CIDR Subnet Mask Cheat Sheet

We know it can be pain trying to remember which CIDR notation to use or what subnet mask to enter for a specific subnet. That’s why we created this awesome looking IPv4 CIDR cheat sheet for you to use.

Feel free to print it out and hang it up or share a link to it with your colleagues and peers.

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Free CIDR Subnet Mask Cheat Sheet

Free cheat sheet for IPv4 CIDR notation and subnet masks.

Click on the subnet mask chart to view the printable, searchable PDF version. Scroll down below for the CIDR subnet mask tables.

Related: Common Ports Cheat Sheet

IPv4 Subnets

An IPv4 subnet is a division of the IPv4 address space used to create smaller, interconnected networks within a larger network. It involves dividing the available IP addresses into subnetworks or subnets, each with its own unique range of addresses.

Subnetting allows for efficient allocation of IP addresses, improves network scalability and management, and enables logical segmentation of networks. Subnets are defined by combining an IP address with a subnet mask, which determines the network and host portions of the address.

CIDR	SUBNET MASK	ADDRESSES	WILDCARD
/0	0.0.0.0	4294967296	255.255.255.255
/1	128.0.0.0	2147483648	127.255.255.255
/2	192.0.0.0	1073741824	63.255.255.255
/3	224.0.0.0	536870912	31.255.255.255
/4	240.0.0.0	268435456	15.255.255.255
/5	248.0.0.0	134217728	7.255.255.255
/6	252.0.0.0	67108864	3.255.255.255
/7	254.0.0.0	33554432	1.255.255.255
/8	255.0.0.0	16777216	0.255.255.255
/9	255.128.0.0	8388608	0.127.255.255
/10	255.192.0.0	4194304	0.63.255.255
/11	255.224.0.0	2097152	0.31.255.255
/12	255.240.0.0	1048576	0.15.255.255
/13	255.248.0.0	524288	0.7.255.255
/14	255.252.0.0	262144	0.3.255.255
/15	255.254.0.0	131072	0.1.255.255
/16	255.255.0.0	65536	0.0.255.255
/17	255.255.128.0	32768	0.0.127.255
/18	255.255.192.0	16384	0.0.63.255
/19	255.255.224.0	8192	0.0.31.255
/20	255.255.240.0	4096	0.0.15.255
/21	255.255.248.0	2048	0.0.7.255
/22	255.255.252.0	1024	0.0.3.255
/23	255.255.254.0	512	0.0.1.255
/24	255.255.255.0	256	0.0.0.255
/25	255.255.255.128	128	0.0.0.127
/26	255.255.255.192	64	0.0.0.63
/27	255.255.255.224	32	0.0.0.31
/28	255.255.255.240	16	0.0.0.15
/29	255.255.255.248	8	0.0.0.7
/30	255.255.255.252	4	0.0.0.3
/31	255.255.255.254	2	0.0.0.1
/32	255.255.255.255	1	0.0.0.0

Classful Ranges

A classful range refers to a predefined range of IP addresses based on the original classful addressing scheme. The classful addressing scheme divides the IPv4 address space into five classes: A, B, C, D, and E. Each class has a specific range of IP addresses and a default mask associated with it. Classful ranges are characterized by fixed network and host portions based on the class with Class A having the largest network portion and Class C having the smallest.

Classful addressing has been largely replaced by classless inter-domain routing (CIDR), which allows for more flexible allocation of IP addresses by using variable-length subnet masks (VLSM).

Class Name	IP Range
Class A	0.0.0.0 – 127.255.255.255
Class B	128.0.0.0 – 191.255.255.255
Class C	192.0.0.0 – 223.255.255.255
Class D	224.0.0.0 – 239.255.255.255
Class E	240.0.0.0 – 254.255.255.254

Reserved Ranges

Reserved ranges are specific blocks of IP addresses that are designated for special purposes and are not available for general allocation or public use. These reserved ranges include private IP address ranges, loopback addresses, link-local addresses, and multicast addresses.

Range Name	IP Range
RFC 1918	10.0.0.0 – 10.255.255.255
Localhost	127.0.0.0 – 127.255.255.255
APIPA/BONJOUR	169.254.0.0 – 169.254.255.255
RFC 1918	172.16.0.0 – 172.31.255.255
RFC 1918	192.168.0.0 – 192.168.255.255

Bogon IPv4 Addresses and Ranges

Bogon addresses are IP addresses or address blocks that are invalid, unallocated, or not globally routable. Bogon addresses include IP addresses that should not appear on the internet and are commonly used in spoofing or malicious activities. These addresses may include reserved IP ranges, multicast addresses, or addresses that have not been assigned by the Internet Assigned Numbers Authority (IANA) or regional Internet registries.

Netblock	Description
0.0.0.0/8	“This” network
10.0.0.0/8	Private-use networks
100.64.0.0/10	Carrier-grade NAT
127.0.0.0/8	Loopback
127.0.53.53	Name collision occurrence
169.254.0.0/16	Link local
172.16.0.0/12	Private-use networks
192.0.0.0/24	IETF protocol assignments
192.0.2.0/24	TEST-NET-1
192.168.0.0/16	Private-use networks
198.18.0.0/15	Network interconnect device benchmark testing
198.51.100.0/24	TEST-NET-2
203.0.113.0/24	TEST-NET-3
224.0.0.0/4	Multicast
240.0.0.0/4	Reserved for future use
255.255.255.255/32	Limited broadcast

Decimal to Binary Table

Converting IPv4 addresses from decimal to binary may seem like a geeky task, but it has practical benefits in networking. By doing the conversion, you gain a deeper understanding of how IP addresses are structured. It helps with subnetting, routing, troubleshooting, and security. You can identify the network and host portions, determine subnet masks, pinpoint misconfigurations, analyze network traffic, and set up precise filtering.

Dec	Binary	Dec	Binary	Dec	Binary	Dec	Binary
0	0	64	1000000	128	10000000	192	11000000
1	1	65	1000001	129	10000001	193	11000001
2	10	66	1000010	130	10000010	194	11000010
3	11	67	1000011	131	10000011	195	11000011
4	100	68	1000100	132	10000100	196	11000100
5	101	69	1000101	133	10000101	197	11000101
6	110	70	1000110	134	10000110	198	11000110
7	111	71	1000111	135	10000111	199	11000111
8	1000	72	1001000	136	10001000	200	11001000
9	1001	73	1001001	137	10001001	201	11001001
10	1010	74	1001010	138	10001010	202	11001010
11	1011	75	1001011	139	10001011	203	11001011
12	1100	76	1001100	140	10001100	204	11001100
13	1101	77	1001101	141	10001101	205	11001101
14	1110	78	1001110	142	10001110	206	11001110
15	1111	79	1001111	143	10001111	207	11001111
16	10000	80	1010000	144	10010000	208	11010000
17	10001	81	1010001	145	10010001	209	11010001
18	10010	82	1010010	146	10010010	210	11010010
19	10011	83	1010011	147	10010011	211	11010011
20	10100	84	1010100	148	10010100	212	11010100
21	10101	85	1010101	149	10010101	213	11010101
22	10110	86	1010110	150	10010110	214	11010110
23	10111	87	1010111	151	10010111	215	11010111
24	11000	88	1011000	152	10011000	216	11011000
25	11001	89	1011001	153	10011001	217	11011001
26	11010	90	1011010	154	10011010	218	11011010
27	11011	91	1011011	155	10011011	219	11011011
28	11100	92	1011100	156	10011100	220	11011100
29	11101	93	1011101	157	10011101	221	11011101
30	11110	94	1011110	158	10011110	222	11011110
31	11111	95	1011111	159	10011111	223	11011111
32	100000	96	1100000	160	10100000	224	11100000
33	100001	97	1100001	161	10100001	225	11100001
34	100010	98	1100010	162	10100010	226	11100010
35	100011	99	1100011	163	10100011	227	11100011
36	100100	100	1100100	164	10100100	228	11100100
37	100101	101	1100101	165	10100101	229	11100101
38	100110	102	1100110	166	10100110	230	11100110
39	100111	103	1100111	167	10100111	231	11100111
40	101000	104	1101000	168	10101000	232	11101000
41	101001	105	1101001	169	10101001	233	11101001
42	101010	106	1101010	170	10101010	234	11101010
43	101011	107	1101011	171	10101011	235	11101011
44	101100	108	1101100	172	10101100	236	11101100
45	101101	109	1101101	173	10101101	237	11101101
46	101110	110	1101110	174	10101110	238	11101110
47	101111	111	1101111	175	10101111	239	11101111
48	110000	112	1110000	176	10110000	240	11110000
49	110001	113	1110001	177	10110001	241	11110001
50	110010	114	1110010	178	10110010	242	11110010
51	110011	115	1110011	179	10110011	243	11110011
52	110100	116	1110100	180	10110100	244	11110100
53	110101	117	1110101	181	10110101	245	11110101
54	110110	118	1110110	182	10110110	246	11110110
55	110111	119	1110111	183	10110111	247	11110111
56	111000	120	1111000	184	10111000	248	11111000
57	111001	121	1111001	185	10111001	249	11111001
58	111010	122	1111010	186	10111010	250	11111010
59	111011	123	1111011	187	10111011	251	11111011
60	111100	124	1111100	188	10111100	252	11111100
61	111101	125	1111101	189	10111101	253	11111101
62	111110	126	1111110	190	10111110	254	11111110
63	111111	127	1111111	191	10111111	255	11111111

Sub-Class C Blocks

A sub-class C block is a range of IP addresses that fall within the Class C address space. Class C addresses are identified by having the first three bits of the first octet set to “110,” which means the first octet ranges from 192 to 223. Each Class C network provides up to 256 addresses, with 254 available for host assignments. A sub-class C block is a subset of this address space, typically denoted by a specific network prefix length (CIDR notation) that allows for further subdivision and allocation of IP addresses within a Class C network.

/25 — 2 Subnets — 126 Hosts/Subnet

Network #	IP Range	Broadcast
0	.1-.126	0.127
0.128	.129-.254	0.255

/26 — 4 Subnets — 62 Hosts/Subnet

Network #	IP Range	Broadcast
0	.1-.62	0.63
0.64	.65-.126	0.127
0.128	.129-.190	0.191
0.192	.193-.254	0.255

/27 — 8 Subnets — 30 Hosts/Subnet

Network #	IP Range	Broadcast
0	.1-.30	0.31
0.32	.33-.62	0.63
0.64	.65-.94	0.95
0.96	.97-.126	0.127
0.128	.129-.158	0.159
0.16	.161-.190	0.191
0.192	.193-.222	0.223
0.224	.225-.254	0.255

/28 — 16 Subnets — 14 Hosts/Subnet

Network #	IP Range	Broadcast
0	.1-.14	0.15
0.16	.17-.30	0.31
0.32	.33-.46	0.47
0.48	.49-.62	0.63
0.64	.65-.78	0.79
0.8	.81-.94	0.95
0.96	.97-.110	0.111
0.112	.113-.126	0.127
0.128	.129-.142	0.143
0.144	.145-.158	0.159
0.16	.161-.174	0.175
0.176	.177-.190	0.191
0.192	.193-.206	0.207
0.208	.209-.222	0.223
0.224	.225-.238	0.239
0.24	.241-.254	0.255

/29 — 32 Subnets — 6 Hosts/Subnet

Network #	IP Range	Broadcast
0	.1-.6	0.7
0.8	.9-.14	0.15
0.16	.17-.22	0.23
0.24	.25-.30	0.31
0.32	.33-.38	0.39
0.4	.41-.46	0.47
0.48	.49-.54	0.55
0.56	.57-.62	0.63
0.64	.65-.70	0.71
0.72	.73-.78	0.79
0.8	.81-.86	0.87
0.88	.89-.94	0.95
0.96	.97-.102	0.103
0.104	.105-.110	0.111
0.112	.113-.118	0.119
0.12	.121-.126	0.127
0.128	.129-.134	0.135
0.136	.137-.142	0.143
0.144	.145-.150	0.151
0.152	.153-.158	0.159
0.16	.161-.166	0.167
0.168	.169-.174	0.175
0.176	.177-.182	0.183
0.184	.185-.190	0.191
0.192	.193-.198	0.199
0.2	.201-.206	0.207
0.208	.209-.214	0.215
0.216	.217-.222	0.223
0.224	.225-.230	0.231
0.232	.233-.238	0.239
0.24	.241-.246	0.247
0.248	.249-.254	0.255

/30 — 64 Subnets — 2 Hosts/Subnet

Network #	IP Range	Broadcast
0	.1-.2	0.3
0.4	.5-.6	0.7
0.8	.9-.10	0.11
0.12	.13-.14	0.15
0.16	.17-.18	0.19
0.2	.21-.22	0.23
0.24	.25-.26	0.27
0.28	.29-.30	0.31
0.32	.33-.34	0.35
0.36	.37-.38	0.39
0.4	.41-.42	0.43
0.44	.45-.46	0.47
0.48	.49-.50	0.51
0.52	.53-.54	0.55
0.56	.57-.58	0.59
0.6	.61-.62	0.63
0.64	.65-.66	0.67
0.68	.69-.70	0.71
0.72	.73-.74	0.75
0.76	.77-.78	0.79
0.8	.81-.82	0.83
0.84	.85-.86	0.87
0.88	.89-.90	0.91
0.92	.93-.94	0.95
0.96	.97-.98	0.99
0.1	.101-.102	0.103
0.104	.105-.106	0.107
0.108	.109-.110	0.111
0.112	.113-.114	0.115
0.116	.117-.118	0.119
0.12	.121-.122	0.123
0.124	.125-.126	0.127
0.128	.129-.130	0.131
0.132	.133-.134	0.135
0.136	.137-.138	0.139
0.14	.141-.142	0.143
0.144	.145-.146	0.147
0.148	.149-.150	0.151
0.152	.153-.154	0.155
0.156	.157-.158	0.159
0.16	.161-.162	0.163
0.164	.165-.166	0.167
0.168	.169-.170	0.171
0.172	.173-.174	0.175
0.176	.177-.178	0.179
0.18	.181-.182	0.183
0.184	.185-.186	0.187
0.188	.189-.190	0.191
0.192	.193-.194	0.195
0.196	.197-.198	0.199
0.2	.201-.202	0.203
0.204	.205-.206	0.207
0.208	.209-.210	0.211
0.212	.213-.214	0.215
0.216	.217-.218	0.219
0.22	.221-.222	0.223
0.224	.225-.226	0.227
0.228	.229-.230	0.231
0.232	.233-.234	0.235
0.236	.237-.238	0.239
0.24	.241-.242	0.243
0.244	.245-.246	0.247
0.248	.249-.250	0.251
0.252	.253-.254	0.255

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