How this calculator works
Herbs lose water when dried, so the same leaves occupy much less space and the flavour is more concentrated. Extension services give a working volume ratio: one tablespoon of chopped fresh herb replaces about one teaspoon of dried herb, a three-to-one ratio. Ground or powdered herbs are finer still, and one teaspoon of dried leaf is usually replaced by about one quarter teaspoon of the ground form, a four-to-one ratio. These are cooking guides, not laboratory measurements. Dried herbs also lose potency over time, so an old jar may need more than the ratio suggests.
Formula
fresh volume = 3 x dried volume. dried volume = fresh volume / 3. ground volume = dried volume / 4. Combining them, fresh volume = 12 x ground volume. One tablespoon fresh equals one teaspoon dried and one quarter teaspoon ground.
Worked example
A recipe needs 2 tablespoons of chopped fresh basil. Two tablespoons is 6 teaspoons, so use 6 / 3 = 2 teaspoons of dried basil. For ground basil, 2 teaspoons of dried leaf becomes 2 / 4 = 1/2 teaspoon. Going the other way, 1 teaspoon of dried thyme stands in for 3 teaspoons, or 1 tablespoon, of fresh thyme leaves.
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Frequently asked questions
Does the three-to-one rule work for every herb?
It is a good general guide, but strong herbs such as sage, thyme, oregano and rosemary can be more concentrated when dried, and some cooks use only a two-to-one ratio for them. Delicate herbs such as parsley, cilantro and chives are often used fresh because dried versions have little flavour, so the ratio matters less.
When should I add fresh or dried herbs?
Dried herbs benefit from more contact with heat and liquid, so add them early in soups, stews and sauces. Fresh herbs are usually added near the end, or at the table, to keep their aroma. Some fresh herbs, such as basil, turn dark and bitter with long cooking.
Why does the calculator use volume rather than weight?
Most home recipes measure herbs by spoon. Weight-based conversion would need the packing density of each dried herb, which changes with how leafy or powdery the jar is. The volume ratio is more practical, though it is less precise.
Can I use this for leafy spices such as bay leaf?
Bay leaf is usually counted in whole leaves rather than spoonfuls. One dried bay leaf replaces about one fresh leaf; the leaf is removed before serving. The volume ratio is not useful for whole leaves, so use it for chopped or crushed herbs.