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In-browser tool

IPv4 CIDR and subnet calculator

Enter an IPv4 address with a prefix length (for example 192.168.1.10/24) to view network address, subnet mask, wildcard mask, broadcast, address counts, and typical usable host bounds.

  • Updated: 2026-05-03
  • CIDR math runs locally in your browser. Values are not uploaded.
Enter CIDR and calculate.

How This Calculator Interprets Input

The tool applies standard IPv4 bitwise rules: it masks your address with the prefix length to find the network address, derives the subnet mask and wildcard mask, then computes broadcast and typical host bounds. It does not check whether the network is routable on the public internet, whether your address is the legally assigned origin, or how your firewall should treat the range. Always confirm results against your IPAM sheet or router configuration.

Privacy And Limitations

CIDR math runs locally in your browser. Values are not uploaded.

  • This page covers IPv4 CIDR only, not full IPv6 planning.
  • Output is educational and operational support; it is not a substitute for authoritative IPAM or router configuration review.
  • Special cases such as overlapping RFC 1918 space, BGP aggregates, or provider-specific rules still need network design context.

Related Pages

FAQ

What input format is supported?

IPv4 dotted decimal with slash prefix, for example 10.0.0.0/24.

Why might usable host counts differ from my router UI?

Some networks reserve additional addresses for gateways, HSRP/VRRP, or provider conventions beyond classic network and broadcast reservation.

How are /31 and /32 handled?

/32 is a single address. /31 follows common point-to-point conventions where both addresses may be usable on interfaces.

Is data sent to a server?

No. Calculations are performed locally in the browser.

Does this validate routing or DNS?

No. It only performs deterministic bit math on the address and prefix you supply.