A low-cost, compact electro-optical leveler, using a CMOS image sensor, has been developed for level measurement. The two-lens optical system is designed to find the tilt information for the total system. ZEMAX is used to design and predict the performance of this optical system. One lens is bowl-shaped so that it can hold a liquid. The centroid of the light spot on the CMOS image sensor is converted into pixel coordinates proportional to the tilt angle to be measured. The experimental results verified the simulation results. The reading tilt angle can be estimated with a resolution at better than 8 arcsec.