Private IPv4 address ranges (RFC 1918)

Answer

RFC 1918 reserves three IPv4 ranges for private networks: 10.0.0.0/8 (10.0.0.0 to 10.255.255.255), 172.16.0.0/12 (172.16.0.0 to 172.31.255.255) and 192.168.0.0/16 (192.168.0.0 to 192.168.255.255). They are not routed on the public internet; devices using them reach the internet through NAT.

10.0.0.0/8 is 16,777,216 addresses: 10.0.0.0 to 10.255.255.255. 16,777,214 usable for hosts (the first is the network address, the last is broadcast).

1000001010000000000000000000000000000

8 network bits 24 host bits

Network: 10.0.0.0
First usable: 10.0.0.1
Last usable: 10.255.255.254
Broadcast: 10.255.255.255
Addresses: 16,777,216
Usable hosts: 16,777,214
Netmask: 255.0.0.0
Wildcard (ACL) mask: 0.255.255.255
Historic class: A
Range type: Private network · not routed on the internet

Special-purpose range

Private network 10.0.0.0/8 RFC 1918
The largest of the three private IPv4 ranges: 16.7 million addresses for use inside homes and organisations. Not routed on the public internet.

Every special-purpose IPv4 range

Block	What it is	Routable	RFC
`0.0.0.0/8`	This network	no	RFC 791
`10.0.0.0/8`	Private network	no	RFC 1918
`100.64.0.0/10`	Shared address space (carrier-grade NAT)	no	RFC 6598
`127.0.0.0/8`	Loopback	no	RFC 1122
`169.254.0.0/16`	Link-local	no	RFC 3927
`172.16.0.0/12`	Private network	no	RFC 1918
`192.0.0.0/24`	IETF protocol assignments	no	RFC 6890
`192.0.2.0/24`	Documentation (TEST-NET-1)	no	RFC 5737
`192.31.196.0/24`	AS112-v4	yes	RFC 7535
`192.52.193.0/24`	AMT	yes	RFC 7450
`192.88.99.0/24`	Deprecated 6to4 relay anycast	n/a	RFC 7526
`192.168.0.0/16`	Private network	no	RFC 1918
`192.175.48.0/24`	Direct delegation AS112 service	yes	RFC 7534
`198.18.0.0/15`	Benchmarking	no	RFC 2544
`198.51.100.0/24`	Documentation (TEST-NET-2)	no	RFC 5737
`203.0.113.0/24`	Documentation (TEST-NET-3)	no	RFC 5737
`224.0.0.0/4`	Multicast	n/a	RFC 5771
`240.0.0.0/4`	Reserved for future use	no	RFC 1112
`255.255.255.255/32`	Limited broadcast	no	RFC 919

Split it into subnets

4 subnets.

Subnet	Usable range	Hosts	Broadcast
`10.0.0.0/10`	`10.0.0.1` – `10.63.255.254`	4,194,302	`10.63.255.255`
`10.64.0.0/10`	`10.64.0.1` – `10.127.255.254`	4,194,302	`10.127.255.255`
`10.128.0.0/10`	`10.128.0.1` – `10.191.255.254`	4,194,302	`10.191.255.255`
`10.192.0.0/10`	`10.192.0.1` – `10.255.255.254`	4,194,302	`10.255.255.255`

Is this IP in the range?

Range to CIDR blocks

What to know

Sizes: 10.0.0.0/8 holds 16,777,216 addresses, 172.16.0.0/12 holds 1,048,576, and 192.168.0.0/16 holds 65,536. Any organization can use them without asking anyone, which is also why they collide when networks are connected.

Typical uses: home routers use 192.168.x.0/24; Docker uses 172.17.0.0/16 and other blocks from 172.16.0.0/12; AWS default VPCs are 172.31.0.0/16; corporate networks and cloud address plans usually come from 10.0.0.0/8.

The computed breakdown on this page is for 10.0.0.0/8. See also 172.16.0.0/12 and 192.168.0.0/16.

Gotchas

172.16.0.0/12 ends at 172.31.255.255. Addresses like 172.32.0.1 or 172.15.0.1 are public internet addresses, not private ones.
Plan ranges before you need VPNs or peering: two networks using the same private range cannot be routed to each other without NAT.
100.64.0.0/10 (carrier-grade NAT) and 169.254.0.0/16 (link-local) are also not publicly routable, but they are not RFC 1918 ranges and should not be used as general-purpose LAN space.

Related explainers

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