Calculateur CIDR / de sous-réseaux
Décomposez n'importe quel bloc CIDR IPv4 en adresses de réseau et de diffusion, plage d'hôtes utilisables, nombre d'hôtes et masque de réseau, et voyez dans quelle plage à usage spécial de l'IANA il se trouve. Les autres modes découpent un bloc parent en sous-réseaux de longueur variable (VLSM), agrègent des préfixes en un super-réseau et repèrent les chevauchements et les trous. S'exécute entièrement dans votre navigateur.
RéseauCalculateur CIDR
Analyse un seul bloc CIDR IPv4 : réseau, diffusion, masque, plage d'hôtes et les plages à usage spécial dans lesquelles il tombe ou qu'il chevauche.
S'exécute localement. Rien n'est envoyé à un serveur.
What this page needs
This tool computes entirely on your device, so nothing you type is sent anywhere. That local computation needs JavaScript; CSS is used for layout and theming.
This tool is built to also work over an HTTP API. Processing is currently off, so the API is documented but not served; when it is switched on, you will be able to call it without a browser.
All results are computed locally from the blocks you enter, using standard IPv4 addressing arithmetic: one block's network, mask, host range and counts (a /31 counts two usable hosts, RFC 3021); variable-length subnets carved from a parent, largest block first, with the free space left as blocks; the minimal aggregate and single supernet of a list; and the overlaps and gaps among prefixes. The special-purpose classification compares a block with an embedded copy of the IANA IPv4 Special-Purpose Address Space registry, read on 2026-10-19, plus the multicast range 224.0.0.0/4; nothing is looked up remotely and nothing is sent anywhere. Behaviour is pinned by 26 golden vectors.
- RFC 4632 (CIDR)Classless Inter-Domain Routing: prefix notation, block sizes and aggregation
- RFC 1122, section 3.2.1.3The network and broadcast addresses a /0 to /30 block reserves
- RFC 302131-bit prefixes on point-to-point links: both addresses are hosts
- IANA IPv4 Special-Purpose Address SpaceEvery row of the special-purpose classification, with its flags (registry updated 2025-10-09, read 2026-10-19)
- RFC 6890Special-Purpose IP Address Registries: the registry's structure and flag columns (updated by RFC 8190)
- RFC 1918Private address ranges
- RFC 791 (IPv4)The Internet Protocol