IPv4 Range Calculator
The IPv4 range calculator works in the opposite direction of a subnet calculator: you give it a start and end IP address, and it returns the most efficient set of CIDR blocks that covers the entire range without overlap.
This is useful whenever you have a flat list of addresses - a DHCP pool, a block of public IPs from an ISP, or a legacy allocation - and need to express it as clean CIDR notation for routing or documentation.
IPv4 Range Calculator
Find the CIDR notation (or notations) that covers a given IP range.
Enter values above to see results.
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More Tools
Explore the other tools in the toolkit.
Subnet Calculator
Free subnet calculator: enter an IP address and CIDR prefix to get the network address, broadcast address, subnet mask, usable IP range, and host count instantly.
CIDR Calculator
Free CIDR calculator: convert any prefix length from /0 to /32 into its dotted-decimal subnet mask, binary mask, wildcard mask, and total usable hosts.
VLAN Capacity Calculator
Free VLAN capacity calculator: determine the subnet size you need for your number of VLANs and devices per VLAN, including growth headroom.
Rack Power Calculator
Free rack power calculator: estimate total watts, BTU/hr, amps at 120V and 240V, cooling tons, and watts per feed for the equipment in your racks.
UPS Runtime Calculator
Free UPS runtime calculator: estimate how long your UPS battery will run under load based on wattage, battery capacity, voltage, and inverter efficiency.
BTU Calculator
Free BTU calculator: convert electrical watts to BTU/hr and the tons of cooling required for your data center, server room, or network closet.
Subnet Overlap Checker
Free subnet overlap checker: paste a list of CIDR blocks and instantly see every pair that shares addresses, before conflicts cause routing or IP assignment problems.
IPv6 Subnet Calculator
Free IPv6 subnet calculator: enter an IPv6 address and prefix length to get the network address, expanded form, total addresses, and the number of /64 subnets.
Batch CIDR Converter
Free batch CIDR converter: paste a list of subnets as CIDR, IP + mask, or bare IP and convert them all to network address, subnet mask, usable range, and host count in one click.
IP Allocation Planner
Free IP allocation planner: assign CIDR blocks inside a supernet to sites, VLANs, or teams and see used, free, and overlapping address space instantly.