How much does a a cup of rice weigh? I use the cup that came with my rice cooker to measure the rice for each meal. 

I often eat 120ml~160ml rice (before cooking) measured in the cup at a time. How much does that amount of rice weigh? (I don't have a scale). The purpose of the question is to plan how much rice to buy at a time..
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.