Subnet calculator
Use an IPv4 address and CIDR prefix to find its network, usable hosts, broadcast address, and masks.
Free IPv4 and IPv6 utility
IPv4 & IPv6 Subnet Calculator
Calculate an IPv4 or IPv6 network from an address and prefix, or generate a custom IPv4 start-to-end address list.
Your addresses are processed locally in your browser and are not sent to DevsLoad.
How it works
Calculate an IPv4 subnet in three steps
- 01
Enter an IP address
Provide any IPv4 address inside the subnet, such as 43.250.157.66.
- 02
Choose the CIDR prefix
Select a prefix such as /30. The calculator finds the network boundary automatically.
- 03
Review the subnet
See the usable host range, broadcast address, masks, host counts, and complete address list when practical.
Calculation modes
Calculate a subnet or define a custom range
Custom address range
Switch modes when you need every IPv4 address between two explicit endpoints.
Safe browser output
Ranges are limited to 10,000 addresses so large inputs cannot overwhelm your browser.
Are the start and end IP addresses included?
Yes. The generated list is inclusive, so it contains both the start and end address.
Do I need to know the end address?
No. In Subnet Calculator mode, enter one IP address and select its CIDR prefix. The tool calculates the network, usable range, and broadcast address.
Does CIDR output include network and broadcast addresses?
Yes. The tool lists the complete address block. You can remove reserved addresses if your specific network workflow requires usable host addresses only.
Is my IP range uploaded?
No. Validation and generation happen locally in your browser.