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Amount of liquid
Total Mass:
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Based on water density
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About

Converting milliliters (ml) to milligrams (mg) is a common task in pharmacology, nursing, and chemistry. Unlike simple unit changes, this conversion requires knowledge of the substance's density or concentration. One milliliter of water weighs exactly 1,000 mg, but liquids like syrups, mercury, or oil have different densities, altering the resulting mass.

This tool prevents dosage errors by mandating a density input. In medical contexts, "concentration" is often listed on the bottle (e.g., 20 mg/ml). If you are working with pure substances, you need the physical density (usually in g/ml). Getting this variable right is critical for patient safety, especially in pediatric or geriatric dosing where margins for error are slim.

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Formulas

The calculation depends on the unit of the density provided. The base physics formula involves volume and density:

m = V × ρ

Where:

  • m = Mass (mg)
  • V = Volume (ml)
  • ρ = Density

Case 1: Density in g/ml (Standard physical property)

Mass(mg) = V(ml) × D(g/ml) × 1,000

Case 2: Concentration in mg/ml (Common on medicine labels)

Mass(mg) = V(ml) × Conc(mg/ml)

Reference Data

SubstanceDensity (g/ml)1 ml equals...5 ml (tsp) equals...
Water (Standard)1.01,000 mg5,000 mg
Ethanol0.789789 mg3,945 mg
Olive Oil0.92920 mg4,600 mg
Milk1.031,030 mg5,150 mg
Glycerin1.261,260 mg6,300 mg
Honey1.421,420 mg7,100 mg
Mercury13.5313,530 mg67,650 mg
Liquid Suspension (Light)~1.11,100 mg5,500 mg
Syrup (Dense)~1.31,300 mg6,500 mg

Frequently Asked Questions

No. This is only true for pure water at standard temperature. Substances like oil are lighter (approx. 920 mg per ml), while syrups are heavier (approx. 1300 mg per ml). Always check the density.
For medications, look for the concentration on the label, usually written as "X mg/ml". For chemical substances, refer to a Material Safety Data Sheet (MSDS) or standard physical constant tables.
Yes, but be aware that culinary density varies significantly. For example, the density of flour changes based on how packed it is. Liquids like milk, oil, and water are consistent and safe to convert.
g/ml is Grams per Milliliter (standard physical density). mg/ml is Milligrams per Milliliter (often used for medical solution concentrations). Note that 1 g/ml = 1000 mg/ml.