How much does a a cup of rice weigh?
That depends on the rice. I have done my own measurements in the past (I hate volumetric measurements,) and found:


1 full-to-the-brim rice cooker cup of dry SunRice Brown rice (medium grain?) weighed 142g.
1 full-to-the-brim rice cooker cup of dry SunRice Calrose rice (medium grain) weighed 150g.


Both were Australian grown rice.

The rice cooker cup's top measurement is 160ml, but I always fill to the brim because ... I'm too lazy to look at the notch.

Why is the weight different?

Because different grains of rice can wedge together more efficiently (less air pockets.) The weight measurement for a long grain rice like Basmati would be different again.

TL;DR: buy a scale to be accurate.