IP Subnet Calculator for IPv4 and IPv6

Dual-stack network planning

IPv4 and IPv6 subnet calculator

Inspect an address, convert CIDR and netmask notation, and enumerate a bounded parent IPv4 block. All work stays in this browser; this tool does not scan a live network.

IP versionIPV4IPV6

IPv4 sample result is ready.

IPv4 inputs

Address and subnet scope

IPv4 addressDotted IPv4, optionally with a matching CIDR suffix.

Subnet mask / CIDRExamples: /30, 30, or 255.255.255.252.

Parent CIDR for subnet tableThe parent must contain the IP and produce at most 4,096 child rows.

Legacy class filter (optional)

AnyABC

Classful networking is obsolete. This optional check never changes CIDR math.

IPv4 result

183.195.98.180/30

Usable range183.195.98.181 – 183.195.98.182

Broadcast183.195.98.183

Addresses / usable4.00 / 2.00

Traditional subnet arithmetic excludes the network and directed-broadcast addresses. Real platforms may reserve additional addresses.

Full IPv4 address details

IP address: 183.195.98.180
Network address: 183.195.98.180
First usable address: 183.195.98.181
Last usable address: 183.195.98.182
Broadcast address: 183.195.98.183
Total addresses: 4.00
Usable hosts / endpoints: 2.00
Subnet mask: 255.255.255.252
Wildcard mask: 0.0.0.3
Binary subnet mask: 11111111111111111111111111111100
Historical IP class: B (obsolete classful label)
CIDR notation: /30
IP type: Public unicast
Short notation: 183.195.98.180/30
Entered address role: Network address
Binary ID: 10110111110000110110001010110100
Integer ID: 3083035316
Hex ID: 0xb7c362b4
Reverse DNS: 180.98.195.183.in-addr.arpa
IPv4-mapped IPv6: ::ffff:b7c3:62b4
Legacy 6to4 prefix: 2002:b7c3:62b4::/48

Bounded parent-to-child enumeration

All 64 /30 networks in 183.195.98.0/24

This bounded table divides the parent CIDR into the selected child prefix. It does not scan, reserve, or test addresses on a live network.

Network CIDR	Usable host / endpoint range	Broadcast
`183.195.98.0/30`	`183.195.98.1 – 183.195.98.2`	`183.195.98.3`
`183.195.98.4/30`	`183.195.98.5 – 183.195.98.6`	`183.195.98.7`
`183.195.98.8/30`	`183.195.98.9 – 183.195.98.10`	`183.195.98.11`
`183.195.98.12/30`	`183.195.98.13 – 183.195.98.14`	`183.195.98.15`
`183.195.98.16/30`	`183.195.98.17 – 183.195.98.18`	`183.195.98.19`
`183.195.98.20/30`	`183.195.98.21 – 183.195.98.22`	`183.195.98.23`
`183.195.98.24/30`	`183.195.98.25 – 183.195.98.26`	`183.195.98.27`
`183.195.98.28/30`	`183.195.98.29 – 183.195.98.30`	`183.195.98.31`
`183.195.98.32/30`	`183.195.98.33 – 183.195.98.34`	`183.195.98.35`
`183.195.98.36/30`	`183.195.98.37 – 183.195.98.38`	`183.195.98.39`
`183.195.98.40/30`	`183.195.98.41 – 183.195.98.42`	`183.195.98.43`
`183.195.98.44/30`	`183.195.98.45 – 183.195.98.46`	`183.195.98.47`
`183.195.98.48/30`	`183.195.98.49 – 183.195.98.50`	`183.195.98.51`
`183.195.98.52/30`	`183.195.98.53 – 183.195.98.54`	`183.195.98.55`
`183.195.98.56/30`	`183.195.98.57 – 183.195.98.58`	`183.195.98.59`
`183.195.98.60/30`	`183.195.98.61 – 183.195.98.62`	`183.195.98.63`
`183.195.98.64/30`	`183.195.98.65 – 183.195.98.66`	`183.195.98.67`
`183.195.98.68/30`	`183.195.98.69 – 183.195.98.70`	`183.195.98.71`
`183.195.98.72/30`	`183.195.98.73 – 183.195.98.74`	`183.195.98.75`
`183.195.98.76/30`	`183.195.98.77 – 183.195.98.78`	`183.195.98.79`
`183.195.98.80/30`	`183.195.98.81 – 183.195.98.82`	`183.195.98.83`
`183.195.98.84/30`	`183.195.98.85 – 183.195.98.86`	`183.195.98.87`
`183.195.98.88/30`	`183.195.98.89 – 183.195.98.90`	`183.195.98.91`
`183.195.98.92/30`	`183.195.98.93 – 183.195.98.94`	`183.195.98.95`
`183.195.98.96/30`	`183.195.98.97 – 183.195.98.98`	`183.195.98.99`
`183.195.98.100/30`	`183.195.98.101 – 183.195.98.102`	`183.195.98.103`
`183.195.98.104/30`	`183.195.98.105 – 183.195.98.106`	`183.195.98.107`
`183.195.98.108/30`	`183.195.98.109 – 183.195.98.110`	`183.195.98.111`
`183.195.98.112/30`	`183.195.98.113 – 183.195.98.114`	`183.195.98.115`
`183.195.98.116/30`	`183.195.98.117 – 183.195.98.118`	`183.195.98.119`
`183.195.98.120/30`	`183.195.98.121 – 183.195.98.122`	`183.195.98.123`
`183.195.98.124/30`	`183.195.98.125 – 183.195.98.126`	`183.195.98.127`
`183.195.98.128/30`	`183.195.98.129 – 183.195.98.130`	`183.195.98.131`
`183.195.98.132/30`	`183.195.98.133 – 183.195.98.134`	`183.195.98.135`
`183.195.98.136/30`	`183.195.98.137 – 183.195.98.138`	`183.195.98.139`
`183.195.98.140/30`	`183.195.98.141 – 183.195.98.142`	`183.195.98.143`
`183.195.98.144/30`	`183.195.98.145 – 183.195.98.146`	`183.195.98.147`
`183.195.98.148/30`	`183.195.98.149 – 183.195.98.150`	`183.195.98.151`
`183.195.98.152/30`	`183.195.98.153 – 183.195.98.154`	`183.195.98.155`
`183.195.98.156/30`	`183.195.98.157 – 183.195.98.158`	`183.195.98.159`
`183.195.98.160/30`	`183.195.98.161 – 183.195.98.162`	`183.195.98.163`
`183.195.98.164/30`	`183.195.98.165 – 183.195.98.166`	`183.195.98.167`
`183.195.98.168/30`	`183.195.98.169 – 183.195.98.170`	`183.195.98.171`
`183.195.98.172/30`	`183.195.98.173 – 183.195.98.174`	`183.195.98.175`
`183.195.98.176/30`	`183.195.98.177 – 183.195.98.178`	`183.195.98.179`
`183.195.98.180/30`Entered IP	`183.195.98.181 – 183.195.98.182`	`183.195.98.183`
`183.195.98.184/30`	`183.195.98.185 – 183.195.98.186`	`183.195.98.187`
`183.195.98.188/30`	`183.195.98.189 – 183.195.98.190`	`183.195.98.191`
`183.195.98.192/30`	`183.195.98.193 – 183.195.98.194`	`183.195.98.195`
`183.195.98.196/30`	`183.195.98.197 – 183.195.98.198`	`183.195.98.199`
`183.195.98.200/30`	`183.195.98.201 – 183.195.98.202`	`183.195.98.203`
`183.195.98.204/30`	`183.195.98.205 – 183.195.98.206`	`183.195.98.207`
`183.195.98.208/30`	`183.195.98.209 – 183.195.98.210`	`183.195.98.211`
`183.195.98.212/30`	`183.195.98.213 – 183.195.98.214`	`183.195.98.215`
`183.195.98.216/30`	`183.195.98.217 – 183.195.98.218`	`183.195.98.219`
`183.195.98.220/30`	`183.195.98.221 – 183.195.98.222`	`183.195.98.223`
`183.195.98.224/30`	`183.195.98.225 – 183.195.98.226`	`183.195.98.227`
`183.195.98.228/30`	`183.195.98.229 – 183.195.98.230`	`183.195.98.231`
`183.195.98.232/30`	`183.195.98.233 – 183.195.98.234`	`183.195.98.235`
`183.195.98.236/30`	`183.195.98.237 – 183.195.98.238`	`183.195.98.239`
`183.195.98.240/30`	`183.195.98.241 – 183.195.98.242`	`183.195.98.243`
`183.195.98.244/30`	`183.195.98.245 – 183.195.98.246`	`183.195.98.247`
`183.195.98.248/30`	`183.195.98.249 – 183.195.98.250`	`183.195.98.251`
`183.195.98.252/30`	`183.195.98.253 – 183.195.98.254`	`183.195.98.255`

Address boundaries before device configuration

Turn a CIDR result into an address plan you can operate

A subnet calculator reveals mathematical boundaries, masks, ranges, and counts. A deployable plan still needs address roles, routing intent, DHCP exclusions, security policy, inventory, and validation on the actual network.

Side-by-side guide · Address boundaries before device configuration

Three endpoint rules that prevent off-by-two mistakes

IPv4 width: 32 bits; /24 contains 256 addresses
IPv4 point to point: /31 can identify two link endpoints
IPv6 width: 128 bits and no broadcast address

Ordinary IPv4 subnet
For a conventional multi-access prefix such as /24 or /30, the all-zero host field identifies the network and the all-one host field is the directed broadcast. That leaves 254 traditional host positions in a /24 and two in a /30, before local reservations are considered.
IPv4 /31 point-to-point link
RFC 3021 defines both addresses as host addresses when /31 is deliberately used on a point-to-point link. There is no separate directed-broadcast endpoint on that link. This is a topology-specific use, not permission to treat every two-address segment as an ordinary LAN.
IPv6 prefix
IPv6 addresses are 128 bits, and RFC 4291 defines unicast, anycast, and multicast but no broadcast address. Do not subtract two from the IPv6 count. Address architecture, interface identifier policy, neighbor discovery, and local assignment practice remain separate from the raw number of addresses.

Turn a CIDR result into an address plan you can operate: Do not apply the traditional IPv4 usable-host shortcut to every prefix or to IPv6.

CIDR draws a bit boundary, not a list of active machines

In IPv4 CIDR notation, the number after the slash states how many of the 32 address bits form the significant prefix. The remaining bits enumerate positions inside that block. A /24 therefore leaves eight host-side bits and contains 2⁸, or 256, addresses. The exponent calculator can verify that isolated power-of-two capacity arithmetic, while this page applies it to network boundaries and address roles. RFC 4632 describes those classless prefixes as bit-aligned power-of-two blocks; familiar class A, B, and C names are historical shortcuts, not the arithmetic used by a modern prefix.

The network address is obtained by keeping the prefix bits and setting the remaining IPv4 bits to zero. The traditional directed-broadcast address sets them to one. Ordinary multi-access IPv4 subnet planning often excludes those two endpoints from host assignment, but that rule has explicit exceptions. The calculator reports roles from the entered prefix; it does not discover whether any address answers, belongs to DHCP, is reserved in an IP address management system, or is routed through the intended interface.

Three endpoint rules that prevent off-by-two mistakes

Do not apply the traditional IPv4 usable-host shortcut to every prefix or to IPv6.

Ordinary IPv4 subnet

For a conventional multi-access prefix such as /24 or /30, the all-zero host field identifies the network and the all-one host field is the directed broadcast. That leaves 254 traditional host positions in a /24 and two in a /30, before local reservations are considered.

IPv4 /31 point-to-point link

RFC 3021 defines both addresses as host addresses when /31 is deliberately used on a point-to-point link. There is no separate directed-broadcast endpoint on that link. This is a topology-specific use, not permission to treat every two-address segment as an ordinary LAN.

IPv6 prefix

IPv6 addresses are 128 bits, and RFC 4291 defines unicast, anycast, and multicast but no broadcast address. Do not subtract two from the IPv6 count. Address architecture, interface identifier policy, neighbor discovery, and local assignment practice remain separate from the raw number of addresses.

From one parent block to an auditable allocation table

Confirm authority and containment
Start with a parent prefix you are authorized to use. Verify that the proposed child prefix is longer than or equal to the parent and that every generated child range remains inside it. A calculator cannot grant ownership of public space or change an upstream route.
Size by roles, not today's ping replies
Count infrastructure, clients, static reservations, DHCP growth, high-availability peers, and a documented reserve. Use the percentage calculator when historical inventory must be converted into a growth rate, then choose the next power-of-two block that satisfies the policy rather than the smallest block that happens to fit today.
Record every boundary
For each child prefix, store the network, prefix length, mask where relevant, first and last assignment positions, gateway convention, VLAN or interface, DHCP scope, exclusions, DNS domain, owner, and purpose. Keep the mathematical output and the operational decisions in separate columns.
Stage configuration and rollback
Check route summaries, access-control rules, NAT, DHCP, DNS, monitoring, and any overlapping VPN ranges before change. For a multi-site cutover, the time zone calculator can express the same scheduled instant for teams in different zones; it does not replace the change record or maintenance approval.

What the range table deliberately cannot tell you

Reachability: the page performs address arithmetic and does not send packets, resolve names, or scan the entered network.
Availability: an address inside the calculated range may already be leased, statically assigned, reserved, filtered, translated, or documented elsewhere.
Route correctness: a valid child prefix can still overlap another site, be advertised from the wrong place, or be absent from forwarding tables.
Security: subnet boundaries do not automatically create firewall policy, tenant isolation, authentication, or least-privilege access.
Service quality: address capacity does not predict latency, loss, jitter, Wi-Fi contention, internet transit, or application throughput.

Validate the service after the address plan is applied

Verify configuration from the intended segment: interface address and prefix, default gateway, DNS, DHCP behavior, expected routes, and permitted application paths. Compare the observed state with the allocation table rather than assuming that a syntactically valid configuration reached every device.

When users report a slow application after the change, use an independently operated network measurement service only for the narrower question it answers: an on-demand sample of latency, jitter, upload, and download throughput between the browser and that service. It is not a LAN scanner or proof that another destination is healthy. Keep addressing, routing, access policy, and measured performance as connected but separately evidenced layers.

Important limitations

This tool performs deterministic address arithmetic only. It does not discover devices, query routing or DNS state, apply a cloud provider's reserved-address policy, validate firewall rules, or confirm that a proposed subnet is safe to deploy. Verify production changes against the relevant platform and current network design.

This formula passed its registered engineering tests and is published under an explicit site-owner policy authorization. No independent expert, QA, editorial, legal, or third-party review is claimed. Verify consequential results with a qualified professional.

Address boundaries before device configuration

Turn a CIDR result into an address plan you can operate

Side-by-side guide · Address boundaries before device configuration

Three endpoint rules that prevent off-by-two mistakes

IPv4 width: 32 bits; /24 contains 256 addresses
IPv4 point to point: /31 can identify two link endpoints
IPv6 width: 128 bits and no broadcast address

Ordinary IPv4 subnet
For a conventional multi-access prefix such as /24 or /30, the all-zero host field identifies the network and the all-one host field is the directed broadcast. That leaves 254 traditional host positions in a /24 and two in a /30, before local reservations are considered.
IPv4 /31 point-to-point link
RFC 3021 defines both addresses as host addresses when /31 is deliberately used on a point-to-point link. There is no separate directed-broadcast endpoint on that link. This is a topology-specific use, not permission to treat every two-address segment as an ordinary LAN.
IPv6 prefix
IPv6 addresses are 128 bits, and RFC 4291 defines unicast, anycast, and multicast but no broadcast address. Do not subtract two from the IPv6 count. Address architecture, interface identifier policy, neighbor discovery, and local assignment practice remain separate from the raw number of addresses.

Turn a CIDR result into an address plan you can operate: Do not apply the traditional IPv4 usable-host shortcut to every prefix or to IPv6.

CIDR draws a bit boundary, not a list of active machines

Three endpoint rules that prevent off-by-two mistakes

Do not apply the traditional IPv4 usable-host shortcut to every prefix or to IPv6.

Ordinary IPv4 subnet

IPv4 /31 point-to-point link

IPv6 prefix

From one parent block to an auditable allocation table

Confirm authority and containment
Start with a parent prefix you are authorized to use. Verify that the proposed child prefix is longer than or equal to the parent and that every generated child range remains inside it. A calculator cannot grant ownership of public space or change an upstream route.
Size by roles, not today's ping replies
Count infrastructure, clients, static reservations, DHCP growth, high-availability peers, and a documented reserve. Use the percentage calculator when historical inventory must be converted into a growth rate, then choose the next power-of-two block that satisfies the policy rather than the smallest block that happens to fit today.
Record every boundary
For each child prefix, store the network, prefix length, mask where relevant, first and last assignment positions, gateway convention, VLAN or interface, DHCP scope, exclusions, DNS domain, owner, and purpose. Keep the mathematical output and the operational decisions in separate columns.
Stage configuration and rollback
Check route summaries, access-control rules, NAT, DHCP, DNS, monitoring, and any overlapping VPN ranges before change. For a multi-site cutover, the time zone calculator can express the same scheduled instant for teams in different zones; it does not replace the change record or maintenance approval.

What the range table deliberately cannot tell you

Reachability: the page performs address arithmetic and does not send packets, resolve names, or scan the entered network.
Availability: an address inside the calculated range may already be leased, statically assigned, reserved, filtered, translated, or documented elsewhere.
Route correctness: a valid child prefix can still overlap another site, be advertised from the wrong place, or be absent from forwarding tables.
Security: subnet boundaries do not automatically create firewall policy, tenant isolation, authentication, or least-privilege access.
Service quality: address capacity does not predict latency, loss, jitter, Wi-Fi contention, internet transit, or application throughput.