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Subnet Mask Calculator.

Convert between CIDR prefix, subnet mask and wildcard mask, find the smallest mask for a number of hosts, and browse the full /0–/32 table.

Limits & supported formats

IPv4 only. Non-contiguous masks are rejected. 0.0.0.0 and 255.255.255.255 are read as subnet masks. Everything is calculated in your browser; nothing is sent or probed on the network.

CALCULATED IN YOUR BROWSER · NOTHING IS UPLOADED
Prefix/26255.255.255.192
Subnet mask
255.255.255.192
Wildcard mask
0.0.0.63
CIDR prefix
/26
Mask in hexadecimal
0xFFFFFFC0
Mask in binary
11111111.11111111.11111111.11000000
Total addresses
64
Usable hosts
62
Total minus network and broadcast
Subnets of this size in a /24
4

IPv4 subnet mask reference

PrefixSubnet maskWildcardAddressesUsable hosts
/00.0.0.0255.255.255.2554,294,967,2964,294,967,294
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,646
/2192.0.0.063.255.255.2551,073,741,8241,073,741,822
/3224.0.0.031.255.255.255536,870,912536,870,910
/4240.0.0.015.255.255.255268,435,456268,435,454
/5248.0.0.07.255.255.255134,217,728134,217,726
/6252.0.0.03.255.255.25567,108,86467,108,862
/7254.0.0.01.255.255.25533,554,43233,554,430
/8255.0.0.00.255.255.25516,777,21616,777,214
/9255.128.0.00.127.255.2558,388,6088,388,606
/10255.192.0.00.63.255.2554,194,3044,194,302
/11255.224.0.00.31.255.2552,097,1522,097,150
/12255.240.0.00.15.255.2551,048,5761,048,574
/13255.248.0.00.7.255.255524,288524,286
/14255.252.0.00.3.255.255262,144262,142
/15255.254.0.00.1.255.255131,072131,070
/16255.255.0.00.0.255.25565,53665,534
/17255.255.128.00.0.127.25532,76832,766
/18255.255.192.00.0.63.25516,38416,382
/19255.255.224.00.0.31.2558,1928,190
/20255.255.240.00.0.15.2554,0964,094
/21255.255.248.00.0.7.2552,0482,046
/22255.255.252.00.0.3.2551,0241,022
/23255.255.254.00.0.1.255512510
/24255.255.255.00.0.0.255256254
/25255.255.255.1280.0.0.127128126
/26255.255.255.1920.0.0.636462
/27255.255.255.2240.0.0.313230
/28255.255.255.2400.0.0.151614
/29255.255.255.2480.0.0.786
/30255.255.255.2520.0.0.342
/31255.255.255.2540.0.0.122 (RFC 3021)
/32255.255.255.2550.0.0.011
  • Read as a subnet mask.
  • Cisco ACLs and OSPF network statements use the wildcard mask.

How to use Subnet Mask Calculator

Type a prefix (/26), a subnet mask or a wildcard mask, or switch to “Number of hosts needed”. The reference table highlights the matching row.

How it works

A subnet mask is a run of 1 bits followed by 0 bits; the wildcard mask is its bitwise inverse, used by Cisco ACLs and OSPF. Usable hosts are 2^(32 − prefix) − 2, except /31 and /32.

Example

255.255.255.192 is /26 with wildcard 0.0.0.63 and 62 usable hosts; 50 hosts need at least a /26.

Questions about Subnet Mask Calculator

Is Subnet Mask Calculator free, and do I need an account?

Yes. This tool is free to use in your browser without an account. Processing takes place on your device.

What are the limits and what should I check?

IPv4 only. Non-contiguous masks are rejected. 0.0.0.0 and 255.255.255.255 are read as subnet masks. Everything is calculated in your browser; nothing is sent or probed on the network. Review the result before using it in your work.

Is my input sent to a server?

Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.