Calculating hydration percentage of sourdough starter

I was asked by a member in facebook group Thermomix Fervent Thermist in a post when I posted up my sourdough bread Thermomix recipe, can't remember which recipe it was, the member asked me about what percentage is my sourdough starter..... frankly speaking, I have no idea of what she meant, not until I searched for the word "hydration percentage" of sourdough starter.

After finished reading two articles, I still don't quite get what they meant about 1 cup of flour 1/4 cup of water.... and how this percentage come out of.

Well today, I put into action, read a few more posts about percentage of hydration level of a sourdough starter. Many still explained in cups and pounds, when I started making sourdough was all about grams, and now a Thermomix user, in grams too.

Not that hard to understand though, just need a little time to figure it out the formula laaah!

Here it is, how to calculate the percentage [Y%] of hydration level of your sourdough starter by grams.

Use a calculator to help you key in:
[Amount of water] divide [Amount of flour] = Z

THEN

Z x 100 = Y% [percentage of the hydration level]

So what is the hydration percentage for the sourdough I am using?

Joyful Jane sourdough starter is being fed each time with 30g of water, 50g of flour:
using a calculator to help you key in:

30 ÷ 50 = 0.6

0.6 x 100 = 60

hence the answer is  60% hydration

According to

Bakers percentage/hydration simple percentage volumetric equivalence chart

For 60% hydration sourdough starter, the measurement of solid ingredients will be
60% Hydration Sourdough Starter | 63% Flour | 38% Water | 4 cups of flour |1.5 cup of water