There are different conversion factors depending upon whether you are looking at length or mass etc and also on the "customary" (eg inch, foot, mile) and metric units (eg centimetre, metre, kilometre). There are a number of common conversion factors in Wikipedia at the link given with his answer.
To convert the American recipe, you need to introduce the foreign recipes.
Yes, there is a site called science made simple online that allows you to convert from the metric system for your recipe. It has a detailed chart that you can easily follow.
You may need to convert it if you are scaling up or (down) the recipe to feed more (or less) people. You may also need to convert between metric and imperial measures.
Measurement converters are a great tool to have when baking a recipe. Often a recipe will call for grams or ounces and one must convert this to cups. Many cook books have a section within which includes a converter. Convert Me is a great online tool which one can use to convert different measurements.
The measurement for cooking oil from a British cookbook could be given in two different terms: because the old English Imperial, different at times than the US Imperial, is the older type of cookbook, and at some time in recent years, the British weights and measurements CHANGED TO METRIC. So, it depends on how old your cookbook is. If it's an old version, then the cooking oil would be measured in fluid ounces; if its' a modern metric cookbook, it will be measured in terms of mL or millilitres. This is true also of New Zealand, my cooking oil is measured in metric and mL. There's a good conversions of metric to imperial and imperial to metric, and both U.S. and English imperial terms, search on Google for: "conversions.uk" and there should be a British-government and French-government website there so you can key-in your e.g. mL to convert it to US Imperial, and so forth. In fact, the best of weights and measurements is English Imperial, but many nations are changing to metric, and it seems like that in future, all nations will have the same measurements and capacities, all of it metric. +++ Many recipe books now include conversion tables to save you having to rush off to the computer! Some fluid measurements might be in tea- or table- spoonfuls, too!
The best metric unit for measuring the amount of spices in a batch of cookies is typically teaspoons or tablespoons, depending on the quantity and the recipe. These units are often used in cooking to ensure accurate measurements of small amounts of ingredients like spices.
Ingredients, measurements and directions.
When following a recipe.
To convert granulated garlic to cloves in a recipe, use 1/2 teaspoon of granulated garlic for every clove of fresh garlic called for in the recipe.
Check out the link.
Milligrams.
divide all the measurements by 100.