Can I use prepared mustard instead of dry mustard?
In most cases you can use 1 tablespoon of prepared mustard in place of 1 teaspoon dried mustard. However, if the amount of prepared mustard called for in the recipe is 1/4 cup or more, it's contributing to the volume, so you may need to increase one of the other ingredients of a similar consistency to make up the difference.
For more ingredient substitutions, see our alphabetized Ingredient Substitutions chart.
Or, if you are interested in making your own mustard, see this recipe for Ballpark Beer Mustard.