How to change default scale of the added objects?

Question

I noticed that when I add new object it is very tiny compared to existing objects. In the example on the photo it is 10 times smaller.

Viewport scale is 0.001

What is the problem?

Answer 1

The default Viewport Scale in Blender is and should be 1 (not 0.001). Reasons follow. There are legitimate reasons to reset the Viewport Scale to something much larger or smaller, but unless you don't have or know these reasons, it should not be altered, otherwise you might experience some serious strange behaviour.

Understanding Viewport Scale

In Blender, the default unit of the standard cube is 1 meter. Since the default cube has an extent of 1 meter in all directions, positive and negative, the edge length of the default cube is 2 meters.

If you want to create scenes in Blender whose scales are significantly larger or smaller than in the normal world, then it is recommended to adjust the Viewort Scale. This is because this scale is used as a reference for many aspects of the Blender environment, including physics simulations, rendering settings, camera phsysics (i.e. optics), and real-world scale modeling. Again, having "things" in the wrong scale may cause problems, or otherwise: If you try to scale your micro-world into the standard 1-meter world, you will have to account for a whole bunch of other things to "get right", which could resolve quite easily if you instead had chosen the correct scale of your world.

This Viewport Scale is by default 1. When you import or add objects into Blender with a "strange" Viewport Scale, they may appear much smaller or larger because they are typically created with real-world measurements in mind.

Fix

Problem in a certain .blend file

Your problem may be a problem in one certain scene - you or someone accidentally or intentional changed the Viewport Scale (for what reason ever). If this intention is valid, then stay with it - the benefits may be worth the mentioned sideeffects. If it's unintentional - go change it back to normal! If this behavior occurs even in new scenes, then you might unintentionally have changed the default scene of Blender.

Problem occurs in all new created .blend files

You have accidentially changed the default settings in the startup file.

You have two choices:

1. In File => Defaults you can select Load Factory Settings. This will reset all your default settings, you may loose settings th tyou changed intentionally.
2. Or you go to File => New => General (= loading your customized Default scene), change the Viewport Scalevalue back to 1, then got to File => Defaults => Save Startup File, which will write your customized settings with the standard Viewport Scale into your startup File.