Toys come in a variety of sizes from small, i.e.,, micro to very large, i.e., ‘model’ trains that are for the outdoors. Therefore, when looking to buy a toy consider the age of the child you are buying for and the intended purpose. Is the gift going to be meant as a plaything or to be set on a shelf as a collectible?
If the child is very young, look for toys that they cannot put into their mouths and does not have small parts that might be broken off. If the child is older, some of the highly collectible items, such as Hot Wheels, NASCAR and train sets can offer both play time, collectability and come in a variety of scales. When talking about scale, we are talking about the measure of the size of the toy item vs. the size of the original it is based on. You may remember from math class this can also be the ratio.
Various train sizes range from those large enough to be ridden to those that you often see set up as models. Often times, in addition to an elaborate track layout, you’ll find landscaping, cars, people and animals included. Train scale is measured not so much by the size of the train itself (engine, cars, etc.) but rather by the size of the track or gauge. Some of the most popular gauge or scale measurements are: 
- G – often referred to as ‘Garden Scale’ as it is large. Scale can range from 1:22.5 to 1:29. A typical 40′ box car would be 17.25″ L x 4.50″ W x 6.50″ H.
- O – most common and what we typicall think of; like Lionel. Scale is 1:48. A typical 40′ box car would be 10.50″ L x 2.50″ W x 3.75″ H.
- HO – most popular. Scale is 1:87.1. A typical 40′ box car would be 5.75″ L x 1.50″ W x 2.00″ H.
Other scales used for model trains are S (1:64), TT (1:120), N (1:160), Z (1:220), OO (1:76.2), 1 Scale (1:32), and T (1:450).
The size for these cars is based on the size of the actual car, truck or other vehicle. The most popular size used by Hot Wheels and Johnny Lightening is the 1:64 scale. A good rule-of-thumb for determining the difference in the sizes is: 
- 1:12 scale = 14″ – 16 ” in length – Highly detailed, often featuring motorcycles.
- 1:18 scale = 8″ – 11″ in length – Detailed model targeting the adult collector market.
- 1:24 scale = 5″ – 8″ in length – Favored scale for model kits; also used by Franklin Mint.
- 1:43 scale = 3″ – 5″ in length – Most popular around the world and used by Dinky.
Other popular scale sizes are:
- 1:32 – used by Ertl and Britians
- 1:64 – used by Matchbox, Hot Wheels, Johnny Lightening.
- 1:87 – used by Herps, popular due to their compatibility with HO trains.
Seemingly a cross between die-cast and trains by making use of a track are slot cars. These scaled down cars make use of actual car bodies that have been tailored for racing. Raced on a ‘slotted track’ these cars are controlled by a hand-held controller. Might add that new digital technology now has it where these cars can not only change lanes but share lanes. Similar to other scales, you’ll find slot cars in the following:
- 1: 24 – larger size so they are typically run on commercial or club tracks.
- 1:32 – most common home ‘friendly’ size; also popular at clubs and hobby shops.
- HO (1:87 – 1:64) – originally designed for train layouts; size may vary due to need for larger motor.
These cars have also been produced in 1:48 (1960’s) as well as 1:43 scale (2007 – today) although it would appear there is little ‘organized’ racing.
Scale can be used to fine a toy, based on individual desire or purpose. However, shopping for a gift should simply be based on the person it is intended for and if it is to be played with or collected.