diff --git a/src/tools/chmod-calculator/chmod-calculator.service.test.ts b/src/tools/chmod-calculator/chmod-calculator.service.test.ts
index a7f94ca8..1a994de8 100644
--- a/src/tools/chmod-calculator/chmod-calculator.service.test.ts
+++ b/src/tools/chmod-calculator/chmod-calculator.service.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { computeChmodOctalRepresentation, computeChmodSymbolicRepresentation, computePermissionsFromChmodOctalRepresentation, computePermissionsFromChmodSymbolicRepresentation } from './chmod-calculator.service';
+import { computeChmodOctalRepresentation, computeChmodSymbolicRepresentation, computePermissionsFromChmodOctalRepresentation, computePermissionsFromChmodSymbolicRepresentation, computeUmaskRepresentation } from './chmod-calculator.service';
 
 describe('chmod-calculator', () => {
   describe('computeChmodOctalRepresentation', () => {
@@ -454,4 +454,106 @@ describe('chmod-calculator', () => {
       });
     });
   });
+
+  describe('computeUmaskRepresentation', () => {
+    it('get the umask from permissions', () => {
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: true, write: true, execute: true },
+            group: { read: true, write: true, execute: true },
+            public: { read: true, write: true, execute: true },
+            flags: { setuid: false, setgid: false, stickybit: false },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '000',
+        symbolic: 'umask u=rwx,g=rwx,o=rwx',
+      });
+
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: false, write: false, execute: false },
+            group: { read: false, write: false, execute: false },
+            public: { read: false, write: false, execute: false },
+            flags: { setuid: false, setgid: false, stickybit: false },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '777',
+        symbolic: 'umask u=,g=,o=',
+      });
+
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: false, write: true, execute: false },
+            group: { read: false, write: true, execute: true },
+            public: { read: true, write: false, execute: true },
+            flags: { setuid: false, setgid: false, stickybit: false },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '542',
+        symbolic: 'umask u=w,g=wx,o=rx',
+      });
+
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: true, write: false, execute: false },
+            group: { read: false, write: true, execute: false },
+            public: { read: false, write: false, execute: true },
+            flags: { setuid: false, setgid: false, stickybit: false },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '356',
+        symbolic: 'umask u=r,g=w,o=x',
+      });
+
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: false, write: false, execute: true },
+            group: { read: false, write: true, execute: false },
+            public: { read: true, write: false, execute: false },
+            flags: { setuid: false, setgid: false, stickybit: false },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '653',
+        symbolic: 'umask u=x,g=w,o=r',
+      });
+
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: false, write: true, execute: false },
+            group: { read: false, write: true, execute: false },
+            public: { read: false, write: true, execute: false },
+            flags: { setuid: false, setgid: false, stickybit: false },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '555',
+        symbolic: 'umask u=w,g=w,o=w',
+      });
+
+      expect(
+        computeUmaskRepresentation({
+          permissions: {
+            owner: { read: false, write: false, execute: true },
+            group: { read: false, write: true, execute: false },
+            public: { read: true, write: false, execute: false },
+            flags: { setuid: true, setgid: true, stickybit: true },
+          },
+        }),
+      ).to.deep.eq({
+        octal: '653',
+        symbolic: 'umask u=x,g=w,o=r',
+      });
+    });
+  });
 });
diff --git a/src/tools/chmod-calculator/chmod-calculator.service.ts b/src/tools/chmod-calculator/chmod-calculator.service.ts
index 9a1ced4c..e8a069f6 100644
--- a/src/tools/chmod-calculator/chmod-calculator.service.ts
+++ b/src/tools/chmod-calculator/chmod-calculator.service.ts
@@ -1,7 +1,7 @@
 import _ from 'lodash';
 import type { GroupPermissions, Permissions, SpecialPermissions } from './chmod-calculator.types';
 
-export { computeChmodOctalRepresentation, computeChmodSymbolicRepresentation, computePermissionsFromChmodOctalRepresentation, computePermissionsFromChmodSymbolicRepresentation };
+export { computeUmaskRepresentation, computeChmodOctalRepresentation, computeChmodSymbolicRepresentation, computePermissionsFromChmodOctalRepresentation, computePermissionsFromChmodSymbolicRepresentation };
 
 function computeChmodOctalRepresentation({ permissions }: { permissions: Permissions }): string {
   const permissionValue = { read: 4, write: 2, execute: 1 };
@@ -86,3 +86,30 @@ function computePermissionsFromChmodSymbolicRepresentation(symbolicPermissions:
 
   return computePermissionsFromChmodOctalRepresentation(octalString);
 }
+
+function computeUmaskRepresentation({ permissions }: { permissions: Permissions }): {
+  octal: string
+  symbolic: string
+} {
+  const permissionValue = { read: 'r', write: 'w', execute: 'x' };
+  const getGroupPermissionValue = (permission: GroupPermissions) =>
+    _.reduce(permission, (acc, isPermSet, key) => acc + ((isPermSet ? _.get(permissionValue, key, '') : '')), '');
+
+  const symbolic = `umask u=${getGroupPermissionValue(permissions.owner)},g=${getGroupPermissionValue(permissions.group)},o=${getGroupPermissionValue(permissions.public)}`;
+  const octal = (0o777 - Number.parseInt(
+    computeChmodOctalRepresentation({
+      permissions:
+      {
+        owner: permissions.owner,
+        group: permissions.group,
+        public: permissions.public,
+        flags: { setuid: false, setgid: false, stickybit: false },
+      },
+    }), 8))
+    .toString(8)
+    .padStart(3, '0');
+
+  return {
+    symbolic, octal,
+  };
+}
diff --git a/src/tools/chmod-calculator/chmod-calculator.vue b/src/tools/chmod-calculator/chmod-calculator.vue
index ed7ec9cb..502f8491 100644
--- a/src/tools/chmod-calculator/chmod-calculator.vue
+++ b/src/tools/chmod-calculator/chmod-calculator.vue
@@ -2,7 +2,7 @@
 import { useThemeVars } from 'naive-ui';
 
 import InputCopyable from '../../components/InputCopyable.vue';
-import { computeChmodOctalRepresentation, computeChmodSymbolicRepresentation, computePermissionsFromChmodOctalRepresentation, computePermissionsFromChmodSymbolicRepresentation } from './chmod-calculator.service';
+import { computeChmodOctalRepresentation, computeChmodSymbolicRepresentation, computePermissionsFromChmodOctalRepresentation, computePermissionsFromChmodSymbolicRepresentation, computeUmaskRepresentation } from './chmod-calculator.service';
 
 import type { Group, Scope } from './chmod-calculator.types';
 import { useValidation } from '@/composable/validation';
@@ -81,6 +81,7 @@ watch(
 
 const octal = computed(() => computeChmodOctalRepresentation({ permissions: permissions.value }));
 const symbolic = computed(() => computeChmodSymbolicRepresentation({ permissions: permissions.value }));
+const umask = computed(() => computeUmaskRepresentation({ permissions: permissions.value }));
 </script>
 
 <template>
@@ -155,6 +156,11 @@ const symbolic = computed(() => computeChmodSymbolicRepresentation({ permissions
     </div>
 
     <InputCopyable :value="`chmod ${octal} path`" readonly />
+
+    <c-card title="Umask">
+      <InputCopyable :value="umask.octal" readonly />
+      <InputCopyable :value="umask.symbolic" readonly />
+    </c-card>
   </div>
 </template>
 
diff --git a/src/tools/chmod-calculator/index.ts b/src/tools/chmod-calculator/index.ts
index 7d299e42..73e7d709 100644
--- a/src/tools/chmod-calculator/index.ts
+++ b/src/tools/chmod-calculator/index.ts
@@ -16,6 +16,7 @@ export const tool = defineTool({
     'recursive',
     'generator',
     'octal',
+    'umask',
   ],
   component: () => import('./chmod-calculator.vue'),
   icon: FileInvoice,