# Scale by Volume of Object in Blender

I have two skulls like so:

Using the 3D print addon toolbox, I know the volumes of each:

• 747735056401 for the larger one
• 569718590290 For the smaller one

I'd like to scale the smaller one to be the same volume as the larger one. Not being a math wiz, I simply did: 747735056401/569718590290= 1.312464, so I hit S and typed in 1.312464.

But, I didn't even realize that would just scale the x,y,z dimensions and all of a sudden my new volume had gone way up to 12880819961337. Way larger than intended.

Does anyone either know (through a Blender command, or through better math understanding) how I could scale the volume of one to be the same as the other?

The volume is proportional to the cube of the scale. For example, doubling all of the dimensions would result in a volume that is 2x2x2 = 8 times the volume.

Therefore, in order to scale the volume by 1.312464 you have to scale each dimension by the cube root of 1.312464. ie, approximately 1.0948678.

• This probably falls into "I should have googled this" but thank you! Commented Jan 29, 2021 at 20:00
• No worries. Actually, you can get Blender to do the maths for you also - since you can type equations into fields and operators. Simply select the object and type s1.312464***0.333333<Enter> and Blender should scale it for you. Here the S is for Scale, the numbers enter the scale, the first * seems to be necessary to end the number (don’t know why) then ** is the power operation and 0.333333 is 1/3 (or near enough) for cube root. Commented Jan 29, 2021 at 20:35
• That's odd.. I have no problem with 2**.333 , 2**0.333, 2**(1/3) ... Linux 291 Commented Jan 30, 2021 at 4:55
• Thanks for the feedback @RobinBetts. I’ve tried this on two Windows 10 systems (one with Blender 2.91 and the other 2.83.6) and both are needing three *s for this to work. Very strange indeed. Commented Jan 30, 2021 at 7:48