How to measure an inch without a ruler
There comes a time in every person's life when they need to measure a small object but they do not have a ruler to do so. By using your thumb, you are able to measure an inch at a time to determine the overall length of an object. Since nearly every person has hands, measuring with a thumb is a relatively simple job.
Place the object that you intend to measure on a flat surface.
Place the tip of your thumb at the edge of the object and measure back to the first knuckle. The 1-inch mark is established by the line on your palm side of the thumb.
Hold the 1-inch mark with the tip of your index finger on the opposite hand and slide the tip of your thumb to the mark to continue measuring inch by inch.