A compressor has a crankcase in which a crankshaft is rotatably mounted in a crankspace. The crankcase contains at least one cylinder space in which a piston, mounted eccentrically on the crankshaft by way of a connecting rod, can be driven in reciprocating motion. The crankshaft is connected, via a gearing having a modulus m, to a drive source, wherein the gear wheel arranged on the crankshaft engages with the gear wheel on the drive source. The axis of rotation of the crankshaft is offset with respect to the center axis of the cylinder space by an amount dl which is a whole multiple of m/2. The center axis of the cylinder space is understood as the axis which proceeds from the center point of the base area of the cylinder space, perpendicular to this base area, and along which the piston moves. This makes it possible to change the transmission ratio of the gearing within an advantageous range, without it being necessary to undertake modifications to the external dimensions of the compressor or to the motive source. Depending on the transmission ratio, it is possible to reduce the operating noise of the compressor or to increase the air capacity.