Buying scale models is a common hobby for children and adults alike. Figuring out the scale of the model is a simple mathematical process. You will need to know the size of the model you have, and the size of the original. If you know the size of the model, and the scale, then you can determine the size of the original object. With a relatively simple calculation, therefore, you can figure the size and scale of models.

Measure the dimensions of the model that you have. Measure height, width and any other dimensions that seem relevant. Although you only need one of these to work out the scale, for mathematical simplicity, a range will allow a simple calculation to be found. It doesn't matter whether you use imperial or metric units, although it is best to use the units that the original object would have been measured in.

Find the measurements of the original object. This can be determined using the Internet, an encyclopedia, or a trip to a museum. Again, be sure to take as many dimensions as possible, since this will help with the math at a later stage.

Convert the units so that they are the same. This will involve working out the larger object's dimensions in the units you have used to measure the model. If the wingspan of a model 747 plane is 6 inches, and you know that the wingspan of a real 747 is around 200 feet, then you must convert 200 feet into inches. Since 12 inches is one foot, 2400 inches is 200 feet.

Divide the dimension of the real object by that of the model. In the example selected, 2400 inches divided by 6 is 400. The model is therefore 400 times smaller than the original object. This can be clarified by conducting the same calculation with other dimensions. The means by which this is shown is "1:400," or for every 1 inch on the model, there are 400 on the original object.

Calculate the size of the object using the model size and the scale by juggling the formula. For example, if you know that the length of your model 747 is 7 inches, and the scale is 1:400, then you can work out that the length of a real 747 is 400 by 7 (2800 inches), or 233 feet and 4 inches.