Privacy Friendly Tape Measure can measure the size of objects in pictures based on objects of known sizes (e.g. coins) in the same picture. Just find a coin or other reference object of a known size, put it next to the item you want measured and take a picture. Make sure all objects are in the same level and the picture is taken perpendicularly to it. Now you can mark the reference object in the picture and measure any length or area you want!

Privacy Friendly Tape Measure belongs to the Privacy Friendly Apps group developed by the research group SECUSO at Technische Universität Darmstadt. More information can be found an https://secuso.org/pfa