What is diecast scale? This is the first question most beginning diecast collectors encounter when they start to buy diecast cars.

The scale of a diecast vehicle is an indication of its size relative to the actual car that it is modelled after. This means that a 1/24 scale diecast toy car is one-24th the size of the actual car.  A 1/18 scale car is one-18th the size of the actual car, and so on.

Note that diecast scale is expressed either as a fraction or as a ratio -- both have the same meaning. So 1/24 and 1:24 are exactly the same as far as vehicle scale is concerned.

For reference, here is a chart of approximate sizes based on scale -- note that the actual size will vary based on the size of the original car that the diecast replica is modelled from:

Diecast Scale	Approximate Size
1/18 Scale	9-12 inches / 24-30 cm
1/24 Scale	6.5-8 inches / 16-20 cm
1/32 Scale	4-6 inches / 10-15 cm
1/43 Scale	3.5-5 inches / 8-12 cm
1/64 Scale	2.5-3 inches / 6-8 cm

 

Thus, a 1/18 scale diecast car is usually about 24 - 30cm (depending on the size of the actual car).  A 1/24 scale diecast car is generally about 16 - 20cm. Many of the cars made in the smaller scales (1/32-1/38) are actually made so that the car will be exactly 5 inches long, regardless of the scale. The 1/64 scale cars are a similar size to "matchbox" cars, usually 6 - 8cm.

The picture below references how the different scales compare to each other:

Finally, it's important to note that larger vehicles, such as trucks or construction vehicles, are often made on a smaller scale (1/50 or 1/64), but are in fact about the size of 1/24 scale cars, since the actual vehicle is much larger.

Here is a complete list of scale sizes with more info from Wikipedia