How many usable hosts are in a /26 subnet?

A /26 has 2^(32−26) = 64 total addresses. Subtract the network and broadcast addresses and you get 62 usable hosts. The mask is 255.255.255.192 and the block size is 64, so networks fall on .0, .64, .128, and .192.

What is the subnet mask for a /26?

255.255.255.192. A /26 sets the first 26 bits of the mask to 1. That fills the first three octets (24 bits) plus the top two bits of the fourth octet (128 + 64 = 192), giving 255.255.255.192 and a wildcard of 0.0.0.63.

How do I find the network and broadcast address from an IP and prefix?

Convert the IP to 32 bits, build the mask from the prefix, then AND them: network = IP AND mask. The broadcast is the network OR the wildcard (the inverted mask). For 192.168.10.130/26 that gives network 192.168.10.128 and broadcast 192.168.10.191.

What is the difference between CIDR /24 and a 255.255.255.0 mask?

None — they are two ways of writing the same thing. /24 means 24 leading 1-bits in the mask, which is 255.255.255.0 in dotted-decimal. CIDR notation (RFC 4632) just counts the 1-bits instead of spelling out each octet. This tool shows both and keeps them in sync.

Which IPv4 ranges are private (RFC 1918)?

Three blocks: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Addresses in these ranges are not routed on the public internet and are reused inside home and office networks. This calculator flags any address that falls inside them.

Why do /31 and /32 subnets show a different host count?

A /31 (RFC 3021) is used on point-to-point links: both of its two addresses are usable, with no network or broadcast reserved. A /32 is a single host route — one address, usable by itself. For every prefix /30 and shorter, two addresses are reserved (network and broadcast).

What is a wildcard mask used for?

A wildcard mask is the bitwise inverse of the subnet mask (for /26 it is 0.0.0.63). Cisco access-control lists and OSPF network statements match on wildcard masks rather than subnet masks, so network engineers need both. The tool shows the wildcard alongside the mask.

Is my IP data sent anywhere?

No. Every calculation is pure bit math done in your browser with JavaScript. No address you type leaves your device, there is no server call, and nothing is logged. You can disconnect from the network and the calculator still works.

What is CGNAT (100.64.0.0/10) and why does my router show it?

100.64.0.0/10 is Carrier-Grade NAT space defined in RFC 6598. ISPs use it to share a pool of public addresses across many subscribers. If your WAN IP starts with 100.64–100.127, you are behind CGNAT, which can affect port forwarding and self-hosting.

Developer · Networking

IP Subnet Calculator (CIDR / IPv4)

Enter an IPv4 address and a CIDR prefix to get the network and broadcast addresses, usable host range, host count, subnet mask, wildcard, IP class and address type — and split a block into equal subnets. Pure bit math, runs entirely in your browser, no signup.

By Induwara Ashinsana— Executive Director, Ryzera TechnologiesUpdated Jun 8, 2026

Subnet calculatorIPv4 / CIDR

Cross-checked

IPv4 address

Dotted-decimal, e.g. 192.168.10.130. Each octet 0–255.

Subnet mask

CIDR prefix/26

Try

Network address

192.168.10.128

Broadcast address

192.168.10.191

Usable hosts

64 total addresses

Usable host range

192.168.10.129 – 192.168.10.190

Full breakdown

Field	Value
CIDR notation	192.168.10.128/26
Subnet mask	255.255.255.192 (/26)
Wildcard mask	0.0.0.63
Address type	Private (RFC 1918)
IP class	Class C (192.0.0.0 – 223.255.255.255)
IP in binary	11000000.10101000.00001010.10000010
Mask in binary	11111111.11111111.11111111.11000000
IP as integer	3,232,238,210
Previous subnet	192.168.10.64/26
Next subnet	192.168.10.192/26

Split this block into equal subnets

Bit math follows RFC 4632 (CIDR). Address-type ranges from RFC 1918, 6598, 3927, 5737 and the IANA IPv4 Special-Purpose registry — all cited below. Runs entirely in your browser; nothing is sent to a server.

How it works

A subnet calculator works on the 32-bit integer behind every IPv4 address. The dotted-decimal form 192.168.10.130 is really four 8-bit octets packed into one 32-bit number. The CIDR prefix (the /26 part) says how many leading bits identify the network; the rest identify the host. This is the classless model defined in RFC 4632, which replaced the older fixed Class A/B/C boundaries.

Build the mask. A prefix of p sets the top p bits to 1: mask = 0xFFFFFFFF << (32 − p). For /26 that is 255.255.255.192.
Wildcard mask. Invert the mask: wildcard = NOT mask — 0.0.0.63 for a /26. Cisco ACLs and OSPF statements match on this.
Network address. network = IP AND mask. This zeroes the host bits, giving the first address in the block.
Broadcast address. broadcast = network OR wildcard — the last address, where every host bit is 1.
Host count. A block holds 2^(32 − p) addresses. For prefixes /30 and shorter, two are reserved (network + broadcast), so usable hosts = 2^(32 − p) − 2. A /31 (RFC 3021) makes both addresses usable for point-to-point links, and a /32 is a single host route.
Address type. The tool tests the address against the IANA special-purpose ranges using the same AND-with-mask containment test: private (RFC 1918: 10/8, 172.16/12, 192.168/16), loopback (127/8), CGNAT (RFC 6598: 100.64/10), link-local (RFC 3927: 169.254/16), documentation (RFC 5737), multicast and reserved. Anything else is public.

Every result is verified two ways: the network address is computed once on the full 32-bit integer (IP AND mask) and once by masking each octet independently. The two paths must agree, and the calculator shows a “Cross-checked” badge when they do. JavaScript treats bitwise operands as signed 32-bit values, so each step is normalised back to unsigned, and the /0 case (which would otherwise hit a <<32 no-op bug) is handled explicitly.

Worked examples

192.168.10.130 /26 — a host inside a block

Mask /26 = 255.255.255.192, wildcard = 0.0.0.63, block size = 2^6 = 64
130 in binary is 10000010; AND 11000000 (192) → 10000000 = 128
Network = 192.168.10.128, broadcast = 192.168.10.191
Usable range: 192.168.10.129 – 192.168.10.190
Total 64 addresses, usable 62 (64 − 2)
Class C, Private (RFC 1918, 192.168.0.0/16)

10.20.0.0 /22 — a multi-octet mask for a VPC

Mask /22 = 255.255.252.0, wildcard = 0.0.3.255, block size = 2^10 = 1024
The mask borrows 6 bits of the third octet (252), so blocks step by 4 there
Network = 10.20.0.0, broadcast = 10.20.3.255
Usable range: 10.20.0.1 – 10.20.3.254
Total 1,024 addresses, usable 1,022
Class A, Private (RFC 1918, 10.0.0.0/8)

172.16.45.14 /30 — a point-to-point link

Mask /30 = 255.255.255.252, wildcard = 0.0.0.3, block size = 4
14 (00001110) AND 252 (11111100) → 12 (00001100)
Network = 172.16.45.12, broadcast = 172.16.45.15
Usable range: 172.16.45.13 – 172.16.45.14 (just 2 hosts)
Class B, Private (RFC 1918, 172.16.0.0/12)

Frequently asked questions

Sources & references

The mask table and special-purpose ranges on this page were last cross-checked against the RFCs and the IANA registry on 2026-06-08. They are reviewed whenever IANA updates the special-purpose registry.

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