First and foremost, you need to be aware that you should always choose and eventually use extension cords based on what you are doing compared to the rating and capacity of the electrical extension cord.
The best analogy is putting out a fire with a garden hose. Would you use a garden hose to put out a fire started in small trash can? Maybe...Even, Yes. Would you use that same garden hose to put out a major forest fire? No.
Extension cords are just like garden hoses.
1. The electrical current, (measured in Amps), flowing through the cord is just like the water flowing through a garden hose, (gpm).
2. The electrical volts measured by what the cord is connected to is like the pressure, (or psi), of whatever the garden hose is connected to.
So, it would stand to reason that just like you would never consider hooking up your garden hose to a fire hydrant, you would never want to plug in an electrical extension cord that is undersized for the tool or device that you plan to run on that cord.
Here are the basic sizes of the cords and what they are used for: (Gauge is a size measurement of the wire...The smaller the number, the LARGER the size of the copper wire....I know, it doesn't make sense does it?)
#18 gauge, or, (sometimes #16 gauge): Lamp Cords
#16 gauge: Electric Trimmers and Work Lights
#14 and #12 gauge: Power Tools such as Circular Saws
#10 gauge: Heavy Loads like industrial generators.
(See Picture above this blog)
#12 through #16 gauge extension cords are commonly sold in hardware and retail stores. I would recommend purchasing an electrical extension cord from a source that can answer your questions about whether it will fit your particular application.
Lastly, ALWAYS buy extension cords that have a ground prong on them. And, if you are using one of those roll up storage devices to store your extension cord, DO NOT use the device without first uncoiling the roll of extension cord before use. Why? Heat can build up if the extension cord is rolled up while it is being used. The insulation around the electrical cord can melt and start a fire.
Always use the proper tool for the job. In this case, the tool includes any electrical extension cord you plug into that "proper tool."
Be Safe and Warm Regards,