How this calculator works
Milligrams measure mass, while teaspoons measure volume. This calculator connects them using a positive density. Food presets come from published baking weights, treating each cup as a US customary cup and dividing it into 48 teaspoons. Water uses an approximate 1 g/mL. A teaspoon contains exactly 4.92892159375 mL; a preset ingredient mass remains approximate because scooping and packing affect it.
Formula
US tsp = mg / (1000 x density in g/mL x 4.92892159375). mg = US tsp x 4.92892159375 x density x 1000. The flour preset uses 120 g per cup, giving approximately 2500 mg per teaspoon.
Worked example
With the flour preset, 5000 mg fills approximately 2 US teaspoons. The honey reference of 21 g per tablespoon gives approximately 7000 mg per teaspoon, so half a teaspoon is about 3500 mg.
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Frequently asked questions
How many milligrams are in one teaspoon?
There is no universal value. The flour preset gives about 2500 mg, while the honey preset gives about 7000 mg in the same US teaspoon.
Does this use a 5 mL teaspoon?
It uses the US customary teaspoon of 4.92892159375 mL. For a 5 mL metric spoon, choose reverse mode, select mL and enter 5.
Why can a tiny mass give a tiny fraction of a spoon?
A milligram is only one thousandth of a gram. Ordinary kitchen spoons cannot reliably measure many of these small calculated fractions; a suitable scale measures the mass directly.
Does this convert a medicine concentration?
No. These food densities are unrelated to the amount of an active ingredient in a solution. The tool does not calculate doses.