IP Subnet Calculator
Does IPv4 CIDR arithmetic in the browser. Paste address/prefix or an address plus a dotted mask, then read network, broadcast, netmask, wildcard, usable range, and host count. IPv4 only. Not a scanner.
IP subnet calculator
IPv4 CIDR math only, client-side, not a scanner, nothing is sent. This page does IPv4 CIDR arithmetic in the browser only.
How to use
- Enter an IPv4 CIDR such as 192.168.1.10/24, or an address plus a dotted mask such as 255.255.255.0.
- Read network, broadcast, netmask, wildcard, usable range, host count, and CIDR as text.
- Nothing is sent to a server. IPv4 only. Refreshing the page clears the form.
Results
Enter an IPv4 CIDR or address and dotted mask.
Runs in your browser. Nothing is uploaded.
Frequently asked questions
What is the difference between CIDR and a dotted mask?
CIDR writes an IPv4 address and a prefix, for example 192.168.1.10/24. A dotted mask writes the same prefix as four octets, for example 255.255.255.0, which is the same as /24. This page accepts either form and returns the same network, broadcast, mask, wildcard, usable range, and host count. The mask must be contiguous leading 1s then 0s.
What does 192.168.1.10/24 compute?
For 192.168.1.10/24 the network is 192.168.1.0, the broadcast is 192.168.1.255, and the mask is 255.255.255.0. The classic usable range is 192.168.1.1–192.168.1.254 (254 hosts). Address 192.168.1.10 with dotted mask 255.255.255.0 is the same /24 math. This is IPv4 CIDR arithmetic in the browser only.
How are /31 and /32 handled?
Prefix /31 is a point-to-point pair: two usable hosts, the two addresses in the block. Network and broadcast bits are still reported. Prefix /32 is a single address: network and broadcast equal that address, and the usable range is that one host. Prefixes 0–30 use classic usable hosts: network+1 through broadcast-1, host count 2^(32-prefix)-2.
Is this IPv4 only? Is it a scanner?
IPv4 only. IPv6 input fails closed. This page does IPv4 CIDR arithmetic in the browser only. It is not a scanner. It reports network, broadcast, mask, wildcard, usable range, and host count as text. It does not list every host.
Is this client-side? Do I need an account?
Yes, it is client-side only. There is no signup. Addresses never leave the browser. Tallymill does not save what you enter. Refreshing the page clears the form. Nothing is sent to a server.