Unfortunately there isn't one simple equation to fit all, in where you are able to convert milligrams (mg) into so much of a fraction of a teaspoon, essentially millilitres (ml). One level teaspoon will hold approximately five ml of fluid. The reason why this conversion is impossible without more information is that different substances have different densities, so they will each by definition weigh, at times significantly different to other substances.
Traditional kitchen scales are affordable but will generally only measure weights in ounces (oz) pounds (lb) grams (g) and kilograms (kg) which is nowhere near the level of precision required to accurately measure out 10 mg, although depending on how accurate the measurement needs to be it would be possible, albeit time consuming and immensely fiddly, to measure out a gram of your specific substance using regular kitchen scale and then split the measurement again, by sight, into 100 equal piles, which should then very crudely equate to 10 mg. Naturally depending on what is being measured then the slightest anomaly could prove dangerous.
Obtaining a pair of laboratory scales that measures to the nearest micro-gram will yield the most accurate results, although these can cost upwards of thousands of dollars. Milligram balances are also extremely sensitive but are much more affordable, starting at around $200. There are a number of alternative budget scales that claim to measure accurately to the nearest milligram that can cost a tenth of that, however the exactness of such cheap instruments may be unreliable.
Traditional kitchen scales are affordable but will generally only measure weights in ounces (oz) pounds (lb) grams (g) and kilograms (kg) which is nowhere near the level of precision required to accurately measure out 10 mg, although depending on how accurate the measurement needs to be it would be possible, albeit time consuming and immensely fiddly, to measure out a gram of your specific substance using regular kitchen scale and then split the measurement again, by sight, into 100 equal piles, which should then very crudely equate to 10 mg. Naturally depending on what is being measured then the slightest anomaly could prove dangerous.
Obtaining a pair of laboratory scales that measures to the nearest micro-gram will yield the most accurate results, although these can cost upwards of thousands of dollars. Milligram balances are also extremely sensitive but are much more affordable, starting at around $200. There are a number of alternative budget scales that claim to measure accurately to the nearest milligram that can cost a tenth of that, however the exactness of such cheap instruments may be unreliable.