Choosing the correct laptop adapter is all a matter of voltage, output power, and proper connection. If all of these things do not match the original specifications of your computer, than a new laptop adapter will likely not work on your machine and may potentially cause a lot of damage. In the end, most replacement adapters will have a list of computers they are compatible with.
The first thing to consider for the laptop adapter is the voltage. The easiest way to check this is to turn the computer over and see if there is a voltage listed anywhere on the bottom of the machine. A sticker may be affixed with this information and other similar laptop specs listed. It should be a number with a V attached to it, such as 19.5V. This information is also available on the original adapter, if it is available.
The second thing to look for is the current output needed for the laptop adapter. This number will have an A of mA associated with it. For example, it may say something like 4.7A or 950mA. These numbers ensure that the power going to your machine will be acceptable and keep it operating within normal parameters. Not paying attention to either of these numbers could cause the electrical systems in the computer to malfunction and quit working altogether.
Once these two issues have been settled, the other important step is simply to make sure the connection fits the port in your computer where it is to be plugged in. The voltage and output current of the laptop adapter will not matter if it is not able to be connected. If ordering online or if you do not have your computer, it is advisable to check this out as soon as possible.
Many may choose the safest route possible and go with a replacement laptop adapter directly from the manufacturer, if available. While this is a good option, these parts may be more expensive than others that may be available from after-market manufacturers. Further, as long as the numbers match, all should work nearly the same and be just as safe and effective.
Another thing to consider is whether you want an AC laptop adapter or DC adapter. An AC adapter is made to be plugged into any standard electrical outlet such as those in a home or office. The DC adapter is made for automobile use.
Typically, laptop adapters can be found for sale anywhere computer accessories or laptop batteries are sold. Though the price will depend on the model and manufacturer, most tend to run between $40 US Dollars (USD) and $100 USD. They are also available from many online retailers as well.