The mg to mL calculator helps you convert the weight of a liquid which has the density of water to a volume - a conversion from units of milligrams to units of milliliters. As well as a mg to mL conversion, you can also use the calculator backwards to perform a mL to mg conversion.

Read on to learn about the historical relationship between the units of milligrams and milliliters.

How many mg in a mL?

So exactly how many milligrams are there in a milliliter? The first step to answering this question is to understand what the letter 'm' means when applied to units. It means one-thousandth (1/1000) of the original unit. Therefore we're asking how many thousandths of a gram are there in a thousandth of a liter. Recall that a gram is one-thousandth of a kilogram. Now that we've sorted that out, the question is now "What is the relationship between kilograms and liters?"

The kilogram was originally defined in 1795 as equal to one liter of water at the temperature of melting ice (0 °C / 32 °F). That's not entirely true in the present day, as the kilogram and meter (a liter is the volume of one-thousandths of a cubic meter) have been re-defined, but it's a very close indeed (0.9998 kg is a more precise figure).

So, a milligram is a thousandth of a thousandth of a kilogram, and a milliliter is a thousandth of a liter. Notice there is an extra thousandth on the weight unit. Therefore, there must be 1,000 milligrams in a milliliter, making the formula for mg to ml conversion:

  • mL = mg / 1000.

mL to mg conversion - ml to mg calculator

To perform the reverse conversion, i.e., how many mg in ml, we rearrange the above equation in terms of mg, which gives:

  • mg = 1000 * mL

Notice that the ml to mg calculator works in both directions. Just enter the value you know, and the other will appear in no time!

How to use this mg to mL conversion calculator?

The mg to ml calculator is straightforward to use, as you need to provide only one value. If you're still not sure how to use it, here's a short set of instructions:

  1. To perform mg to mL conversion, enter the number of milligrams into the first row of the calculator.
  2. There is also the option of using other weight units by clicking on the units drop-down menu.
  3. We will then display the number of milliliters. Again, you can also express the quantity of liquid in terms of other units.
  4. To perform the reverse mL to mg conversion, enter the number of milliliters first.
  5. If you want to perform a mg to mL conversion of a liquid other than water, click on "Water" to choose a different liquid. Select the option "Other" to input a custom density that matches the liquid used.

Example of mg to mL conversion

Let's say you have 5 grams of water, which is 5,000 mg. Dividing by 1,000, as shown in the mg to mL formula, gives an answer of 5 mL.

Liquid concentrations - how many milligrams in a milliliter

Closely related to liquid density is liquid concentration. You will often see on the packet of a medicine in liquid form that the concentration is given in mg/mL. If you click the advanced mode button of this calculator, you will see that the default unit is mg/mL. Change the value to match the medicine.

For example, let's say it's 20 mg/mL, so you enter that into the calculator. If you then want to know the volume of liquid that contains 50 mg of medicine, enter 50 mg into the first row of the calculator and you'll find that the answer is 2.5 mL.

Steven Wooding