mg to Teaspoon Converter
Milligrams measure mass and teaspoons measure volume, so you need the density of your ingredient to move between them. Pick your substance from the list (or enter a custom density), type your milligram amount, and the teaspoon result updates instantly. Switch between US teaspoons (4.929 mL) and metric teaspoons (5 mL), and use the reverse field to go from teaspoons back to milligrams.
Why you need density to convert mg to teaspoons
Milligrams (mg) measure mass - how much matter something contains. Teaspoons (tsp) measure volume - how much space something occupies. These are different physical quantities, so there is no single universal conversion factor. The bridge between them is density: mass per unit volume, measured in grams per millilitre (g/mL). The formula is: teaspoons = milligrams / (density in g/mL x teaspoon volume in mL x 1000). For water at room temperature, density is 1.00 g/mL, so one US teaspoon holds 4,929 mg. For honey, density is 1.42 g/mL, so one teaspoon holds 6,999 mg. For light, fluffy powders like oats or cake flour, density can be as low as 0.41 g/mL, so a teaspoon holds far less mass.
US vs metric teaspoon
In the United States, one teaspoon equals exactly 4.92892 mL. The international metric teaspoon is exactly 5 mL. The difference is small (less than 1.5%) but matters for precise measurements. Most US recipes and US-labelled supplements use the US teaspoon. Australian, British, and European sources typically use the metric teaspoon. Canadian recipes may use either. This calculator lets you choose which standard applies to your situation.
Practical uses: cooking, supplements, and pharmaceuticals
In cooking, mg-to-teaspoon conversions come up when a recipe specifies an ingredient by mass but your tools only measure volume. Spices like salt, cinnamon, and garlic powder are often listed in milligrams on nutrition labels, while recipe instructions say "half a teaspoon." For supplements, many powder products list a serving as a number of milligrams; this tool converts that to the teaspoon amount you should scoop. For liquid medications that come with a teaspoon measurement guide, the density of the liquid determines the mass in each dose. Note: for any medication, always follow your pharmacist or physician guidance - do not rely solely on a general converter.
Common conversions at a glance
Water: 1,000 mg = about 0.203 US tsp. Table salt: 1,000 mg = about 0.167 US tsp (roughly 1/6 tsp). Granulated sugar: 1,000 mg = about 0.239 US tsp. All-purpose flour: 1,000 mg = about 0.383 US tsp. Honey: 1,000 mg = about 0.143 US tsp. These vary because each substance has a different density. The reverse conversions are equally useful: 1 US tsp of table salt = about 5,997 mg (roughly 6 g), a key figure for tracking daily sodium intake relative to the FDA-recommended limit of 2,300 mg per day.
Common ingredient densities and mg per teaspoon (US)
| Ingredient | Density (g/mL) | mg per US tsp | mg per metric tsp |
|---|---|---|---|
| Water | 1.000 | 4,929 | 5,000 |
| Milk, whole | 1.030 | 5,077 | 5,150 |
| Honey | 1.420 | 6,999 | 7,100 |
| Corn syrup | 1.330 | 6,556 | 6,650 |
| Granulated sugar | 0.850 | 4,190 | 4,250 |
| Powdered sugar | 0.560 | 2,760 | 2,800 |
| Brown sugar | 0.930 | 4,584 | 4,650 |
| Table salt | 1.217 | 5,997 | 6,085 |
| Baking soda | 1.200 | 5,915 | 6,000 |
| Baking powder | 0.900 | 4,436 | 4,500 |
| All-purpose flour | 0.530 | 2,612 | 2,650 |
| Cocoa powder | 0.520 | 2,563 | 2,600 |
| Cinnamon | 0.560 | 2,760 | 2,800 |
| Garlic powder | 0.720 | 3,549 | 3,600 |
| Olive oil | 0.910 | 4,485 | 4,550 |
| Butter | 0.910 | 4,485 | 4,550 |
| Oats | 0.410 | 2,021 | 2,050 |
Based on US teaspoon volume of 4.929 mL. Values are approximate: packing and moisture affect dry goods.
Frequently asked questions
How many mg are in a teaspoon?
It depends on the substance. For water, 1 US teaspoon holds about 4,929 mg. For table salt (density 1.217 g/mL), it holds about 5,997 mg. For all-purpose flour (density 0.53 g/mL), it holds only about 2,612 mg. There is no single "mg per teaspoon" that applies to all materials - you always need to account for the ingredient density.
How do I convert mg to teaspoons without knowing the density?
If you do not know the density, the closest practical default is water (1.00 g/mL): divide your mg value by 4,929 for US teaspoons or by 5,000 for metric teaspoons. This is accurate for water-like liquids (broths, juice, thin sauces) but will be incorrect for denser liquids like honey or for dry powders. Always choose the most appropriate ingredient in the dropdown for the best result.
Is the density of salt 1.217 g/mL?
Yes, for fine table salt the commonly used bulk density is approximately 1.217 g/mL, which gives about 5,997 mg (roughly 6 g) per US teaspoon. This matches USDA nutrient database values that list one teaspoon of table salt at about 6 g. Note that coarse salts like kosher salt or sea salt have lower bulk densities because the larger crystals leave more air space, so the same measured teaspoon contains less mass.
What is the difference between US and metric teaspoons?
A US teaspoon is 4.92892 mL, defined as 1/6 of a US fluid ounce. A metric teaspoon is exactly 5 mL, used in Australia, Canada (often), and many international contexts. The difference is about 1.4%. For most cooking this is negligible, but when tracking supplement doses in milligrams the choice of teaspoon standard can matter.
Can I use this calculator for medication doses?
This calculator can help you understand the relationship between milligrams and teaspoons for a given liquid density, but medication doses should always be confirmed with a pharmacist or physician. Many liquid medications come with dedicated dosing spoons or syringes that are calibrated to the specific product. Never substitute a general converter for professional medical guidance.
Why does flour have such a low density?
Flour is a fine powder and, when spooned loosely into a measuring cup or teaspoon, traps a lot of air between the particles. This gives all-purpose flour a bulk density of about 0.53 g/mL, roughly half that of water. Sifted flour is even lighter. Recipes often call for flour by volume precisely because of this variability - for the most consistent baking results, measuring flour by mass (grams or milligrams) is far more accurate than by volume.
How do I convert teaspoons back to milligrams?
Use the reverse field in this calculator: enter your teaspoon amount in the "Teaspoons (reverse)" field and the milligram equivalent updates automatically. The formula is: milligrams = teaspoons x density (g/mL) x teaspoon volume (mL) x 1000. For example, 2 US teaspoons of granulated sugar = 2 x 0.85 x 4.929 x 1000 = approximately 8,379 mg.