Abstract: An extendable carpenter's level which comprises a pair of extending body members capable of adapting and mounting upon the standard “I” level frame configuration of a carpenter's level by sliding said extendable body members onto the frame of the standard level. Each extending body member consists of a top and bottom slide extension rigidly attached to one another so as to be firmly in contact with the level frame. The top and bottom slide he extensions each incorporate a lock pin to insure rigidity as against the level frame and stop clips to eliminate outward extension of the extending body members beyond the end of the level frame. In another embodiment, each extending body member is split such that both the top and bottom slide extensions comprise generally a right and left side extension held together by means of slide springs and flush mounted screws.