system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Do gas pumps really measure dispensed gas to the thousandths? And if so, how?
gpt
Gas, fuel, diesel etc is typically measured using a special flowmeter called a turbine meter. Basically, the fuel is pumped through the turbine meter on the way to the nozzle. The turbine meter contains funnily enough a turbine which spins as the fluid passes through it. The spinning spindle of the meter has magnets on the shaft which trigger pickups on the outside of the meter which allows the number of rotations of the turbine to be counted. The turbine meter is carefully calibrated so the amount of fuel per revolution is known and thus the amount of fuel passing through the meter can be calculated.

The meters can be extremely small so the volume of fuel per revolution is extremely low allowing for very high accuracy.