【Blender】How to Fix Mirror Modifier Not Working Symmetrically

Problem

After applying the Mirror Modifier, the object isn't being duplicated symmetrically (left-right or top-bottom).

Causes and Solutions

Cause 1: Object Origin Position

The Mirror Modifier creates a mirrored copy around the object's origin (the orange dot).

If the origin is at the center of the object, the mirrored copy overlaps in place, making the mirror effect invisible.

Solution: Move the Origin

Move the origin to the world center (0,0,0) or another appropriate point, and the object will mirror correctly around that axis.

1. Place the 3D Cursor at World Origin

   • Press Shift + C (moves the 3D cursor to position 0,0,0)

2. Make Sure You're in Object Mode

   • If in Edit Mode, press Tab to switch to Object Mode

3. Move Origin to 3D Cursor Position

   • With the object selected, right-click
   • Select Set Origin → Origin to 3D Cursor

The origin will now be at the world center, and the Mirror Modifier will work correctly.

Cause 2: Unapplied Transforms

If the mirror is still offset after setting the origin correctly, the object's transforms (scale/rotation) may not be applied.

Check the Scale values in the sidebar (N key) under the "Transform" panel. If Scale is anything other than 1.000, the mirror position will be offset.

Solution: Apply Transforms

1. Select the object in Object Mode
2. Press Ctrl + A
3. Select "All Transforms"

This resets Scale to 1.000, and the mirror will work correctly.

Additional Notes

• Origin: The reference point for an object. Acts as the center for translation, rotation, and scale operations
• 3D Cursor: A tool in Blender used to specify positions
• You can change the mirror axis (X/Y/Z) in the modifier properties as needed