Learning to increase your force in hitting will make a difference. Punching "power" matters more than size ever will. Receiving professional training in how to make use of your fists -- no matter their size -- will ensure that you have the proper form and the correct technique to control the force of your punch.
What Does Matter
No matter the fighting style, people with hands ranging from small to large have become champions. Fist size or hand size in fighting doesn't make any difference at all, but rather the force behind the blow. Small, medium or large hands can deal out a powerful blow if the correct technique is used to put as much force as possible behind the punch. This is often referred to as punching power or power punching according to self-defense trainer, Sammy Franco.
Increasing Your Power
Use a heavy bag or punching bag. A heavy bag, which hangs from the ceiling or from a hook on a stationary pole, can weigh as much as an adult and is an essential part in power punching training. Franco recommends using a heavy bag that weighs 75 pounds or more, since it can withstand the most severe blows. When using a heavy bag for power punching, stay in proper punching stance and keep your body balanced. Keep moving much as you would do when punching a contender, do not remain still. Remain in a relaxed state; do not tense your muscles, which can cause you to deliver slower punches.
No matter what size your hands are, if you are boxing, you wear gloves that create a equal hand ratio between you and your opponent. After practicing power punching with the heavy bag bare fisted, practice using a pair of boxing gloves. Just when your fist is about to hit the bag, or your opponent, tighten it. Tightening your fist on impact improves the speed at which you deliver the punch as well as the power behind it.
Do not stand to far away from the bag or you can overstretch, causing you to risk straining your muscles or spraining tendons in your arm. Overstretching your arm when punching at full speed can also increase the risks of hyperextending your elbow or shoulder joints. When throwing a punch full force, keep your wrist as straight as possible; bending your wrist when punching can cause it to break. If you are unfamiliar with using a heavy bag, see a personal trainer.