IPv4/IPv6 Subnet Chart
Complete reference for CIDR notation, subnet masks, and address classes.
IPv4 CIDR Chart
/32 to /0 Reference
Private & Special Ranges
RFC 1918 & Classes
IPv6 Subnet Chart
Prefixes & Special Addresses
What this section provides
This page provides reference tables for IPv4 and IPv6 addressing. It lists standard CIDR notations, subnet masks, wildcard masks, and usable host counts for quick lookup.
When engineers use this
- Quickly identifying the subnet mask or wildcard mask for a specific CIDR prefix.
- Determining the number of usable hosts in a subnet during capacity planning.
- Referencing private IP address ranges (RFC 1918) and special use blocks.
IPv4 CIDR Subnet Chart
| CIDR | Subnet Mask | Wildcard | Hosts | Usable |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 0.0.0.0 | 1 | 1 (Host) |
| /31 | 255.255.255.254 | 0.0.0.1 | 2 | 2 (P2P) |
| /30 | 255.255.255.252 | 0.0.0.3 | 4 | 2 |
| /29 | 255.255.255.248 | 0.0.0.7 | 8 | 6 |
| /28 | 255.255.255.240 | 0.0.0.15 | 16 | 14 |
| /27 | 255.255.255.224 | 0.0.0.31 | 32 | 30 |
| /26 | 255.255.255.192 | 0.0.0.63 | 64 | 62 |
| /25 | 255.255.255.128 | 0.0.0.127 | 128 | 126 |
| /24 | 255.255.255.0 | 0.0.0.255 | 256 | 254 |
| /23 | 255.255.254.0 | 0.0.1.255 | 512 | 510 |
| /22 | 255.255.252.0 | 0.0.3.255 | 1,024 | 1,022 |
| /21 | 255.255.248.0 | 0.0.7.255 | 2,048 | 2,046 |
| /20 | 255.255.240.0 | 0.0.15.255 | 4,096 | 4,094 |
| /19 | 255.255.224.0 | 0.0.31.255 | 8,192 | 8,190 |
| /18 | 255.255.192.0 | 0.0.63.255 | 16,384 | 16,382 |
| /17 | 255.255.128.0 | 0.0.127.255 | 32,768 | 32,766 |
| /16 | 255.255.0.0 | 0.0.255.255 | 65,536 | 65,534 |
| /15 | 255.254.0.0 | 0.1.255.255 | 131,072 | 131,070 |
| /14 | 255.252.0.0 | 0.3.255.255 | 262,144 | 262,142 |
| /13 | 255.248.0.0 | 0.7.255.255 | 524,288 | 524,286 |
| /12 | 255.240.0.0 | 0.15.255.255 | 1,048,576 | 1,048,574 |
| /11 | 255.224.0.0 | 0.31.255.255 | 2,097,152 | 2,097,150 |
| /10 | 255.192.0.0 | 0.63.255.255 | 4,194,304 | 4,194,302 |
| /9 | 255.128.0.0 | 0.127.255.255 | 8,388,608 | 8,388,606 |
| /8 | 255.0.0.0 | 0.255.255.255 | 16,777,216 | 16,777,214 |
| /7 | 254.0.0.0 | 1.255.255.255 | 33,554,432 | 33,554,430 |
| /6 | 252.0.0.0 | 3.255.255.255 | 67,108,864 | 67,108,862 |
| /5 | 248.0.0.0 | 7.255.255.255 | 134,217,728 | 134,217,726 |
| /4 | 240.0.0.0 | 15.255.255.255 | 268,435,456 | 268,435,454 |
| /0 | 0.0.0.0 | 255.255.255.255 | 4.29 Billion | All |
Private IP Ranges (RFC 1918)
| Class | IP Range | CIDR | Mask | Description |
|---|---|---|---|---|
| Class A | 10.0.0.0 - 10.255.255.255 | 10.0.0.0/8 | 255.0.0.0 | Large Enterprise / ISP |
| Class B | 172.16.0.0 - 172.31.255.255 | 172.16.0.0/12 | 255.240.0.0 | Medium Enterprise / Cloud |
| Class C | 192.168.0.0 - 192.168.255.255 | 192.168.0.0/16 | 255.255.0.0 | Small Office / Home |
| APIPA | 169.254.0.0 - 169.254.255.255 | 169.254.0.0/16 | 255.255.0.0 | Link-Local (Auto Config) |
IPv4 Address Classes
| Class | Range | Default CIDR | Usage |
|---|---|---|---|
| Class A | 1.0.0.0 - 126.255.255.255 | /8 | Large Organizations |
| Class B | 128.0.0.0 - 191.255.255.255 | /16 | Medium Organizations |
| Class C | 192.0.0.0 - 223.255.255.255 | /24 | Small Networks |
| Class D | 224.0.0.0 - 239.255.255.255 | N/A | Multicast |
| Class E | 240.0.0.0 - 255.255.255.255 | N/A | Reserved / Experimental |
Special Use Ranges
| Range | CIDR | Purpose | RFC |
|---|---|---|---|
| 0.0.0.0 - 0.255.255.255 | 0.0.0.0/8 | Current Network (Source Only) | RFC 1122 |
| 127.0.0.0 - 127.255.255.255 | 127.0.0.0/8 | Loopback (Localhost) | RFC 1122 |
| 100.64.0.0 - 100.127.255.255 | 100.64.0.0/10 | Carrier Grade NAT (CGNAT) | RFC 6598 |
| 192.0.0.0 - 192.0.0.255 | 192.0.0.0/24 | IETF Protocol Assignments | RFC 6890 |
| 192.0.2.0 - 192.0.2.255 | 192.0.2.0/24 | Documentation (TEST-NET-1) | RFC 5737 |
| 198.51.100.0 - 198.51.100.255 | 198.51.100.0/24 | Documentation (TEST-NET-2) | RFC 5737 |
| 203.0.113.0 - 203.0.113.255 | 203.0.113.0/24 | Documentation (TEST-NET-3) | RFC 5737 |
IPv6 Reference
IPv6 CIDR & Subnetting Chart
| Prefix | Net Bits | Host Bits | Total Addresses | /64 Subnets | Usage |
|---|---|---|---|---|---|
| /128 | 128 | 0 | 1 | 0 | Host address |
| /127 | 127 | 1 | 2 | 0 | Point-to-point links |
| /126 | 126 | 2 | 4 | 0 | Point-to-point links |
| /125 | 125 | 3 | 8 | 0 | Very small subnets |
| /124 | 124 | 4 | 16 | 0 | Very small subnets |
| /120 | 120 | 8 | 256 | 0 | Small subnets |
| /112 | 112 | 16 | 65,536 | 0 | Small networks |
| /96 | 96 | 32 | 4,294,967,296 | 0 | Large subnets |
| /64 | 64 | 64 | 1.8 x 10^19 | 1 | Standard subnet |
| /56 | 56 | 72 | 4.7 x 10^21 | 256 | Site allocation |
| /48 | 48 | 80 | 1.2 x 10^24 | 65,536 | Organization |
| /40 | 40 | 88 | 3.1 x 10^26 | 16,777,216 | Large organization |
| /32 | 32 | 96 | 7.9 x 10^28 | 4,294,967,296 | ISP allocation |
| /24 | 24 | 104 | 2.0 x 10^31 | 1.1 x 10^12 | Regional registry |
| /16 | 16 | 112 | 5.2 x 10^33 | 2.8 x 10^14 | Global registry |
| /12 | 12 | 116 | 8.3 x 10^34 | 4.5 x 10^15 | Special allocation |
| /8 | 8 | 120 | 1.3 x 10^36 | 7.2 x 10^16 | Address type |
| /4 | 4 | 124 | 2.1 x 10^37 | 1.2 x 10^18 | Address class |
| /3 | 3 | 125 | 4.2 x 10^37 | 2.3 x 10^18 | Global unicast |
| /0 | 0 | 128 | 3.4 x 10^38 | 1.8 x 10^19 | Entire IPv6 space |
IPv6 Unicast Address Types
| Type | Prefix | Description | Scope |
|---|---|---|---|
| Global Unicast | 2000::/3 | Internet routable addresses | Global |
| Link-Local | fe80::/10 | Not routable beyond local link | Link |
| Unique Local (ULA) | fc00::/7 | Private addresses for local use | Local |
| Loopback | ::1/128 | Localhost address | Node |
| Unspecified | ::/128 | All zeros address | Node |
| IPv4-mapped | ::ffff:0:0/96 | IPv4 addresses mapped to IPv6 | Global |
| IPv4-compatible | ::/96 | Deprecated IPv4 compatibility | Global |
IPv6 Multicast Scopes
| Type | Prefix | Description | Examples |
|---|---|---|---|
| Interface-local | ff01::/16 | Single interface only | ff01::1 (All Nodes) |
| Link-local | ff02::/16 | Single link/subnet | ff02::1 (All Nodes), ff02::2 (All Routers) |
| Site-local | ff05::/16 | Single site/organization | ff05::2 (All Routers) |
| Organization-local | ff08::/16 | Single organization | ff08::fb (mDNSv6) |
| Global | ff0e::/16 | Global Internet | ff0e::1 (NTP) |
| Solicited-node | ff02::1:ff00:0/104 | Neighbor Discovery | ff02::1:ffxx:xxxx |
IPv6 Special & Reserved Ranges
| Prefix | Purpose | RFC | Status |
|---|---|---|---|
| ::/8 | Special Use | RFC 4291 | Reserved |
| 0100::/8 | Reserved | RFC 4291 | Reserved |
| 0200::/7 | Reserved | RFC 4291 | Reserved |
| 0400::/6 | Reserved | RFC 4291 | Reserved |
| 0800::/5 | Reserved | RFC 4291 | Reserved |
| 1000::/4 | Reserved | RFC 4291 | Reserved |
| 4000::/3 | Reserved | RFC 4291 | Reserved |
| 6000::/3 | Reserved | RFC 4291 | Reserved |
| 8000::/3 | Reserved | RFC 4291 | Reserved |
| a000::/3 | Reserved | RFC 4291 | Reserved |
| c000::/3 | Reserved | RFC 4291 | Reserved |
| e000::/4 | Reserved | RFC 4291 | Reserved |
| f000::/5 | Reserved | RFC 4291 | Reserved |
| f800::/6 | Reserved | RFC 4291 | Reserved |
| fc00::/7 | Unique Local | RFC 4193 | Active |
| fe00::/9 | Reserved | RFC 4291 | Reserved |
| fe80::/10 | Link-Local | RFC 4291 | Active |
| fec0::/10 | Site-Local | RFC 3879 | Deprecated |
| ff00::/8 | Multicast | RFC 4291 | Active |