Do you weigh the same after farting (flatulence)?

No, you will lose a few milligrams of gas and pong. read more

The next time you feel a fart coming weigh yourself on a very good scale before and after you release gas into the air, then you will know its exact weight by what you have lost into the atmosphere. Alternatively you can estimate the amount of gas released. Here is a guideline: A study showed farts averaged between 17 to 375 cc of air. read more

The case of whether flatulence is lighter than air itself depends upon the specific case as well a bit, but is going to be a true in the majority of all cases. The hydrogen and methane contained in much flatulence are both lighter than air. read more