IPv4 Subnet Cheat Sheet

IPv4 Subnet Cheat Sheet

My Calculator

CIDR	Subnet Mask	Total IPs	Usable IPs
/32	255.255.255.255	1	1
/31	255.255.255.254	2	2*
/30	255.255.255.252	4	2
/29	255.255.255.248	8	6
/28	255.255.255.240	16	14
/27	255.255.255.224	32	30
/26	255.255.255.192	64	62
/25	255.255.255.128	128	126
/24	255.255.255.0	256	254
/23	255.255.254.0	512	510
/22	255.255.252.0	1024	1022
/21	255.255.248.0	2048	2046
/20	255.255.240.0	4096	4094
/19	255.255.224.0	8192	8190
/18	255.255.192.0	16,384	16,382
/17	255.255.128.0	32,768	32,766
/16	255.255.0.0	65,536	65,534
/15	255.254.0.0	131,072	131,070
/14	255.252.0.0	262,144	262,142
/13	255.248.0.0	524,288	524,286
/12	255.240.0.0	1,048,576	1,048,574
/11	255.224.0.0	2,097,152	2,097,150
/10	255.192.0.0	4,194,304	4,194,302
/9	255.128.0.0	8,388,608	8,388,606
/8	255.0.0.0	16,777,216	16,777,214
/7	254.0.0.0	33,554,432	33,554,430
/6	252.0.0.0	67,108,864	67,108,862
/5	248.0.0.0	134,217,728	134,217,726
/4	240.0.0.0	268,435,456	268,435,454
/3	224.0.0.0	536,870,912	536,870,910
/2	192.0.0.0	1,073,741,824	1,073,741,822
/1	128.0.0.0	2,147,483,648	2,147,483,646

*See rfc 3021

Private IP ranges

Class	Size	Subnet Mask	Range of IPs
Class A	10.0.0.0/8	255.0.0.0	10.0.0.0 – 10.255.255.255
Class B	172.16.0.0/12	255.240.0.0	172.16.0.0 – 172.31.255.255
Class C	192.168.0.0/16	255.255.0.0	192.168.0.0 – 192.168.255.255

IPv6

Prefix	/48s	/56s	/64s
/24	16M	4G	1T
/25	8M	2G	512G
/26	4M	1G	256G
/27	2M	512M	128G
/28	1M	256M	64G
/29	512K	128M	32G
/30	256K	64M	16G
/31	128K	32M	8G
/32	64K	16M	4G
/33	32K	8M	2G
/34	16K	4M	1G
/35	8K	2M	512M
/36	4K	1M	256M
/37	2K	512K	128M
/38	1K	256K	64M
/39	512	128K	32M
/40	256	64K	16M
/41	128	32K	8M
/42	64	16K	4M
/43	32	8K	2M
/44	16	4K	1M
/45	8	2K	512K
/46	4	1K	256K
/47	2	512	128K
/48	1	256	64K
/49		128	32K
/50		64	16K
/51		32	8K
/52		16	4K
/53		8	2K
/54		4	1K
/55		2	512
/56		1	256
/57			128
/58			64
/59			32
/60			16
/61			8
/62			4
/63			2
/64			1

IPv6 bit mapping

Binary

Bit	1	1	1	1	1	1	1	1
Bit Value	128	64	32	16	8	4	2	1

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