Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

Computers and devices

Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network83.4.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
83.4.64.0
Broadcast address
83.4.95.255
First usable
83.4.64.1
Last usable
83.4.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 53044000 · Integer 1392787456 to 1392795647
Reverse DNS zones
64.4.83.in-addr.arpa
65.4.83.in-addr.arpa
66.4.83.in-addr.arpa
67.4.83.in-addr.arpa
68.4.83.in-addr.arpa
69.4.83.in-addr.arpa
70.4.83.in-addr.arpa
71.4.83.in-addr.arpa
72.4.83.in-addr.arpa
73.4.83.in-addr.arpa
74.4.83.in-addr.arpa
75.4.83.in-addr.arpa
76.4.83.in-addr.arpa
77.4.83.in-addr.arpa
78.4.83.in-addr.arpa
79.4.83.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010011.00000100.01000000.0000000083.4.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network01010011.00000100.01000000.0000000083.4.64.0
Broadcast01010011.00000100.01011111.1111111183.4.95.255
Split into smaller subnets/29
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

83.4.64.0/19 makes 1,024 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
183.4.64.0/2983.4.64.1 to 83.4.64.683.4.64.76
283.4.64.8/2983.4.64.9 to 83.4.64.1483.4.64.156
383.4.64.16/2983.4.64.17 to 83.4.64.2283.4.64.236
483.4.64.24/2983.4.64.25 to 83.4.64.3083.4.64.316
583.4.64.32/2983.4.64.33 to 83.4.64.3883.4.64.396
683.4.64.40/2983.4.64.41 to 83.4.64.4683.4.64.476
783.4.64.48/2983.4.64.49 to 83.4.64.5483.4.64.556
883.4.64.56/2983.4.64.57 to 83.4.64.6283.4.64.636
983.4.64.64/2983.4.64.65 to 83.4.64.7083.4.64.716
1083.4.64.72/2983.4.64.73 to 83.4.64.7883.4.64.796
1183.4.64.80/2983.4.64.81 to 83.4.64.8683.4.64.876
1283.4.64.88/2983.4.64.89 to 83.4.64.9483.4.64.956
1383.4.64.96/2983.4.64.97 to 83.4.64.10283.4.64.1036
1483.4.64.104/2983.4.64.105 to 83.4.64.11083.4.64.1116
1583.4.64.112/2983.4.64.113 to 83.4.64.11883.4.64.1196
1683.4.64.120/2983.4.64.121 to 83.4.64.12683.4.64.1276
1783.4.64.128/2983.4.64.129 to 83.4.64.13483.4.64.1356
1883.4.64.136/2983.4.64.137 to 83.4.64.14283.4.64.1436
1983.4.64.144/2983.4.64.145 to 83.4.64.15083.4.64.1516
2083.4.64.152/2983.4.64.153 to 83.4.64.15883.4.64.1596
2183.4.64.160/2983.4.64.161 to 83.4.64.16683.4.64.1676
2283.4.64.168/2983.4.64.169 to 83.4.64.17483.4.64.1756
2383.4.64.176/2983.4.64.177 to 83.4.64.18283.4.64.1836
2483.4.64.184/2983.4.64.185 to 83.4.64.19083.4.64.1916
2583.4.64.192/2983.4.64.193 to 83.4.64.19883.4.64.1996
2683.4.64.200/2983.4.64.201 to 83.4.64.20683.4.64.2076
2783.4.64.208/2983.4.64.209 to 83.4.64.21483.4.64.2156
2883.4.64.216/2983.4.64.217 to 83.4.64.22283.4.64.2236
2983.4.64.224/2983.4.64.225 to 83.4.64.23083.4.64.2316
3083.4.64.232/2983.4.64.233 to 83.4.64.23883.4.64.2396
3183.4.64.240/2983.4.64.241 to 83.4.64.24683.4.64.2476
3283.4.64.248/2983.4.64.249 to 83.4.64.25483.4.64.2556
3383.4.65.0/2983.4.65.1 to 83.4.65.683.4.65.76
3483.4.65.8/2983.4.65.9 to 83.4.65.1483.4.65.156
3583.4.65.16/2983.4.65.17 to 83.4.65.2283.4.65.236
3683.4.65.24/2983.4.65.25 to 83.4.65.3083.4.65.316
3783.4.65.32/2983.4.65.33 to 83.4.65.3883.4.65.396
3883.4.65.40/2983.4.65.41 to 83.4.65.4683.4.65.476
3983.4.65.48/2983.4.65.49 to 83.4.65.5483.4.65.556
4083.4.65.56/2983.4.65.57 to 83.4.65.6283.4.65.636
4183.4.65.64/2983.4.65.65 to 83.4.65.7083.4.65.716
4283.4.65.72/2983.4.65.73 to 83.4.65.7883.4.65.796
4383.4.65.80/2983.4.65.81 to 83.4.65.8683.4.65.876
4483.4.65.88/2983.4.65.89 to 83.4.65.9483.4.65.956
4583.4.65.96/2983.4.65.97 to 83.4.65.10283.4.65.1036
4683.4.65.104/2983.4.65.105 to 83.4.65.11083.4.65.1116
4783.4.65.112/2983.4.65.113 to 83.4.65.11883.4.65.1196
4883.4.65.120/2983.4.65.121 to 83.4.65.12683.4.65.1276
4983.4.65.128/2983.4.65.129 to 83.4.65.13483.4.65.1356
5083.4.65.136/2983.4.65.137 to 83.4.65.14283.4.65.1436
5183.4.65.144/2983.4.65.145 to 83.4.65.15083.4.65.1516
5283.4.65.152/2983.4.65.153 to 83.4.65.15883.4.65.1596
5383.4.65.160/2983.4.65.161 to 83.4.65.16683.4.65.1676
5483.4.65.168/2983.4.65.169 to 83.4.65.17483.4.65.1756
5583.4.65.176/2983.4.65.177 to 83.4.65.18283.4.65.1836
5683.4.65.184/2983.4.65.185 to 83.4.65.19083.4.65.1916
5783.4.65.192/2983.4.65.193 to 83.4.65.19883.4.65.1996
5883.4.65.200/2983.4.65.201 to 83.4.65.20683.4.65.2076
5983.4.65.208/2983.4.65.209 to 83.4.65.21483.4.65.2156
6083.4.65.216/2983.4.65.217 to 83.4.65.22283.4.65.2236
6183.4.65.224/2983.4.65.225 to 83.4.65.23083.4.65.2316
6283.4.65.232/2983.4.65.233 to 83.4.65.23883.4.65.2396
6383.4.65.240/2983.4.65.241 to 83.4.65.24683.4.65.2476
6483.4.65.248/2983.4.65.249 to 83.4.65.25483.4.65.2556
6583.4.66.0/2983.4.66.1 to 83.4.66.683.4.66.76
6683.4.66.8/2983.4.66.9 to 83.4.66.1483.4.66.156
6783.4.66.16/2983.4.66.17 to 83.4.66.2283.4.66.236
6883.4.66.24/2983.4.66.25 to 83.4.66.3083.4.66.316
6983.4.66.32/2983.4.66.33 to 83.4.66.3883.4.66.396
7083.4.66.40/2983.4.66.41 to 83.4.66.4683.4.66.476
7183.4.66.48/2983.4.66.49 to 83.4.66.5483.4.66.556
7283.4.66.56/2983.4.66.57 to 83.4.66.6283.4.66.636
7383.4.66.64/2983.4.66.65 to 83.4.66.7083.4.66.716
7483.4.66.72/2983.4.66.73 to 83.4.66.7883.4.66.796
7583.4.66.80/2983.4.66.81 to 83.4.66.8683.4.66.876
7683.4.66.88/2983.4.66.89 to 83.4.66.9483.4.66.956
7783.4.66.96/2983.4.66.97 to 83.4.66.10283.4.66.1036
7883.4.66.104/2983.4.66.105 to 83.4.66.11083.4.66.1116
7983.4.66.112/2983.4.66.113 to 83.4.66.11883.4.66.1196
8083.4.66.120/2983.4.66.121 to 83.4.66.12683.4.66.1276
8183.4.66.128/2983.4.66.129 to 83.4.66.13483.4.66.1356
8283.4.66.136/2983.4.66.137 to 83.4.66.14283.4.66.1436
8383.4.66.144/2983.4.66.145 to 83.4.66.15083.4.66.1516
8483.4.66.152/2983.4.66.153 to 83.4.66.15883.4.66.1596
8583.4.66.160/2983.4.66.161 to 83.4.66.16683.4.66.1676
8683.4.66.168/2983.4.66.169 to 83.4.66.17483.4.66.1756
8783.4.66.176/2983.4.66.177 to 83.4.66.18283.4.66.1836
8883.4.66.184/2983.4.66.185 to 83.4.66.19083.4.66.1916
8983.4.66.192/2983.4.66.193 to 83.4.66.19883.4.66.1996
9083.4.66.200/2983.4.66.201 to 83.4.66.20683.4.66.2076
9183.4.66.208/2983.4.66.209 to 83.4.66.21483.4.66.2156
9283.4.66.216/2983.4.66.217 to 83.4.66.22283.4.66.2236
9383.4.66.224/2983.4.66.225 to 83.4.66.23083.4.66.2316
9483.4.66.232/2983.4.66.233 to 83.4.66.23883.4.66.2396
9583.4.66.240/2983.4.66.241 to 83.4.66.24683.4.66.2476
9683.4.66.248/2983.4.66.249 to 83.4.66.25483.4.66.2556
9783.4.67.0/2983.4.67.1 to 83.4.67.683.4.67.76
9883.4.67.8/2983.4.67.9 to 83.4.67.1483.4.67.156
9983.4.67.16/2983.4.67.17 to 83.4.67.2283.4.67.236
10083.4.67.24/2983.4.67.25 to 83.4.67.3083.4.67.316
10183.4.67.32/2983.4.67.33 to 83.4.67.3883.4.67.396
10283.4.67.40/2983.4.67.41 to 83.4.67.4683.4.67.476
10383.4.67.48/2983.4.67.49 to 83.4.67.5483.4.67.556
10483.4.67.56/2983.4.67.57 to 83.4.67.6283.4.67.636
10583.4.67.64/2983.4.67.65 to 83.4.67.7083.4.67.716
10683.4.67.72/2983.4.67.73 to 83.4.67.7883.4.67.796
10783.4.67.80/2983.4.67.81 to 83.4.67.8683.4.67.876
10883.4.67.88/2983.4.67.89 to 83.4.67.9483.4.67.956
10983.4.67.96/2983.4.67.97 to 83.4.67.10283.4.67.1036
11083.4.67.104/2983.4.67.105 to 83.4.67.11083.4.67.1116
11183.4.67.112/2983.4.67.113 to 83.4.67.11883.4.67.1196
11283.4.67.120/2983.4.67.121 to 83.4.67.12683.4.67.1276
11383.4.67.128/2983.4.67.129 to 83.4.67.13483.4.67.1356
11483.4.67.136/2983.4.67.137 to 83.4.67.14283.4.67.1436
11583.4.67.144/2983.4.67.145 to 83.4.67.15083.4.67.1516
11683.4.67.152/2983.4.67.153 to 83.4.67.15883.4.67.1596
11783.4.67.160/2983.4.67.161 to 83.4.67.16683.4.67.1676
11883.4.67.168/2983.4.67.169 to 83.4.67.17483.4.67.1756
11983.4.67.176/2983.4.67.177 to 83.4.67.18283.4.67.1836
12083.4.67.184/2983.4.67.185 to 83.4.67.19083.4.67.1916
12183.4.67.192/2983.4.67.193 to 83.4.67.19883.4.67.1996
12283.4.67.200/2983.4.67.201 to 83.4.67.20683.4.67.2076
12383.4.67.208/2983.4.67.209 to 83.4.67.21483.4.67.2156
12483.4.67.216/2983.4.67.217 to 83.4.67.22283.4.67.2236
12583.4.67.224/2983.4.67.225 to 83.4.67.23083.4.67.2316
12683.4.67.232/2983.4.67.233 to 83.4.67.23883.4.67.2396
12783.4.67.240/2983.4.67.241 to 83.4.67.24683.4.67.2476
12883.4.67.248/2983.4.67.249 to 83.4.67.25483.4.67.2556
12983.4.68.0/2983.4.68.1 to 83.4.68.683.4.68.76
13083.4.68.8/2983.4.68.9 to 83.4.68.1483.4.68.156
13183.4.68.16/2983.4.68.17 to 83.4.68.2283.4.68.236
13283.4.68.24/2983.4.68.25 to 83.4.68.3083.4.68.316
13383.4.68.32/2983.4.68.33 to 83.4.68.3883.4.68.396
13483.4.68.40/2983.4.68.41 to 83.4.68.4683.4.68.476
13583.4.68.48/2983.4.68.49 to 83.4.68.5483.4.68.556
13683.4.68.56/2983.4.68.57 to 83.4.68.6283.4.68.636
13783.4.68.64/2983.4.68.65 to 83.4.68.7083.4.68.716
13883.4.68.72/2983.4.68.73 to 83.4.68.7883.4.68.796
13983.4.68.80/2983.4.68.81 to 83.4.68.8683.4.68.876
14083.4.68.88/2983.4.68.89 to 83.4.68.9483.4.68.956
14183.4.68.96/2983.4.68.97 to 83.4.68.10283.4.68.1036
14283.4.68.104/2983.4.68.105 to 83.4.68.11083.4.68.1116
14383.4.68.112/2983.4.68.113 to 83.4.68.11883.4.68.1196
14483.4.68.120/2983.4.68.121 to 83.4.68.12683.4.68.1276
14583.4.68.128/2983.4.68.129 to 83.4.68.13483.4.68.1356
14683.4.68.136/2983.4.68.137 to 83.4.68.14283.4.68.1436
14783.4.68.144/2983.4.68.145 to 83.4.68.15083.4.68.1516
14883.4.68.152/2983.4.68.153 to 83.4.68.15883.4.68.1596
14983.4.68.160/2983.4.68.161 to 83.4.68.16683.4.68.1676
15083.4.68.168/2983.4.68.169 to 83.4.68.17483.4.68.1756
15183.4.68.176/2983.4.68.177 to 83.4.68.18283.4.68.1836
15283.4.68.184/2983.4.68.185 to 83.4.68.19083.4.68.1916
15383.4.68.192/2983.4.68.193 to 83.4.68.19883.4.68.1996
15483.4.68.200/2983.4.68.201 to 83.4.68.20683.4.68.2076
15583.4.68.208/2983.4.68.209 to 83.4.68.21483.4.68.2156
15683.4.68.216/2983.4.68.217 to 83.4.68.22283.4.68.2236
15783.4.68.224/2983.4.68.225 to 83.4.68.23083.4.68.2316
15883.4.68.232/2983.4.68.233 to 83.4.68.23883.4.68.2396
15983.4.68.240/2983.4.68.241 to 83.4.68.24683.4.68.2476
16083.4.68.248/2983.4.68.249 to 83.4.68.25483.4.68.2556
16183.4.69.0/2983.4.69.1 to 83.4.69.683.4.69.76
16283.4.69.8/2983.4.69.9 to 83.4.69.1483.4.69.156
16383.4.69.16/2983.4.69.17 to 83.4.69.2283.4.69.236
16483.4.69.24/2983.4.69.25 to 83.4.69.3083.4.69.316
16583.4.69.32/2983.4.69.33 to 83.4.69.3883.4.69.396
16683.4.69.40/2983.4.69.41 to 83.4.69.4683.4.69.476
16783.4.69.48/2983.4.69.49 to 83.4.69.5483.4.69.556
16883.4.69.56/2983.4.69.57 to 83.4.69.6283.4.69.636
16983.4.69.64/2983.4.69.65 to 83.4.69.7083.4.69.716
17083.4.69.72/2983.4.69.73 to 83.4.69.7883.4.69.796
17183.4.69.80/2983.4.69.81 to 83.4.69.8683.4.69.876
17283.4.69.88/2983.4.69.89 to 83.4.69.9483.4.69.956
17383.4.69.96/2983.4.69.97 to 83.4.69.10283.4.69.1036
17483.4.69.104/2983.4.69.105 to 83.4.69.11083.4.69.1116
17583.4.69.112/2983.4.69.113 to 83.4.69.11883.4.69.1196
17683.4.69.120/2983.4.69.121 to 83.4.69.12683.4.69.1276
17783.4.69.128/2983.4.69.129 to 83.4.69.13483.4.69.1356
17883.4.69.136/2983.4.69.137 to 83.4.69.14283.4.69.1436
17983.4.69.144/2983.4.69.145 to 83.4.69.15083.4.69.1516
18083.4.69.152/2983.4.69.153 to 83.4.69.15883.4.69.1596
18183.4.69.160/2983.4.69.161 to 83.4.69.16683.4.69.1676
18283.4.69.168/2983.4.69.169 to 83.4.69.17483.4.69.1756
18383.4.69.176/2983.4.69.177 to 83.4.69.18283.4.69.1836
18483.4.69.184/2983.4.69.185 to 83.4.69.19083.4.69.1916
18583.4.69.192/2983.4.69.193 to 83.4.69.19883.4.69.1996
18683.4.69.200/2983.4.69.201 to 83.4.69.20683.4.69.2076
18783.4.69.208/2983.4.69.209 to 83.4.69.21483.4.69.2156
18883.4.69.216/2983.4.69.217 to 83.4.69.22283.4.69.2236
18983.4.69.224/2983.4.69.225 to 83.4.69.23083.4.69.2316
19083.4.69.232/2983.4.69.233 to 83.4.69.23883.4.69.2396
19183.4.69.240/2983.4.69.241 to 83.4.69.24683.4.69.2476
19283.4.69.248/2983.4.69.249 to 83.4.69.25483.4.69.2556
19383.4.70.0/2983.4.70.1 to 83.4.70.683.4.70.76
19483.4.70.8/2983.4.70.9 to 83.4.70.1483.4.70.156
19583.4.70.16/2983.4.70.17 to 83.4.70.2283.4.70.236
19683.4.70.24/2983.4.70.25 to 83.4.70.3083.4.70.316
19783.4.70.32/2983.4.70.33 to 83.4.70.3883.4.70.396
19883.4.70.40/2983.4.70.41 to 83.4.70.4683.4.70.476
19983.4.70.48/2983.4.70.49 to 83.4.70.5483.4.70.556
20083.4.70.56/2983.4.70.57 to 83.4.70.6283.4.70.636
20183.4.70.64/2983.4.70.65 to 83.4.70.7083.4.70.716
20283.4.70.72/2983.4.70.73 to 83.4.70.7883.4.70.796
20383.4.70.80/2983.4.70.81 to 83.4.70.8683.4.70.876
20483.4.70.88/2983.4.70.89 to 83.4.70.9483.4.70.956
20583.4.70.96/2983.4.70.97 to 83.4.70.10283.4.70.1036
20683.4.70.104/2983.4.70.105 to 83.4.70.11083.4.70.1116
20783.4.70.112/2983.4.70.113 to 83.4.70.11883.4.70.1196
20883.4.70.120/2983.4.70.121 to 83.4.70.12683.4.70.1276
20983.4.70.128/2983.4.70.129 to 83.4.70.13483.4.70.1356
21083.4.70.136/2983.4.70.137 to 83.4.70.14283.4.70.1436
21183.4.70.144/2983.4.70.145 to 83.4.70.15083.4.70.1516
21283.4.70.152/2983.4.70.153 to 83.4.70.15883.4.70.1596
21383.4.70.160/2983.4.70.161 to 83.4.70.16683.4.70.1676
21483.4.70.168/2983.4.70.169 to 83.4.70.17483.4.70.1756
21583.4.70.176/2983.4.70.177 to 83.4.70.18283.4.70.1836
21683.4.70.184/2983.4.70.185 to 83.4.70.19083.4.70.1916
21783.4.70.192/2983.4.70.193 to 83.4.70.19883.4.70.1996
21883.4.70.200/2983.4.70.201 to 83.4.70.20683.4.70.2076
21983.4.70.208/2983.4.70.209 to 83.4.70.21483.4.70.2156
22083.4.70.216/2983.4.70.217 to 83.4.70.22283.4.70.2236
22183.4.70.224/2983.4.70.225 to 83.4.70.23083.4.70.2316
22283.4.70.232/2983.4.70.233 to 83.4.70.23883.4.70.2396
22383.4.70.240/2983.4.70.241 to 83.4.70.24683.4.70.2476
22483.4.70.248/2983.4.70.249 to 83.4.70.25483.4.70.2556
22583.4.71.0/2983.4.71.1 to 83.4.71.683.4.71.76
22683.4.71.8/2983.4.71.9 to 83.4.71.1483.4.71.156
22783.4.71.16/2983.4.71.17 to 83.4.71.2283.4.71.236
22883.4.71.24/2983.4.71.25 to 83.4.71.3083.4.71.316
22983.4.71.32/2983.4.71.33 to 83.4.71.3883.4.71.396
23083.4.71.40/2983.4.71.41 to 83.4.71.4683.4.71.476
23183.4.71.48/2983.4.71.49 to 83.4.71.5483.4.71.556
23283.4.71.56/2983.4.71.57 to 83.4.71.6283.4.71.636
23383.4.71.64/2983.4.71.65 to 83.4.71.7083.4.71.716
23483.4.71.72/2983.4.71.73 to 83.4.71.7883.4.71.796
23583.4.71.80/2983.4.71.81 to 83.4.71.8683.4.71.876
23683.4.71.88/2983.4.71.89 to 83.4.71.9483.4.71.956
23783.4.71.96/2983.4.71.97 to 83.4.71.10283.4.71.1036
23883.4.71.104/2983.4.71.105 to 83.4.71.11083.4.71.1116
23983.4.71.112/2983.4.71.113 to 83.4.71.11883.4.71.1196
24083.4.71.120/2983.4.71.121 to 83.4.71.12683.4.71.1276
24183.4.71.128/2983.4.71.129 to 83.4.71.13483.4.71.1356
24283.4.71.136/2983.4.71.137 to 83.4.71.14283.4.71.1436
24383.4.71.144/2983.4.71.145 to 83.4.71.15083.4.71.1516
24483.4.71.152/2983.4.71.153 to 83.4.71.15883.4.71.1596
24583.4.71.160/2983.4.71.161 to 83.4.71.16683.4.71.1676
24683.4.71.168/2983.4.71.169 to 83.4.71.17483.4.71.1756
24783.4.71.176/2983.4.71.177 to 83.4.71.18283.4.71.1836
24883.4.71.184/2983.4.71.185 to 83.4.71.19083.4.71.1916
24983.4.71.192/2983.4.71.193 to 83.4.71.19883.4.71.1996
25083.4.71.200/2983.4.71.201 to 83.4.71.20683.4.71.2076
25183.4.71.208/2983.4.71.209 to 83.4.71.21483.4.71.2156
25283.4.71.216/2983.4.71.217 to 83.4.71.22283.4.71.2236
25383.4.71.224/2983.4.71.225 to 83.4.71.23083.4.71.2316
25483.4.71.232/2983.4.71.233 to 83.4.71.23883.4.71.2396
25583.4.71.240/2983.4.71.241 to 83.4.71.24683.4.71.2476
25683.4.71.248/2983.4.71.249 to 83.4.71.25483.4.71.2556

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.