16.18.100.0/25

Public

Class A — /25 prefix — 126 usable hosts

Network Address

16.18.100.0

Broadcast Address

16.18.100.127

Subnet Mask

255.255.255.128

Usable Hosts

126

First Usable IP

16.18.100.1

Last Usable IP

16.18.100.126

Total IPs

128

Prefix Length

/25

Network address — the base address of the block (16.18.100.0). All devices in this subnet share this prefix. Cannot be assigned to a host.

Broadcast address — packets sent to 16.18.100.127 are delivered to every device in the subnet. Also reserved — not assignable.

Usable hosts — the 126 addresses between those two that you can assign to servers, VMs, or interfaces.

Subnet mask — 255.255.255.128 is the dotted-decimal equivalent of /25. Older tools and Cisco configs use this format instead of CIDR slash notation.

Full Details

CIDR Notation	16.18.100.0/25
Network Address	16.18.100.0
Broadcast Address	16.18.100.127
Subnet Mask	255.255.255.128
Wildcard Mask	0.0.0.127
Prefix Length	/25
IP Address Class	Class A
Total IP Addresses	128
Usable Host Addresses	126
First Usable IP	16.18.100.1
Last Usable IP	16.18.100.126
Network (Hex)	0x10126400
Broadcast (Hex)	0x1012647F
Address Type	Public / Globally Routable

Binary Representation

Network Address

00010000.00010010.01100100 00010000.00010010.01100100.00000000

Subnet Mask

11111111.11111111.11111111.10000000

The first 25 bits (1s in the mask) identify the network. The remaining 7 bits identify hosts within the network.

Split into Equal Subnets

Split 16.18.100.0/25 into 2 equal /26 subnets (62 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	16.18.100.0/26	16.18.100.0	16.18.100.1	16.18.100.62	16.18.100.63	62
2	16.18.100.64/26	16.18.100.64	16.18.100.65	16.18.100.126	16.18.100.127	62

Split 16.18.100.0/25 into 4 equal /27 subnets (30 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	16.18.100.0/27	16.18.100.0	16.18.100.1	16.18.100.30	16.18.100.31	30
2	16.18.100.32/27	16.18.100.32	16.18.100.33	16.18.100.62	16.18.100.63	30
3	16.18.100.64/27	16.18.100.64	16.18.100.65	16.18.100.94	16.18.100.95	30
4	16.18.100.96/27	16.18.100.96	16.18.100.97	16.18.100.126	16.18.100.127	30

Split 16.18.100.0/25 into 8 equal /28 subnets (14 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	16.18.100.0/28	16.18.100.0	16.18.100.1	16.18.100.14	16.18.100.15	14
2	16.18.100.16/28	16.18.100.16	16.18.100.17	16.18.100.30	16.18.100.31	14
3	16.18.100.32/28	16.18.100.32	16.18.100.33	16.18.100.46	16.18.100.47	14
4	16.18.100.48/28	16.18.100.48	16.18.100.49	16.18.100.62	16.18.100.63	14
5	16.18.100.64/28	16.18.100.64	16.18.100.65	16.18.100.78	16.18.100.79	14
6	16.18.100.80/28	16.18.100.80	16.18.100.81	16.18.100.94	16.18.100.95	14
7	16.18.100.96/28	16.18.100.96	16.18.100.97	16.18.100.110	16.18.100.111	14
8	16.18.100.112/28	16.18.100.112	16.18.100.113	16.18.100.126	16.18.100.127	14

Split 16.18.100.0/25 into 16 equal /29 subnets (6 usable hosts each).

#	CIDR	Network	First Usable	Last Usable	Broadcast	Hosts
1	16.18.100.0/29	16.18.100.0	16.18.100.1	16.18.100.6	16.18.100.7	6
2	16.18.100.8/29	16.18.100.8	16.18.100.9	16.18.100.14	16.18.100.15	6
3	16.18.100.16/29	16.18.100.16	16.18.100.17	16.18.100.22	16.18.100.23	6
4	16.18.100.24/29	16.18.100.24	16.18.100.25	16.18.100.30	16.18.100.31	6
5	16.18.100.32/29	16.18.100.32	16.18.100.33	16.18.100.38	16.18.100.39	6
6	16.18.100.40/29	16.18.100.40	16.18.100.41	16.18.100.46	16.18.100.47	6
7	16.18.100.48/29	16.18.100.48	16.18.100.49	16.18.100.54	16.18.100.55	6
8	16.18.100.56/29	16.18.100.56	16.18.100.57	16.18.100.62	16.18.100.63	6
9	16.18.100.64/29	16.18.100.64	16.18.100.65	16.18.100.70	16.18.100.71	6
10	16.18.100.72/29	16.18.100.72	16.18.100.73	16.18.100.78	16.18.100.79	6
11	16.18.100.80/29	16.18.100.80	16.18.100.81	16.18.100.86	16.18.100.87	6
12	16.18.100.88/29	16.18.100.88	16.18.100.89	16.18.100.94	16.18.100.95	6
13	16.18.100.96/29	16.18.100.96	16.18.100.97	16.18.100.102	16.18.100.103	6
14	16.18.100.104/29	16.18.100.104	16.18.100.105	16.18.100.110	16.18.100.111	6
15	16.18.100.112/29	16.18.100.112	16.18.100.113	16.18.100.118	16.18.100.119	6
16	16.18.100.120/29	16.18.100.120	16.18.100.121	16.18.100.126	16.18.100.127	6

IP Address Sample

Showing first 16 of 128 total IPs.

16.18.100.0 net

16.18.100.1

16.18.100.2

16.18.100.3

16.18.100.4

16.18.100.5

16.18.100.6

16.18.100.7

16.18.100.8

16.18.100.9

16.18.100.10

16.18.100.11

16.18.100.12

16.18.100.13

16.18.100.14

16.18.100.15

… 112 more IPs …

/25 Subnet Reference

Total IPs 128

Usable Hosts 126

Subnet Mask 255.255.255.128

Wildcard 0.0.0.127

Full /25 reference →

Related Ranges

Parent /24 block 16.18.100.0/24 Sibling /25 block 16.18.100.128/25

Adjacent Prefix Sizes

/23 510 hosts /24 254 hosts /25 126 hosts /26 62 hosts /27 30 hosts