Fresh herbs and dried herbs are not interchangeable spoon for spoon, and that is where most recipes go wrong. Drying removes water and concentrates flavour, so a spoonful of dried herbs is much stronger than a spoonful of fresh ones. The classic rule is three parts fresh to one part dried: one tablespoon of fresh herbs equals about one teaspoon of dried herbs, and this free converter applies that rule while adjusting it for each herb type.
Why three to one? Fresh leaves are mostly water, so when that water leaves, the flavour compounds pack into a smaller volume. A tablespoon of fresh basil, loosely packed, shrinks to roughly a teaspoon once dried and crumbled. That ratio holds well for soft, leafy herbs like basil, parsley, cilantro, mint, and dill, which lose a lot of bulk when they dry.
Woody herbs behave differently. Rosemary, thyme, oregano, sage, and bay are already dense and strongly flavoured when fresh, so they lose less punch in drying. For these, this converter uses a two to one ratio instead of three to one, which keeps the dish from turning bitter or medicinal. Bay leaves are a special case: count whole leaves rather than spoonfuls, and always remove them before serving.
To use the tool, enter your amount, pick tablespoons or teaspoons, choose the herb, and pick the direction of the swap. The result shows the converted amount in teaspoons, with a tablespoon conversion when the amount is large. If your recipe lists fresh herbs but your cupboard only has dried ones, run the conversion the other way round and you will land close to the intended flavour.
Timing matters as much as amount. Dried herbs need time and heat to release their flavour, so add them early in cooking: at the start of a soup, stew, or sauce. Fresh herbs are the opposite: heat destroys their bright, delicate notes, so stir them in at the very end or scatter them over the finished dish. Swapping the timing as well as the amount is a common reason a converted recipe still tastes off.
Measuring technique changes the result too. A tablespoon of fresh herbs should be leaves lightly packed, not crushed into a paste and not loosely heaped. Dried herbs should be crumbled between your fingers as you add them, which wakes up their oils. If a recipe says one tablespoon of fresh chopped basil, measure the leaves first, chop them, and then convert, rather than converting a chopped measurement.
Some herbs simply do not dry well, and no conversion fixes that. Basil loses much of its fresh perfume when dried, so dried basil works in long-cooked sauces but never matches fresh basil in a salad or a pesto. Cilantro and parsley also fade badly. In those cases, if you cannot find fresh herbs, it is often better to leave the herb out or use a different fresh herb than to force a dried swap.
A frequent mistake is doubling the dried amount because the dish tastes weak at first. Dried herbs bloom slowly, so a stew tasted after ten minutes will seem under-seasoned even when the final amount is right. Wait until the dish has simmered properly, then taste and adjust. Adding more dried herbs late in cooking gives a dusty, raw flavour that no extra time fully fixes.
Store dried herbs away from heat and light, in sealed jars, and replace them after about a year, since old dried herbs lose strength and taste like dust. If your jar is older than that, use a little more than the converter suggests and taste carefully. With the right ratio, the right timing, and fresh jars, the swap between fresh and dried herbs becomes routine rather than a gamble.