How many gallons of fuel does a f15 fighter jet carry?

Internal the F-15 holds about 13,455 lbs of fuel which is (depending what weight number you use) about 1979 US gallons of fuel. External fuel on three hard points can handle up to 3 x 600 US gallons of fuel plus F-15C and E's carry that with what are called conformal tanks. They hold 750 US gallons of fuel.

So, say a F-15C on a long transfer trip to the Middle East will carry, 1979 gallons with three hard points drop tanks with a total fuel of 3779 gallons of fuel