I was thinking mine was 15, but it may be 17. I dunno, but when my truck is below empty, and the "check gauge" light comes on warning of low fuel, I fill it up, and only can get like 12 gallons in, maybe 13 once or twice when i really pushed it. I know its at least 15, but dang, that fuel gauge is way, way jumping the gun, especially if its a 17 gallon tank. My g/f always thinks we are gonna run out of gas, but i always keep track of the miles, just in case the gauge decides to let me down. lol