An adjustable measuring device for measuring contents, such as liquids and granulated solids, having a usable volume for measuring. The adjustable measuring device includes a housing, a platform having a lower position and an upper position, and an adjusting system for moving the platform between the lower position and the upper position. When the platform is in the lower position, the usable volume is maximized. When the platform is in the upper position, the usable volume is minimized. The adjusting system comprises a restraint system adapted to maintain the platform between the lower position and the upper position. Also, the adjusting system comprises a discrete locking system adapted to temporarily lock the platform into a plurality of predetermined positions, which represent discrete usable volumes. By applying a first adjusting force, the platform moves toward the upper position. By applying a second adjusting force, the platform moves toward the lower position.