Abstract: The basic concept of the fuel gauge of this invention is to make use of the difference in refraction of liquid and air by means of optical fibres. More particularly, the fuel gauge includes a first set of optical fibers connected to a light source, a second set of optical fibres connected to a display unit and an optical medium mounted between the first and second sets of the optical fibres in such a manner that the light transmitted through the first set of the optical fibres is allowed to enter the second set of the optical fibres only through those optical fibres which are submerged in fuel. The light transmitted to the second set of the optical fibres may be converted into a visual signal with an existing display mechanism.