Linux & Unix Calculators
File systems, storage, memory, CPU, processes, permissions, security and system administration.
Tools for working with Linux and Unix systems: file permission modes, disk and inode usage, memory and swap sizing, CPU utilisation from /proc counters and similar sysadmin arithmetic. The pages explain where each input comes from on a real system, so you know which command to run to get it.
Results describe the numbers you enter. Kernel versions, filesystems and distributions differ in defaults and reserved space, so check a figure against your own machine before acting on it.
233 of 233 available now
- CPU Utilization CalculatorCalculate CPU utilization percentage from user, system and idle time measurements.
- Load Average CalculatorInterpret 1, 5 and 15-minute load averages relative to available CPU cores.
- CPU Core Requirement CalculatorCalculate the number of CPU cores needed to handle a target workload and concurrency.
- CPU Frequency CalculatorCalculate effective CPU clock frequency accounting for turbo boost and throttling.
- CPU Bottleneck CalculatorIdentify whether CPU is the limiting resource by comparing load, wait and I/O metrics.
- CPU Scheduling CalculatorCalculate process scheduling time slices under the Linux CFS scheduler.
- Context Switch CalculatorEstimate context switch overhead and its impact on effective CPU throughput.
- Interrupt Rate CalculatorCalculate hardware interrupt rate per second and its CPU overhead impact.
- System Load CalculatorCalculate overall system load combining CPU, I/O wait and runnable process counts.
- Thread Count CalculatorCalculate optimal thread count for a workload based on core count and I/O wait ratio.
- Process Count CalculatorCalculate maximum concurrent processes supportable given CPU and memory constraints.
- CPU Affinity CalculatorCalculate CPU affinity masks for pinning processes to specific cores with taskset.
File System
All 20 File System calculators →- File Size CalculatorConvert file sizes between bytes, KB, MB, GB and TB with binary or decimal units.
- Directory Size CalculatorEstimate total directory size from file counts and average file sizes.
- Disk Usage CalculatorCalculate used, free and total disk space percentages for a Linux filesystem.
- Filesystem Utilization CalculatorDetermine filesystem capacity utilization and headroom before hitting full disk alerts.
- Inode Usage CalculatorCalculate inode consumption and remaining inode capacity on an ext4 or xfs filesystem.
- Block Size CalculatorCalculate the number of disk blocks required to store a file given the filesystem block size.
- Filesystem Overhead CalculatorEstimate metadata and journaling overhead a filesystem subtracts from raw partition capacity.
- Mount Point Capacity CalculatorCalculate available capacity across multiple mount points sharing an underlying volume.
- Disk Growth EstimatorProject when a disk volume will run out of space based on its current growth rate.
- Partition Size PlannerPlan partition sizes for root, home, var and swap based on total disk capacity.
- Swap Size CalculatorRecommend swap partition or swap file size based on installed RAM and workload type.
- Filesystem Resize CalculatorCalculate new usable capacity after growing or shrinking a filesystem or partition.
Linux & System Administration
All 73 Linux & System Administration calculators →- File Permission (chmod) CalculatorWork out file permission (chmod) instantly with clear inputs, formula shown and shareable results.
- Octal Permission Converter CalculatorWork out octal permission converter instantly with clear inputs, formula shown and shareable results.
- umask Value CalculatorWork out umask value instantly with clear inputs, formula shown and shareable results.
- SUID SGID Sticky Bit CalculatorWork out suid sgid sticky bit instantly with clear inputs, formula shown and shareable results.
- Filesystem Inode Requirement CalculatorWork out filesystem inode requirement instantly with clear inputs, formula shown and shareable results.
- Block Size Overhead CalculatorWork out block size overhead instantly with clear inputs, formula shown and shareable results.
- Partition Size Plan CalculatorWork out partition size plan instantly with clear inputs, formula shown and shareable results.
- LVM Sizing CalculatorWork out lvm sizing instantly with clear inputs, formula shown and shareable results.
- Tmpfs Sizing CalculatorWork out tmpfs sizing instantly with clear inputs, formula shown and shareable results.
- RAID Rebuild Time CalculatorWork out raid rebuild time instantly with clear inputs, formula shown and shareable results.
- RAID Failure Probability CalculatorWork out raid failure probability instantly with clear inputs, formula shown and shareable results.
- Disk IOPS From Spindles CalculatorWork out disk iops from spindles instantly with clear inputs, formula shown and shareable results.
- RAM Usage CalculatorCalculate used, free and cached RAM percentages from free command output values.
- Memory Utilization CalculatorCalculate overall memory utilization percentage across physical RAM and swap.
- Swap Utilization CalculatorCalculate swap space usage percentage and estimate performance impact of swapping.
- Page Cache CalculatorCalculate the portion of RAM used as page cache and its effect on available memory.
- Buffer Cache CalculatorEstimate buffer cache size used for block device I/O buffering on Linux systems.
- Shared Memory CalculatorCalculate System V or POSIX shared memory segment size requirements for applications.
- HugePages CalculatorCalculate the number of HugePages needed to back a given amount of application memory.
- Kernel Memory CalculatorEstimate kernel memory footprint including slab allocations and kernel structures.
- Memory Leak EstimatorEstimate time until out-of-memory based on observed process memory leak rate.
- OOM Killer Threshold CalculatorCalculate the memory threshold at which the Linux OOM killer is likely to trigger.
- NUMA Memory PlannerPlan memory allocation across NUMA nodes to minimize remote memory access latency.
- Virtual Memory CalculatorCalculate virtual address space size and mapping requirements for a process.
Networking
All 20 Networking calculators →- Socket Count CalculatorCalculate maximum concurrent socket connections supportable by system file descriptor limits.
- TCP Connection CalculatorCalculate maximum concurrent TCP connections a server can handle given port and memory limits.
- UDP Port CalculatorCalculate available UDP port range and usable ports after reserved and ephemeral ranges.
- Network Buffer Size CalculatorCalculate optimal socket send/receive buffer sizes based on bandwidth and latency.
- MTU CalculatorCalculate maximum transmission unit and payload size after protocol header overhead.
- MSS CalculatorCalculate maximum segment size from MTU by subtracting TCP/IP header overhead.
- TCP Window Size CalculatorCalculate optimal TCP window size from bandwidth-delay product for maximum throughput.
- Bandwidth Utilization CalculatorCalculate network bandwidth utilization percentage against interface link capacity.
- Packet Rate CalculatorCalculate packets-per-second rate and its CPU load impact on network interrupt handling.
- NIC Throughput CalculatorCalculate achievable throughput of a network interface card given link speed and overhead.
- Interface Queue CalculatorCalculate network interface queue length needed to avoid packet drops under burst load.
- Bonding Capacity CalculatorCalculate aggregate bandwidth capacity of a bonded network interface across multiple NICs.
Processes
All 20 Processes calculators →- PID Range CalculatorCalculate PID exhaustion risk from pid_max and current process creation rate.
- Zombie Process RatioCalculate the ratio of zombie processes to total processes on a running system.
- Fork Rate CalculatorCalculate process fork rate per second and its impact on system overhead.
- Process Lifetime CalculatorCalculate average process lifetime and turnover rate from start and end timestamps.
- Cron Schedule CalculatorParse and explain a cron expression, showing the resulting execution schedule.
- Cron Next Run CalculatorCalculate the next several run times for a given cron expression and timezone.
- at Job Scheduler CalculatorCalculate the exact execution time for a one-off job scheduled with the at command.
- systemd Service Dependency CalculatorCalculate systemd unit startup order and dependency chain resolution time.
- Service Restart Delay CalculatorCalculate cumulative restart delay for a systemd service using exponential backoff.
- Daemon Count CalculatorCalculate the number of background daemons running and their aggregate resource usage.
- Open File Descriptor CalculatorCalculate open file descriptor usage against system and per-process ulimit thresholds.
- ulimit CalculatorCalculate recommended ulimit values for file descriptors, processes and memory.
Security
All 20 Security calculators →- File Permission CalculatorConvert Linux file permissions between octal, symbolic and chmod notation instantly.
- Octal Permission CalculatorConvert numeric octal permission codes like 755 or 644 into readable rwx notation.
- Symbolic Permission CalculatorConvert symbolic permission strings like rwxr-xr-- into octal chmod values.
- SUID CalculatorCalculate the resulting permission bits and security implications of setting the SUID bit.
- SGID CalculatorCalculate the resulting permission bits and behavior of setting the SGID bit on files or directories.
- Sticky Bit CalculatorCalculate the resulting permission bits of setting the sticky bit on shared directories.
- ACL Permission CalculatorCalculate effective access permissions when POSIX ACLs override standard file mode bits.
- SELinux Context CalculatorDecode SELinux security context labels into user, role, type and sensitivity components.
- AppArmor Profile CalculatorEstimate AppArmor profile rule coverage and enforcement mode impact on an application.
- SSH Key Length CalculatorCompare SSH key algorithm and bit-length strength across RSA, ECDSA and Ed25519.
- SSH Connection Capacity CalculatorCalculate maximum concurrent SSH sessions supportable under sshd MaxSessions and MaxStartups.
- SSH Session Timeout CalculatorCalculate SSH idle session timeout from ClientAliveInterval and ClientAliveCountMax settings.
Storage
All 20 Storage calculators →- LVM PV Size CalculatorCalculate LVM physical volume size and metadata overhead for a given block device.
- LVM VG Capacity CalculatorCalculate total volume group capacity from combined physical volume extents.
- LVM LV Size CalculatorCalculate logical volume size allocation from available volume group extents.
- LVM Snapshot Size CalculatorSize an LVM snapshot volume based on expected change rate and snapshot lifetime.
- RAID 0 Capacity CalculatorCalculate total usable capacity and performance of a RAID 0 striped array.
- RAID 1 Capacity CalculatorCalculate usable capacity of a RAID 1 mirrored array from disk count and size.
- RAID 5 Capacity CalculatorCalculate usable capacity of a RAID 5 array accounting for single-disk parity.
- RAID 6 Capacity CalculatorCalculate usable capacity of a RAID 6 array accounting for dual-disk parity.
- RAID 10 Capacity CalculatorCalculate usable capacity of a RAID 10 striped-mirror array from disk count and size.
- RAID Performance CalculatorEstimate combined read and write IOPS across a RAID array based on level and disk count.
- Disk IOPS CalculatorCalculate achievable disk IOPS from rotational speed, seek time and queue depth.
- Disk Throughput CalculatorCalculate sequential read/write throughput in MB/s from block size and IOPS.
System Administration
All 20 System Administration calculators →- Boot Time CalculatorBreak down system boot time across firmware, kernel and systemd unit startup phases.
- Kernel Parameter CalculatorCalculate recommended sysctl kernel parameter values for a given workload profile.
- Kernel Thread CalculatorCalculate the number of kernel threads spawned per CPU core for common kernel subsystems.
- Module Dependency CalculatorCalculate kernel module load order and dependency depth from modinfo dependency chains.
- Package Dependency CalculatorCalculate total download size and install order for a package and its dependency tree.
- Repository Mirror CalculatorCalculate storage and bandwidth needed to host a local mirror of a package repository.
- YUM DNF Cache CalculatorCalculate disk space consumed by the YUM or DNF package manager metadata and RPM cache.
- APT Cache CalculatorCalculate disk space consumed by the APT package cache and downloaded .deb archives.
- Package Size CalculatorEstimate installed size versus download size for a software package and its dependencies.
- Update Time EstimatorEstimate total time to download and install a batch of system package updates.
- Patch Window CalculatorCalculate the maintenance window duration needed to patch a fleet of servers safely.
- Reboot Duration CalculatorEstimate total server downtime from shutdown, POST, kernel boot and service startup phases.