Formula
Address integer = octets packed into 32 bits. Mask = first prefix bits set to 1. Network = address AND mask. Broadcast = network OR inverted mask. Usable hosts = 2^(32 − prefix) − 2 for ordinary prefixes.
Developer & IT
Subnet Calculator
Calculate IPv4 network address, broadcast address, usable host range, wildcard mask and host count from an IP address and CIDR prefix.
Developer & IT
Subnet Calculator
Live answer192.168.10.0/24Mask 255.255.255.0 · wildcard 0.0.0.255 · broadcast 192.168.10.255 · usable range 192.168.10.1 to 192.168.10.254 · 254 usable host address(es)
Live result192.168.10.0/24Mask 255.255.255.0 · wildcard 0.0.0.255 · broadcast 192.168.10.255 · usable range 192.168.10.1 to 192.168.10.254 · 254 usable host address(es)
Formula used
Address integer = octets packed into 32 bits. Mask = first prefix bits set to 1. Network = address AND mask. Broadcast = network OR inverted mask. Usable hosts = 2^(32 − prefix) − 2 for ordinary prefixes.
This is the method behind the answer, so the result can be checked rather than simply trusted.Visual grid
This number is one point on a larger pattern
Subnet is not just a final answer. It is a step on a line: before and after, input and output, assumption and result.
Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars
InputFormulaResult
192.168.10.0/24CalculationTime keeps the path visible: the input, the method and the final number belong together.
CalculationTime
Subnet Calculation Report
192.168.10.0/24Mask 255.255.255.0 · wildcard 0.0.0.255 · broadcast 192.168.10.255 · usable range 192.168.10.1 to 192.168.10.254 · 254 usable host address(es)
Inputs
- IP octet 1
- 192
- IP octet 2
- 168
- IP octet 3
- 10
- IP octet 4
- 25
- CIDR prefix
- 24 /n
Method
Address integer = octets packed into 32 bits. Mask = first prefix bits set to 1. Network = address AND mask. Broadcast = network OR inverted mask. Usable hosts = 2^(32 − prefix) − 2 for ordinary prefixes.
- 192.168.10.25/24 has mask 255.255.255.0, network 192.168.10.0, broadcast 192.168.10.255 and ordinary usable host range 192.168.10.1 to 192.168.10.254.
Assumptions
- IPv4 only; IPv6 is not modelled.
- /31 and /32 networks have special point-to-point or host-route behaviour, so usable host notes differ.
- Routing policy, VLANs, NAT, DHCP scopes and firewall rules are outside the arithmetic.
Notes
Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.
Worked example
192.168.10.25/24 has mask 255.255.255.0, network 192.168.10.0, broadcast 192.168.10.255 and ordinary usable host range 192.168.10.1 to 192.168.10.254.
Professional note
Master’s Tip: print the wildcard mask beside the subnet mask when handing a network note to someone writing ACLs.
Regional and unit assumptions
Standard IPv4 CIDR arithmetic using 32-bit addresses and binary masks.
Assumptions and limitations
- IPv4 only; IPv6 is not modelled.
- /31 and /32 networks have special point-to-point or host-route behaviour, so usable host notes differ.
- Routing policy, VLANs, NAT, DHCP scopes and firewall rules are outside the arithmetic.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Address integer = octets packed into 32 bits. Mask = first prefix bits set to 1. Network = address AND mask. Broadcast = network OR inverted mask. Usable hosts = 2^(32 − prefix) − 2 for ordinary prefixes.
Standard or basis
Standard IPv4 CIDR arithmetic using 32-bit addresses and binary masks.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: print the wildcard mask beside the subnet mask when handing a network note to someone writing ACLs.
Related calculators
Questions
What does /24 mean?
/24 means the first 24 bits are the network prefix, leaving 8 host bits.
How many hosts are in a /24?
An ordinary /24 has 256 addresses and usually 254 usable host addresses after network and broadcast.
Does this support IPv6?
No. This page is deliberately IPv4-only.
Calculation note
CIDR made IPv4 subnetting more flexible by allowing arbitrary prefix lengths instead of fixed classful networks.
Sources and further readingIETF RFC 4632 — Classless Inter-domain Routing