From Star Trek II The Wrath Of Khan [Kit]

Diecast models are manufactured to various scales based on measurements taken from the actual vehicles. The rule to remember is the higher the scale number, the smaller the model!

So, 1:2 scale quite ltierally means it is 1/2 (half) the size and 1:4 scale means it is 1/4 (quarter) the size.  Here is a rough guide to the size of our models although this will vary depending on the size of the actual vehicle. Please note that the scale and size of models differs per department. Please refer to the individual product page to find out the estimated size of the actual model you would like to purchase.

Bikes

1:32 scale will be approximately 5cm long
1:24 scale will be approximately 8cm long
1:18 scale will be approximately 10-12cm long
1:12 scale will be approximately 14-18cm long
1:10 scale will be approximately 20-28cm long
1:6 scale will be approximately 30-38cm long

Cars

1:64 scale will be approximately 6cm long
1:43 scale will be approximately 10cm long
1:24 scale will be approximately 15-25cm long
1:18 scale will be approximately 20-30cm long
1:12 scale will be approximately 30-40cm long