An IPv4 address is really just a 32-bit number written in a friendly dotted-decimal form. This converter reads each of the four octets, checks that every one is between 0 and 255, and packs them into a single unsigned 32-bit integer using bit shifts — exactly how databases, geolocation tables and firewalls store addresses so ranges can be compared with simple integer math. It also shows the hexadecimal form (for example 0xC0A80101) that appears in packet dumps and configuration files.
Converting the other way, type any integer from 0 to 4294967295 (or a 0x-prefixed hex value) and it is unpacked back into the four octets. Illegal input — a wrong octet count, an octet above 255, or an integer out of range — is reported instead of producing a bogus result. Everything runs locally in your browser and nothing is uploaded.
Subnet / CIDR CalculatorIP Address LookupNumber Base Converter