Based from the data from the Municipal Accessors Office, Quezon occupies an area of 268.26 km² or about 2.52% of the total land area of Isabela which is placed at 10,664.4 km². The figure was based on the actual tax mapping conducted by the said office. The same figure was also used in the old town plan of Quezon and was validated by using a digital planimeter. With this figure, Quezon is the 13th largest of the 34 municipalities of Isabela and the 3rd largest out of the 11 municipalities of District 2 (San Mariano being the largest at 1,469.50 km², followed by Aurora at 300.56 km²). It is larger than its neighbors Mallig (133.4 km²) and Roxas (184.8 km²).