Today is is 6-12.Same here. I have a digital scale and found it pretty close but never calibrated. the mechanical scale, if kept clean, should be close to full proof.
For 6-12, L =6, M =3, S =2 for a total of 11. 3 Lg whites.
6-13, L =2, M =9, S =4 & P =1 for a total of 16 (good day!). 2 Lg & 5 M whites.
This means the former broody, whose face turned red again, is laying.