Subnet Calculator
Calculate subnet masks, network addresses, broadcast addresses, and IP ranges
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Subnet Information
Common Networks
Network Results
Network Information
Binary Representation
Subnet List
| # | Network | First Host | Last Host | Broadcast | Hosts |
|---|
Conversion Result
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How to Use the Subnet Calculator
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Subnet Info
Calculate network details from any IP address and subnet mask
Subnet Division
Divide a network into smaller subnets for better organization
CIDR Lookup
Convert between CIDR notation and decimal subnet masks
Authoritative sources and references
The official standards, guidelines, and research behind this calculator's methodology.
Subnet Calculator FAQ
What is CIDR notation and how do I use it?
CIDR notation appends a slash and a bit count to an IP address, such as 192.168.1.0/24. The number shows how many bits belong to the network portion, which directly determines how many host addresses are available.
How many usable hosts are in a /26 subnet?
A /26 subnet contains 64 total addresses, of which 62 are usable after reserving the network address and the broadcast address. The calculator lists the full range automatically.
What are the network and broadcast addresses used for?
The network address identifies the subnet itself and the broadcast address reaches every host in it. Neither can be assigned to a device, which is why they are subtracted from usable host counts.
How do I split a /24 into four equal subnets?
Borrow 2 bits from the host portion: /24 → four /26 subnets, each with 64 addresses (62 usable). For 192.168.10.0/24 the blocks are 192.168.10.0/26, .64/26, .128/26, and .192/26 — the calculator lists network, broadcast, and usable ranges for each.
What are the private address ranges I can use at home?
RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 for private use, and RFC 4193 reserves fc00::/7 for private IPv6. Anything inside these blocks never routes on the public internet, which is why every home router hands out 192.168.x.x or 10.x.x.x addresses.
How do I compute the number of subnets for a new mask?
Each bit borrowed from hosts doubles the subnet count: moving from /24 to /27 borrows 3 bits, giving 2³ = 8 subnets of 32 addresses (30 usable) each. The trade is always two-to-one: every doubling of subnet count halves the addresses per subnet.
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