Chainsaw Buyers Guide
There are two major types of chainsaws to consider - gasoline-powered and electric. Backyardboss focus's mainly on gas powered saws as they make sense for most applications due to their power and portability (and they are simply cooler). Most chainsaws are powered by two-cycle engines that use both oil and gas mixed together.  

When sizing a chainsaw there are several factors to consider. First, what diameter wood will you be cutting. This will determine what size bar you need. Say for instance that you have a large trunk nearly 40" across. This will necessitate at least a 20" bar to cut though the entire piece. The second factor will be time. If you plan on cutting several cords or firewood, heating a home and maybe having some to sell on the side - then you'll want a large high displacement model that can tear though logs. If your goal is just to clean up a few limbs from the last storm your needs are quite different.
  • Power to Weight Ratio : When shopping for a chainsaw try to find a good combination of size and power. Power matters most if you'll be cutting hardwood (oak, maple, etc.) rather than softwood (pine, fir, etc.). Remember that with power comes weight. A large saw can get pretty heavy after a long session of cutting. Cheap saws tend to weigh more than their more expensive counter parts. Pay attention to the "power to weight ratio".
     
  • Bar length is measured from the cutting tip to where the chain enters the housing. Remember: a saw with a 16" bar can cut through a 32" log. Standard bar lengths typically come in 2" increments starting at 12" and going clear up over 60" on the largest models. While more always seems like better, a longer bar can be very hard to handle and increases the likelihood of running the bar into the dirt which quickly dulls the chain.
     
  • Engine displacement is a measurement of the size of the engines cylinders. Typically a saw with more displacement has more power. Today this logic is skewed some as many saws will share a common engine, but by tweaking compression and fuel ratios the manufactured can change the true power output. The most reputable brands publish both engine displacement and horsepower so you know what your getting.
     
  • Chain pitch is the spacing of each link on the chain. There are several common sizes (3/8  .325, .404) Generally larger links are used on larger saws.
  • Anti-vibration absorbs the shock of cutting the wood and the vibration from the engine. Look for springs and rubber pads on the areas where the handles mount to the chassis. Economy saws have handles attached right to the engine.
     
  • Automatic chain oiler lubricates the chain for smooth travel. Older designs use a manual pump to oil the chain.
     
  • Quick-adjust chain allows the user to change the cutting chain tension without tools. Some systems are better than others, be sure to try before you buy.
     
  • Air Systems many companies offer different sophisticated systems for filtering air and recycling exact to keep filters clean.   

Everyone should have more than just a saw. Protective clothing is a necessary item when running a chainsaw. Dangerous kickback can happen to anyone and the results can be disastrous. 

  • Leg protection such as chaps, leggings or cut resistant pants. Kevlar pants are best and will stop a chain almost instantly.
     
  • Hard hat if there's any material overhead.
     
  • Gloves or mittens with an enhanced gripping surface.
     
  • Eye protection with side shields.
     
  • Hearing protection such as earplugs or earmuffs.
     
  • Boots or shoes with steel toes and nonskid soles.
     
  • Carrying case — provides convenience and helps protect the saw.