



 
Hello Kinsley,
If we assume these conditions hold, then a (very good approximate) formula is given by: Where h is how many inches of fuel on the dipstick, and V is volume in U.S. gallons. This formula is quite SCARY, and probably far more precise than necessary. I recommend keeping a chart with the tank based on some handy divisions of the dipstick, such as this one:
If you require better approximations divide these into smaller intervals, say of a half inch or perhaps quarter inch. With such a large tank, small differences on the dipstick can make quite a difference when it comes to volume. Write back if you need some clarification, or if you are interested in how the formula was obtained. Tyler  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 