Subnet details
Field Value Type
No subnet details were returned.
Subnet Calculator
Calculate IPv4 subnet boundaries and host ranges.
Use the Subnet Calculator to turn an IPv4 address and CIDR prefix into the real network range, usable hosts, netmask, wildcard mask, and address counts before moving to the next network or routing step.
Check the subnet math first when a route, firewall rule, or host range looks wrong.
Calculation result
192.168.1.10/24
VALID SUBNET
Address counts
Field Value Scope
No address counts were returned.
What this Subnet Calculator does
This Subnet Calculator computes the IPv4 network, broadcast, first and last usable host, netmask, wildcard mask, and address counts for a given IP and prefix length.
Use it to verify CIDR math, confirm host ranges, and check whether a route or firewall definition matches the subnet you actually intended.
It does not validate live reachability or routing by itself. If the math looks correct, move next to Ping, Traceroute, or IP Lookup for operational checks.
When to use this tool
You need the network, broadcast, and host range for an IPv4 subnet.
A server or firewall rule needs to be checked against the actual subnet boundaries.
You want to confirm the usable host range for a CIDR block before allocating addresses.
A route or ACL uses CIDR notation and you want to understand the real address span quickly.
You are troubleshooting overlapping subnets, wrong masks, or address-assignment mistakes.
You need a quick IP math check before moving to Ping, Traceroute, or routing analysis.
How to use the Subnet Calculator
- Enter an IPv4 address and prefix, or paste a combined CIDR value.
- Run the calculation and review the network, broadcast, and host range.
- Check the netmask and wildcard mask against the config you expected.
- Compare the calculated range with your route, ACL, or address-allocation plan.
- If the math looks right but the network still fails, continue to Ping, Traceroute, or IP Lookup next.
How to interpret subnet results
Valid subnet calculated
Likely meaning: The IP and prefix produced a valid IPv4 subnet result.
Common causes: The input is well-formed and the calculator could derive the subnet boundaries and host counts.
Next action: Use the network, netmask, and host range in your next routing, firewall, or address-planning step.
Very small subnet
Likely meaning: The prefix leaves few or no traditional host addresses, such as /31 or /32.
Common causes: Point-to-point or host-specific addressing often uses these masks intentionally.
Next action: Confirm whether the subnet is intended for a single host or point-to-point link before assuming it is wrong.
Unexpected host range
Likely meaning: The network or broadcast boundaries do not match what you expected.
Common causes: Wrong prefix length, wrong base IP, or copied CIDR values are common causes.
Next action: Double-check the intended mask and source IP, then compare the calculated network with your routing or firewall config.
Invalid input
Likely meaning: The IPv4 address or prefix is not valid for subnet calculation.
Common causes: Typos, missing octets, or prefixes outside /0 to /32 are the usual reasons.
Next action: Enter a valid IPv4 address and prefix, or paste a full CIDR like 192.168.1.10/24.
Common subnet issues this tool helps uncover
Wrong CIDR mask applied to a server or interface
Firewall or route definitions using the wrong subnet boundary
Overlapping or unexpectedly broad private ranges
Broadcast or usable-host expectations that do not match the actual mask
Point-to-point links using /31 or /32 when a larger subnet was assumed
The right IP is present, but the wrong prefix causes path or ACL problems
Next steps after subnet calculation
Check IP Lookup
If you want public owner, ASN, or reverse-DNS context for an address inside the subnet, continue to IP Lookup.
Run Ping
If the subnet math looks right, check whether a specific host in the range looks reachable.
Run Traceroute
If the addressing looks correct but traffic still fails, continue to route preflight and path analysis.
Check ASN Lookup
For public ranges, move to ASN Lookup to understand the network operator and prefix ownership.
Related tools
IP Lookup
Inspect basic ownership, reverse DNS, and network details for an IP.
ASN Lookup
Look up AS numbers, prefixes, and operator ownership details.
Ping
Check whether a host responds and measure round-trip latency.
Traceroute
Trace the network path between a client and destination host.
DNS Lookup
Query A, AAAA, CNAME, TXT, and other DNS records for a domain.
Subnet Calculator FAQ
What does the Subnet Calculator do?
It calculates the IPv4 network address, broadcast address, netmask, wildcard mask, first and last usable hosts, and address counts for a given IP and prefix.
What input should I enter?
Enter an IPv4 address and a CIDR prefix like /24, or paste a combined value like 192.168.1.10/24.
Can I use this for IPv6?
This starter calculator is focused on IPv4 subnet math. It does not currently calculate IPv6 ranges.
Why do /31 and /32 look different?
These masks leave very few addresses and are often used for point-to-point links or single hosts, so traditional network, broadcast, and usable-host assumptions change.
What should I check after subnet calculation?
Usually Ping, Traceroute, IP Lookup, or ASN Lookup depending on whether you are validating private addressing, public routes, or destination reachability.
Why does the network range not match what I expected?
The prefix length may be wrong, the IP may belong to a different block than you assumed, or the subnet may be broader or narrower than intended.