How much gas is left when gas light comes on?

Not enough!!... If the tank get that low, possible fuel pump damage can occur... Gas is what cools the in tank electric fuel pump, it is best to keep at least 1/4 tank of fuel..

Varies a LOT!! With my '95 Camry , i have about 3 gallons in 'reserve' , but in a new(2015) Odyssey less than 1&1/2 gallons! BEST to keep track of fuel economy for a few tankfuls , then say, if you normally get 300 miles before the low fuel light comes on , either keep a gas can with you and experiment(run out) or just get gas as needed. ...... But yep , it doesn't hurt to know , in case ....

My 96 Quest has 3-4 gallons of fuel left when the fuel light turns on. When the light turns on see how many gallons it takes to fill the tank.