Both the german and English use of 'meter' is confusing in this question and answer. In English 'Metre' is a distance and meter is an instrument. In german it appears 'gasmeter' is Durchflussmesser (so messer is perhaps =the English use of 'meter'). It seems the distance in the US is spelt normally 'meter'. Online dictionaries suggest 'metre' is the correct spelling for the distance in German.
"der Meter" is the distance in German. "metre" is not in use for any meaning. Instruments for measurement are commonly called "XYmesser" (XY standing for whatever is being measured, note the German prevalence for combined nouns), but it may also end in -meter, especially if the first part has Greek roots as well, like "das Barometer", "das Thermometer", "der Tachometer". But you would not call an instrument just "Meter" in German.