, in standard dotted-decimal form (four numbers 0-255 separated by periods). It does not need to already be the network address — the calculator derives that for you.
- CIDR Prefix Length
- The number of network bits, from 0 to 32. Smaller numbers describe larger networks with more hosts (a /8 has millions of addresses); larger numbers describe smaller, more specific subnets (a /30 has only 4 addresses, 2 of them usable).
Frequently Asked Questions
What's the difference between a subnet mask and a CIDR prefix?
They express exactly the same information in two notations. A CIDR prefix like /24 counts the number of leading 1 bits directly; a subnet mask like 255.255.255.0 writes those same bits out in dotted-decimal form. Every CIDR prefix has exactly one equivalent subnet mask.
Why can't I use the network or broadcast address for a device?
Both addresses have a reserved meaning at the protocol level: the network address identifies the subnet as a whole, and the broadcast address is used to reach every host on the subnet simultaneously. Assigning either to a single device would create ambiguity that routers and switches aren't built to handle.
Does this calculator support IPv6?
No, this calculator covers IPv4 addressing only. IPv6 uses a much larger 128-bit address space with different subnetting conventions and typically doesn't reserve a broadcast address the same way IPv4 does.
What is a wildcard mask used for?
A wildcard mask is the bitwise inverse of the subnet mask, and is used by some router and firewall configuration syntaxes (notably Cisco access control lists) instead of a subnet mask. It marks which bits are allowed to vary (1) versus which must match exactly (0), which is the opposite convention from a subnet mask.