* Your owner's manual: This is the most reliable source.
* The fuel filler door: The capacity is sometimes printed on a sticker inside the fuel filler door.
* Your vehicle's specifications: You can often find this information online by searching for your Blazer's year, make, model, and trim level.
Expect the capacity to generally be between 15 and 20 gallons, but again, this is just a range; the exact amount will vary.