What Chmod Calculator helps you do

Build Linux and Unix file permissions for owner, group and others, then read the octal mode, the symbolic string and a ready-to-copy chmod command. You can start from a common preset or choose a digit for each class. The tool covers the standard nine permission bits and nothing beyond them.

The calculation runs in your browser with no server request to Haivix.

How it works

Most tools here are offline calculators: the address math, RAID capacity, permission bits, TCP window sizing and transfer-time estimate all run in your browser with no request. The RDAP lookup is the exception, because registration data lives in public registries and the domain must be sent to a lookup service. Unit conventions matter throughout: a megabyte may mean 1,000,000 or 1,048,576 bytes, and a megabit is always one eighth of a megabyte. These are reference models, not live checks, so a port can be listed without a service running, a permission mode can be valid without being appropriate, and a RAID estimate can differ from formatted capacity.

How to use Chmod Calculator

Pick a preset, or set the owner, group and others digits.
Read the octal mode and symbolic string.
Check the meaning of each class before applying it.
Copy the chmod command and run it on the target.

When to use it

Work out the chmod value for a script or directory.
Check what a permission mode actually allows.
Translate an ls -l permission string into octal.
Verify a deployment script's file modes.
Set a readable file without making it executable.
Compare the exposure of 755 and 775.

When not to use it

Do not use it for setuid, setgid or sticky bits; those need a fourth digit.
Do not use it for ACLs or platform-specific permission models.
Do not assume a mode is safe without considering ownership and context.

Example

Owner read, write and execute plus group and others read and execute gives 755 and rwxr-xr-x. A regular file that only the owner may read and write is 600. Adding group write to 755 gives 775, which lets the group modify the file or directory.

What you can do with Chmod Calculator

Choose presets such as 755, 644, 700, 600 or 775.
Set a digit from 0 to 7 for owner, group and others.
Show the nine-character symbolic form.
Generate a chmod command.
Switch a custom mode back to a matching preset.
Copy the command locally.

Example: check the model against the live system

Note the unit convention before comparing figures. Mbps and MB/s differ by a factor of eight, and MB and MiB differ by about 5 percent.

Treat a lookup as a starting point. A port reference, a permission mode and a RAID calculation all describe expectations, not the state of a running host.

Confirm on the system itself where it matters: ss or netstat for listeners, ls -l for permissions, the controller utility for array status.

Keep RAID in perspective. It protects against a disk failure, not against deletion, corruption, ransomware or a lost site.

Record the inputs alongside the result so a later comparison uses the same assumptions.

Check the time unit on latency. A round-trip time is usually milliseconds, and entering seconds changes the bandwidth-delay product by a factor of a thousand.

Treat registry data as a snapshot. RDAP records can be redacted, cached or updated after a transfer, so confirm ownership and expiry with the registrar.

What to know before you start

It shows the standard nine permission bits and not special bits such as setuid or sticky.
Correct permissions still depend on ownership and context, which the calculator cannot judge.
It does not model ACLs, SELinux labels or umask.
The generated command uses a placeholder filename.

Common mistakes

Using 777 for convenience and granting write access to everyone.
Applying a file mode to a directory without execute permission.
Forgetting the leading zero when a fourth digit is needed elsewhere.
Assuming the mode alone controls access; ownership still matters.

Troubleshooting

If a digit is rejected, it must be between 0 and 7.

If the preset switches to custom, the current combination has no preset.

If a script will not run, the execute bit may be missing.

If a directory cannot be entered, execute permission may be missing.

Chmod Calculator