IP Subnet Calculator
Calculate network address, broadcast, range and usable hosts for IPv4 CIDR
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IP Subnet Calculator helps you calculate network address, broadcast, range and usable hosts for IPv4 CIDR without a spreadsheet. You supply IP Address and Prefix Length (/24) to IP Subnet; the answer follows at once. IP Subnet ties each output to its formula. Students and professionals reach for IP Subnet when speed matters. IP Subnet runs in your browser. Tech & Digital data stays in the tab. IP Subnet sits in the Tech & Digital section next to free online ip subnet calculator and ip subnet calculator. IP Subnet goes from question to answer fast. IP Subnet answers the next Tech & Digital question you meet.
What /24 means for this address
For 192.168.1.10 with a /24 prefix the network address is 192.168.1.0, the mask 255.255.255.0, the broadcast 192.168.1.255 and the usable range 192.168.1.1 – 192.168.1.254: 254 hosts.
The prefix is the number of leading bits fixed as network; /24 fixes 24 of 32, leaving 8 host bits, and 2⁸ = 256 addresses in the block.
The arithmetic
An IPv4 address is 32 bits. The prefix length says how many are locked to the network, so host bits = 32 − prefix. For /24 that is 8 bits, and addresses = 28 = 256. Remove the network address (all host bits 0) and the broadcast (all host bits 1) and 254 remain usable.
The mask is those leading bits set to 1: /24 → 255.255.255.0. Network address is the IP ANDed with the mask; broadcast is the network with every host bit set to 1.
Worked example: 192.168.1.10/24
IP in binary: 11000000.10101000.00000001.00001010
Mask /24: 11111111.11111111.11111111.00000000
Network: 11000000.10101000.00000001.00000000 = 192.168.1.0
Broadcast: 11000000.10101000.00000001.11111111 = 192.168.1.255
Hosts: 192.168.1.1 to 192.168.1.254
Common prefixes at a glance
- /30 — 4 addresses, 2 usable. Point-to-point links.
- /29 — 8 addresses, 6 usable. Small server segments.
- /28 — 16 addresses, 14 usable.
- /26 — 64 addresses, 62 usable. A floor of a small office.
- /24 — 256 addresses, 254 usable. The classic home or small-office LAN.
- /16 — 65,536 addresses. A whole private 172.16–172.31 block.
Where the two-address rule breaks
/31 (RFC 3021) provides two usable addresses on a point-to-point link, and /32 is a single host route with none. Above /30 the subtraction applies as normal. Getting this wrong is why a /31 link sometimes “loses” both ends.
Mistakes worth avoiding
- Counting the network and broadcast as usable. 256 addresses is not 256 hosts.
- Assuming any 192.168.x.x is one LAN. /24 splits it into 256 separate /24s if the mask says /16 instead.
- Overlapping subnets on a VPN. 192.168.1.0/24 at home and in the office is the classic clash — renumber one side.
- Forgetting that a host can reach only its own subnet directly; everything else has to go through the gateway.
Frequently Asked Questions
Why 254 usable hosts rather than 256?
A /24 holds 256 addresses. The first, with all host bits zero, names the network itself; the last, all host bits one, is the broadcast. Neither can be assigned to a device.
What is the subnet mask for /24?
255.255.255.0 — the first 24 bits set to 1 and the last 8 to 0. Every prefix has exactly one mask, so the mask never needs to be entered separately.
How many addresses in a /26?
64 — 2^6, because six host bits remain. That gives 62 usable hosts after the network and broadcast addresses.
Is 192.168.1.255 always broadcast?
Only within a /24. With a /16 mask it is an ordinary host address, because the broadcast for that block is 192.168.255.255. The mask decides, not the last octet.
Can I use /31 for a router-to-router link?
Yes — RFC 3021 allows /31 on point-to-point links and both addresses are usable. It saves two addresses per link compared with /30, which is why modern point-to-point configs use it.
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