The present invention is about a device used to quantify biomass shredded by shredders, flail mowers or choppers by measuring mechanical stresses. This system allows real-time measurement of biomass during shredding, eliminating the need for additional mechanical operations. The device is installed on the structure of the machinery and is able to measure the acceleration and angular velocity of the machinery in order to record the vibrations of the shredder. The vibrations are affected by the amount of biomass shredded. By recognizing the different vibrations, the device is able to understand the percentage of biomass present quickly and easily. The device can be placed near the shredder and easily installed on the protective cover of a shredder, on the ejection pipe of a chipper, or on a forage harvester.