How to Make Onion Powder From Scratch

High angle view of minced onion with garlic salt and powder

Michelle Arnold / Getty Images 

There's no need to buy those tiny jars of onion powder. Why spend the money if you can learn how to easily make it yourself? Besides being a cost-saver, it also tastes better. Once you know how to make it yourself, you'll be able to keep this staple on-hand in your spice rack.


There is no great secret to onion powder. All you need is a few fresh onions. And, it's the perfect solution for using up those onions you bought last week that are just starting to get past their prime. In just an hour or so, you'll be able to produce enough onion powder to last you quite a long time. And, in addition to using it in soups and casseroles—it can also be used to make onion salt

One or two onions are often enough for the average family of four to use for a very long time. And, if you want, you can always add more onions and to make a larger batch. Should you find that you got over-zealous and made too much, you can put some in small mason jars and give them to family and friends—everyone likes a homemade gift.


Begin by peeling your onions and using a sharp chef's knife to chop them finely. Spread the onion pieces out on a tray and heat them in a 150-degree oven or place in a food dehydrator until dry. You'll know the onions are done when you can easily crumble the chopped pieces in your hand.

Allow the dried onions to cool before grinding into powder. You can easily grind them up with a coffee grinder, spice mill, food processor, or mortar and pestle. Keep grinding until the mixture reaches your desired consistency. 

Storage and Shelf Life

Store your finished onion powder in an air-tight container in a cool, dry spot. You can also freeze any excess. As with any dried spice or herb, it's best to shake the container at least once a day for the first week so it doesn't glob together. And, shaking distributes any leftover moisture evenly and prevents mold from growing.

Be sure to label the jar so you don't mistake it for other spices like garlic powder. An inexpensive option is a piece of masking or painter's tape used on a recycled spice jar. These tapes won't leave a sticky residue and are easy to remove but adhere well until you wash the jar again.

Onion powder has a surprisingly long shelf life. A commercially dried powder can last as long as three or four years. However, your homemade version may not meet such exacting standards. Depending on how well it's dried, expect your onion powder to stay flavorful for up to a year in a well-sealed container. Since this is so easy and cheap to make, you might even consider making a batch as often as twice a year.

A Word About Coffee Grinders

Although you have a few options, coffee grinders do a quick job when it's time for grinding any spice. You'll get the finest onion powder from a coffee grinder and you can always grind less if you prefer it a little more coarse.

It is best to designate separate grinders for your spices and your coffee. Things like onions and garlic are very pungent and the smell can be very difficult to remove from the grinder.

The good news is that coffee grinders tend to be pretty inexpensive. You can pick up a simple one just for your spices and set aside your good grinder with all the bells and whistles and use that for coffee.