Conversion Tables

Most common examples (I'll update it in case we'll find something new or particular).

Flour: 
Cups > Grams > Ounces
1 Cup     -  128 gr. -  4.5oz
3/4 Cup  -  96 gr.   -  3.38oz
2/3 Cup  -  85 gr.   -  3oz
1/2 Cup  -  64 gr.   -  2.25oz
1/3 Cup  -  43 gr.   -  1.5oz
1/4 Cup  -  32 gr.   -  1.13oz
1/8 Cup  -  16 gr.   -  0.563oz

Sugar: 

Cups > Grams > Ounces

1 Cup     -  201 gr. -  7.1oz

3/4 Cup  -  150 gr. -  5.3oz

2/3 Cup  -  134 gr. -  4.73oz

1/2 Cup  -  100 gr. -  3.55oz

1/3 Cup  -  67 gr.   -  2.37oz

1/4 Cup  -  50 gr.   -  1.78oz

1/8 Cup (2 Tablespoon)  -  25 gr.   -  0.90oz

Butter: 

1 Cup of Butter = 226 gr.

1/3 Cup of Butter = 76 gr.

1/4 Cup of Butter = 57 gr.