Proportioning provides accuracy to the sketch by comparing and measuring the features of the subject. Though the processes for proportioning a live model or a photo image are similar, the tools are different. The tools used to proportion a live subject include a pencil or sewing gauge, while the tools used to proportion a photo image may also include a divider.
When proportioning a live model, lock your arm forward with a pencil held straight up and down. View the top of the pencil to the top of the subject and slide your thumb down the pencil. Hold your thumb in place when you’ve chosen a unit of measurement. Now you can use that measurement to determine the length and width of some of the features. You can use a sewing gauge instead of a pencil for similar results.
Find a feature of the subject that can be used as a unit of measurement. In this example, we use the distance from the top of the head to the top of the leg as a unit to compare measurements of other features.
Take time to look for similar widths and lengths in your subject when you are beginning a sketch. In this example, if we compare the unit of measurement of the height of the knee to the top of the head, we find it is the same distance as the knee to the elbow. You may find something else in the figure to measure to use as a proportioning unit.