Abstract: A firmness measuring method and device for non-destructive testing of objects (such as fruits) is disclosed. The device comprises the following components: a means to affect the size and/or shape of the object(s) through application of a compressive force (such as increased liquid, fluid, or mechanical pressure); or an expansive force (such as decreased liquid, fluid, or mechanical pressure); a means to measure or infer the volumetric change of the object(s) caused by application of the force; and/or measurement of surface deformation; an analyzer to utilize the volume change and/or amount of deformation of the surface caused by the applied force to infer the firmness of the object(s); a controller to coordinate the application of force, the measurement of object(s) response and the inference of firmness or firmness. Inference of firmness may also use additional information on the object(s) such as harvest date, manufacture date, weight, variety, chemical concentration, or water content.