How many addresses are in a /13 block?

A /13 block contains 524,288 total addresses (2^19) and 524,286 usable hosts.

What is the subnet mask for /13?

The subnet mask for /13 is 255.248.0.0 (binary: 11111111.11111000.00000000.00000000). The wildcard mask is 0.7.255.255.

How many /16 networks fit inside a /13?

A /13 contains 2^3 = 8 individual /16 networks, each capable of supporting 65,534 hosts.

When would you use a /13 in address planning?

When you need to allocate a block between the /12 and /16 size. For example, dividing the 172.16.0.0/12 private range into two halves gives 172.16.0.0/13 and 172.24.0.0/13, each covering 8 /16 blocks.

How many /24 subnets fit in a /13?

A /13 block contains 2^11 = 2,048 individual /24 subnets.

/13 Subnet Calculator

Results update as you type

A /13 block contains 524,288 addresses. Seen in ISP allocations and in splitting large enterprise address spaces into manageable regional blocks.

Network size

/32

/13 = mask 255.248.0.0 • 524,286 usable addresses

Results for 10.0.0.0/13

Private (RFC 1918)Class A

Network addressThe first address — identifies the subnet itself

Broadcast addressThe last address — used to reach every device at once

Subnet maskSame as /13 in CIDR notation

First usable hostThe first IP you can assign to a device

Last usable hostThe last IP you can assign to a device

Usable hosts524,288 total addresses in this subnet

More detailsNeighboring subnets, wildcard mask, hex, reverse DNS, and binary breakdown

Neighboring /13 subnets

Wildcard mask: Used in Cisco ACLs and OSPF
CIDR notation
IP in hexadecimal
IP as 32-bit integer
Reverse DNS (PTR)
Host bits / subnet bits

Binary breakdown

IP address00001010.00000000.00000000.00000000

Subnet mask11111111.11111000.00000000.00000000

Network00001010.00000000.00000000.00000000

Broadcast00001010.00000111.11111111.11111111

Quick facts for /13

Subnet mask: 255.248.0.0
Wildcard: 0.7.255.255
Usable hosts: 524,286
Total addresses: 524,288

/13 reference guideBit split, overview, sizing tables, notable networks, and FAQ

Binary bit split

11111111·11111000·00000000·00000000

Network bits (13)Host bits (19)

Network bits: 13
Host bits: 19
Subnet mask: 255.248.0.0
Wildcard mask: 0.7.255.255
Total addresses: 524,288
Usable hosts: 524,286
Hosts formula: 2^19 − 2
/24 relationship: 2,048 × /24 networks

Overview

A /13 block contains 524,288 addresses. Seen in ISP allocations and in splitting large enterprise address spaces into manageable regional blocks.

Common use cases

ISP address block allocation
Regional enterprise address blocks
Large data center aggregate addressing

Subnet sizing reference

Divide /13 into…

Prefix	Subnets	Hosts each
/14	2	262,142
/15	4	131,070
/16	8	65,534
/17	16	32,766

/13 fits inside…

Supernet	Hosts	/13s inside
/12	1,048,574	2
/11	2,097,150	4
/10	4,194,302	8
/9	8,388,606	16

Frequently asked questions

Common questions about /13 networks, subnet masks, and use cases.

All CIDR prefix sizes

/0 /1 /2 /3 /4 /5 /6 /7 /8 /9 /10 /11 /12 /13 /14 /15 /16 /17 /18 /19 /20 /21 /22 /23 /24 /25 /26 /27 /28 /29 /30 /31 /32