If you use a small scale, it is a good idea to occasionally verify the scale. You do not want to cheat yourself, have an angry customer, or have to resend a package because the weight was off. Here are a few simple options you can try out.
If you live in the U.S.A. you can use quarters. Each quarter weighs for all practical purposes .2 ounces. That means there are five quarters to 1 ounce. Every five quarters you add is another ounce. Keep your quarters into a snack size bag and you won’t have to count them out, or be inconvenienced by going to the bank to get quarters.
A package of meat from the store will also get you close. All cuts of meat and hamburger meat sold over the counter is weighed for proper pricing. The package of whatever meat you buy will weigh the printed weight. When you are going too use the meat, weigh the meat by itself on a piece of plastic wrap on your scale. If there is no liquid left in the packaging, your scale will be calibrated to the meat market scale. This method also keeps the butcher shop honest.
If you buy prepackaged meat or any other product, there is always a range of weight. A pound of lunch-meat is rarely 10 ounces. Usually it will be somewhere between 15.5 and 16.5 ounces. Same with canned goods, or bottled liquids. The wight they show is part of a range of acceptable weight, usually, but not always no the lighter side of the weight. Because the products are packaged at high speed, the manufacturer wants and overall correct weight, not a precise weight on each item.
If you really want to get exotic, a dry measure cup of table salt weighs about 10.6 ounces. If you use granulated sugar, a dry measure cup weighs about 4 ounces.
If you have a very light weight plastic bottle with a seal-able lid, you can use water to verify your scale. One-quarter cup of water measured correctly is 2 ounces. One cup of water is 8 ounces. Two cups of water is 16 ounces, or one pound.
One last and easiest method, where you do not have to bother with measuring and finding the weight, is after your scale is verified, pick a couple of nick-knacks, piece of unused silverware, glass, coffee mug, or any rarely used household item and weigh it. Write down the item and the weigh. Use a variety of weights depending on your scale. This way when you next go to verify your scales calibration, you will have the items handy, and the weights verified.
Of course if you need ultra precise weights for your scale calibration, you will need to purchase calibrated weights. If you are selling through a web page on the internet, adding an ounce to the shipping weight will be sufficient for almost any calibration verified scale.
Using a little creativity, you will never be surprised to find your online customer had to pay out of pocket for additional shipping because your scale was off, or have a package returned because the postage was not adequate.