In article , Ron Lee wrote:

...I have to agree with Marc on this. I know very accurately how much
fuel I have since I have run the tanks dry to "calibrate" my fuel
gauge (and engine monitor fuel gauge)...

That's one way to calibrate the gauge. Perhaps since my Pitts has one tank I
simply drained and refilled it on the ground. The fuel flow gauge is
now accurate to a tenth of a gallon every time I refill.