Calories in dry ingredients vs cooked!

Guys, so when U measure your dry ingredients i.e pasta & it's 100g....does it mean that the entire pot of that pasta when it's cooked will still contain the same amount of calories as specified in the dry ingredients? Or would I need to re-measure 100g of the cooked pasta to get the calories specified on the pack? I'm confused. ????

Also, I made 100g of pasta this afternoon. On the pack it said 100g = 312 calories. The pasta expanded, multipied etc in the pot to something like 300g.I ate it all. Now, will somebody explain to me how many calories of this pasta I ate in total...

Thanks

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