What's a good website to check for the right replacement battery for a watch?

Question

I need watch batteries for three different watches. Why is it so hard to find information on the internet as to what battery I need to pick up? I can replace it myself if I knew what size to buy.

One's a Citizen, one's a small Swatch, and one's a Carriage by Timex.

tvguy, thanks for the answer. But I don't feel comfortable opening it up twice, once to looksee what battery's inside and a second time to place it. And I cannot have the parts loose as I have small kids and they could lose them. I want to buy it first with whatever site or resource is available and then open one time only.

Answer 1

Open the watch.
take out the battery. Each battery has the brand name and part number.
You can buy the same brand/part #, or it is easy to find equivalent batteries by other brands at any store that sells watch batteries.