How to count Cutting Rate of Glass?

Cutting Rate refers to the qty of qualified required glass size after glass cutted before polishing.

The Formula is qualified glass with required size qty x required glass length x required glass width / raw glass sheet length / raw glass sheet width=cutting rate 

So at first, we should get a very clear understanding on the standard raw glass sheet size and how many millimetre (mm.) should leave for glass length & width when cutting:

Glass Thickness (mm)	Standar Raw Glass Sheet Size (mm)	Millimetre should leave for glass L. & W. (mm)
0.25	1000×1200	0.1-0.3
0.4	1000×1500	0.1-0.3
0.55/0.7/1.1	1244.6×1092.2	0.1-0.3
1.0/1.1	1500×1900	0.1-0.5
above 2.0	1830×2440	0.5-1.0
3.0 & above 3.0	1830×2400;2440×3660	0.5-1.0

For example:

Required Glass Size	454x131x4mm
Standard Raw Glass Sheet Size	1836x2440mm; 2440x3660mm
Millimetre should leave for glass L. & W. (mm)	0.5mm for each side

 

Raw Glass Sheet Size	1830	2440	1830	2440
Required glass size with add mm when cutting	454+0.5+0.5	131+0.5+0.5	131+0.5+0.5	454+0.5+0.5
Qty after raw sheet divided by requried glass size	4.02	18.48	13.86	5.36
Total qualfied glass qty	4×18=72pcs		13×5=65pcs
Cutting Rate	72x454x131/1830/2440=95%		65x454x131/1830/2440=80%

 

Raw Glass Sheet Size	2240	3360	2240	3360
Required glass size with add mm when cutting	454+0.5+0.5	131+0.5+0.5	131+0.5+0.5	454+0.5+0.5
Qty after raw sheet divided by requried glass size	4.92	25.45	16.97	7.38
Total qualfied glass qty	4×25=100pcs		16×7=112pcs
Cutting Rate	100x454x131/2440/3660=66%		112x454x131/2440/3660=75%

So obviously we got to know, 1830x2440mm raw sheet are first choice when cutting. 

Have you got an idea how to count the cutting rate?