Use your cell phone as a Ruler. You will need to measure the length of the thing. But not around the ruler. Use a ruler of pineapple4 application. More accurate than any a ruler calibrated pixel screen. Two types of devices support, and with one click you can convert. In addition, you can store the measured length.
It's free to download the .apk setup package of Ruler and you can take a look at users' reviews on Droid Informer. This application installation package requires 2 MB of free space to work fine on Android 2.2 and above. The app has been scanned for viruses and it has been found completely secure. Pineapple4 is the developer of this application which can be found in the Tools category.