In choosing a bat for your child, the basic parameters that you have to worry about are:

• The bat’s length (in inches)
• Its weight (in ounces)
• Its barrel diameter (the fat part of the bat, in inches). 

Length and weight are related by a bat’s minus number – the difference between the bat’s length (in inches) and its weight (in ounces).  A 30-inch “-7” bat will weigh 30 – 7 = 23 ounces, while a 30 inch “-10” bat will weigh 30 – 10 = 20 ounces.

The big issue with bats is the weight.  Most coaching books caution against letting a child use a bat that’s too heavy.  I can’t argue with that; if the hitter can’t get the bat around he won’t be able to hit.  But with today’s aluminum bats, it’s more common for kids to use bats that are too light.  As a result, they don’t have to use proper mechanics to swing; they can simply muscle the bat around with their arms.

So what is a good weight for a bat?  To help us, the bat industry has divided bats into three basic age categories: Youth, Senior, and High School/Adult.  

YOUTH. Youth bats are for ages 7 to 12.  They generally come in the -8 to -12 range.  The standard barrel diameter is 2¼ inches.  Occasionally, you may see one with a 2 5/8 or even a 2¾ inch barrel.  A fatter barrel is better, but check with your league first to see if the larger diameters are allowed. 

Here are my general guidelines for this age group.  Adjust up or down a bit depending on your child’s size, weight, strength, and athletic ability.

§         AGE 8: 26 inches, 16 ounces (-10)

§         AGE 10: 28 inches, 18 ounces (-10)

§         AGE 12: 30 inches, 20 to 22 ounces (-10 to -8)

SENIOR.  No, the senior age group does not refer to folks over the age of 55; it’s for kids from 12-14, mostly 7th and 8th graders.  Senior bats come in the -5 to -8 range, and with 2¼, 2 5/8, and 2¾ inch barrel diameters.  I recommend buying the largest barrel diameter that your league permits; but check your local league rules before buying a 2¾ inch diameter barrel bat!  Most leagues allow the 2 5/8 inch barrels for the senior age group, but many do not allow the 2¾ inch barrels.

It’s hard to develop a specific age guide for this group because the kids can vary so much in size and weight.  I’ve coached kids in this age group who weighed in at 80 pounds and others who weighed in 180 pounds.

§         Smaller kids (~80 lbs): 30 or 31 inch bat in the 21 or 22 ounce range.

§         Average kids (~100 lbs): 31 inch, 23 to 24 ounce bat

§         Bigger kids (>140 lbs): 32 inch bat in the 24 to 25 ounce range

But consider your player’s strength and athletic ability when choosing.  The player should be able to hold the bat straight out at arm’s length for 30 seconds without straining.  If he can’t, the bat’s too heavy.  If he isn’t straining a bit after a minute, the bat may be too light.

High School/Adult.  High School and college players are required to use -3 bats, even in most recreational leagues.  Barrel diameters must be 2 5/8 inches.  That makes it rather easy.  The -3 bat is not as light or resilient as youth or senior bats; the ball doesn’t jump off these bats like it does the -7 bats.  The -3 bat approximates the performance of a wood bat, and was adopted as a safety measure to protect pitchers.  Since the -3 bats are heavier and don't have as much "pop", it's important to use proper mechanics to generate bat speed and power.

Many kids find the transition from a -7 senior bat to a -3 adult bat to be difficult.  I recommend starting with a 32 inch, 29 ounce bat (-3).  Some adult bat models have a 31 inch (28 ounce) size, but most start at 32 inches.

Some adult recreational leagues allow -5 bats.

Bat Models.  Bats seem to come in innumerable models and prices.  If you read the manufacturer’s advertising, all of them sound wonderful.  So how do you pick?  Truth is, I don’t have many clues myself.  Generally I choose an established maker, a size and weight range, and a price range, which narrows my choices down to several hundred (well, maybe a dozen or two) bats.  Then I read the advertising and make a random selection.  But as Ted William’s used to say, “It ain’t the arrow, it’s the Indian.”

My son used to complain about getting “stingers”, vibrations that sting the hands when you hit the ball off center.  There are now two-piece (aka “connection”) bats that are joined together somewhere near the middle of the bat.  The bat makers claim this allows them to make the handle stiffer and barrel more flexible, allowing greater “trampoline effect” when you hit the ball.  While this may be true, it has the added benefit of isolating the vibration of the barrel from the handle – the result is fewer “stingers”.  So if stingers are a problem for your player, consider a two-piece bat if it fits your pocket book.