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Lash Maths

To volume lash safely and effectively we need to know equivalent volumes between diameters. As always, it is imperative that you are not creating lash fans that are too heavy for the natural lashes to support. 

So how do we work out equivalent volumes?


To work out how many lashes we can put in a fan we must use the mathematical equation for the volume of a cone.

Volume of a cone

Volume of 0.07 12mm cone

=1/3 (3.14 x 0.035 x 12)


In Mathematics Pi =3.14

The Radius is half of the lash diameter

The height is the lash length

Volume of 0.15 12mm cone

=1/3 (3.14 x 0.075 x 12)


So let's start by working out the Volume of a 12mm 0.15 lash (assuming that this can be safely applied to the natural lash). Our equation would be:

Then let's work out the volume of one 0.07 lash

Now, to find out the equivalent volume we must divide the 0.15 volume by the 0.07 volume

0.07 diameter   0.071/0.015 = 4.6

So now we know that 4.6 0.07 volume lashes are the equivalent of one 0.15 lash. If we err on on the side of caution to protect lash health then we can say that a 4D 0.07 fan is it's equivalent.

Using this equation in the same way we can then work out how many lashes we can put in different diameter fans.

0.06 diameter      0.071/0.011 = 6.5

0.05 diameter      0.071/0.008 = 8.8 

0.04 diameter      0.071/0.005 = 14.2 

0.03 diameter      0.071/0.003 = 23.6