ChmodCalc
Open calculator

Unix mode utility

Convert octal permissions to ls-style text

Enter three or four octal digits from 0000 through 7777 and inspect owner, group, other and special bits.

Live converter

Octal ↔ ls-style permissions

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Exactly 3 or 4 digits from 0 to 7; 755 is normalized to 0755.

Exactly 9 characters, or 10 with only - or d as the type prefix.

Owner, group and other bits

ReadWriteExecute/searchOwner
Group
Others

Special bits

Special letters share the execute positions: s/S for owner or group and t/T for others.

Display context

The leading type character is display context and is not part of the numeric mode mask.

ChmodCalc represents the traditional Unix mode-bit mask. It does not evaluate ACLs, umask, ownership, symlinks, recursive traversal or the suitability of a mode for a particular system.

GNU chmod nuance: on directories, plain 3/4-digit numeric modes can preserve existing setuid/setgid bits in some command forms. This calculator shows the requested bit mask, not guaranteed post-command filesystem state.

Current valid mask

Converted permission mode

Four-digit octal mask0755
9-character ls-style permissionsrwxr-xr-x

Every bit explained

BitClassOctal valueState
ReadOwner0400On
WriteOwner0200On
Execute/searchOwner0100On
ReadGroup0040On
WriteGroup0020Off
Execute/searchGroup0010On
ReadOthers0004On
WriteOthers0002Off
Execute/searchOthers0001On
setuidSpecial4000Off
setgidSpecial2000Off
Sticky bitSpecial1000Off

Curated modes

Common permission masks

These presets are examples, not universal security recommendations. File type, ownership, application and deployment context determine whether a mode is appropriate.