The Dosage Calculator detects which dose of medicine is appropriate for your weight. The calculator can convert the dose expressed in mg/kg into the dose of liquid medicine.

The text below shows the formula for calculating the dose of the drug and how to use it. You will also learn more about the different types of dosages (types of dosing) that you may encounter when using different drugs. Finally, you will learn the benefits of adjusting the dose to the patient.

Meanwhile, check other calculators on our website such as from the conversion section or maybe you are interested in math category. Further, you can find many interesting calculators in our everyday life category as well.

Dosage forms

Dosage forms (unit doses) are pharmaceutical drugs in the form in which they are placed on the market for use, with a specific mixture of active ingredients and inactive components, in a certain form (such as a capsule shell, for example), and distributed in a certain dose. Depending on the method or route of administration, dosage forms are classified into several types. Types of liquid, solid, and semi-solid dosage forms. Common dosage forms are pills, tablets or capsules, beverages or syrups, and natural or herbal forms.

The most popular method of administration is oral. However, sometimes this method cannot be used because it is ineffective or unavailable due to certain side effects. Therefore, patients can receive medication parenterally. It is subcutaneous, intramuscular, intraosseous, intravenous, etc. Some drugs are given only topically – they are applied directly to the skin or eye, to the rectum or vagina, or as an inhalation.

It should be noted that the drug’s administration method affects its dose and effectiveness. Therefore, you should always check that you are giving the right medicine to the right person in the right way at the right dose!

Dosing types

The therapeutic dose (lat. dosis therapeutica, dosis medicinalis) is the usual amount of drug, which is given for the purpose of treatment and is higher than the minimum one. This amount of medicine can be given at once or divided into several meals. The full dose is the amount of drug in which all the effects of the drug are manifested, while divided doses are intended to achieve only the effect of the pharmacodynamic properties of the drug.

The maximum single dose (lat. dosis maxima singula) is the largest amount of the drug, which has a favorable therapeutic effect and does not cause toxic effects.

The maximum daily dose (lat. dosis maxima pro die) is the maximum amount of drug taken in 24 hours that do not cause toxic effects.

Maximum doses should be considered in all applications where complete absorption of the drug may occur, especially for oral, parenteral, perlingual, and rectal administration and inhalation.

Calculating medication dosage by weight

Calculations of medical doses that consider the patient’s mass are very common in obese patients and in pediatric wards. It’s easy to imagine that an adolescent’s body weight can be 40 times the mass of a newborn, so hopefully, you can spot the need for accurate medication dosing. Some adult-specific medications need to be cure according to the patient’s mass. These include heparin, antibiotics, and muscle relaxants.

Dosage Formulas

If you need to calculate the dosage of the drug, you need to use the following equation:

dosage = weight \times dose

where:

weight – Patient’s weight, expressed in kg or lb. It is important to enter the correct result;
dose – The prescribed amount of the medicate in mg per kg of body mass. This number is available on the medicine box or prescription;
dosage – The total amount of medicine you need to take.

If the medicate is in a liquid state, it is determined differently. After all, how should you know how many ml of your medicine you need to take to ingest, for example, 50 mg of active substance? Our dosage calculator can also help you with this. There is the following formula for this:

fluid \; dose = \frac {dose} {concentration \; of \; drug }

where:

drug concentration – the amount of a substance per given volume of your drug. Unit is mg per ml.

This function of the dosing calculator is particularly useful when children are given liquid medicines (e.g., syrup) and in hospitals, where many medicines are given to the patient not only orally but intravenously. Conversion from mg to ml is necessary in such situations.

Pediatric doses

Special attention we should pay to dosing in children. There are special dosage formulas for calculation. For a child under one year of age, the formula according to Bolognini for therapeutic doses of drugs is:

D = 0,05-m

Where:

D – therapeutic dosage of the medicate for infants in relation to the maximum dosage of the medicate for adults,
m – age of the child (months).

Dosing according to the child’s age is the simplest way to determine the dosage. According to Dilling’s rule:

Pediatric \; dose = \frac {age \; of \; child} {20} \times adult \; dose

The obtained values correspond well to the calculation of the children’s dosage according to body mass.

According to Young’s formula, the obtained values satisfy between the ages of 3 and 12 years; in older children, they are somewhat too small.

Pediatric \; dose = \frac {child \; age} {child \; age +12} \times adult \; dose

Dosage according to the child’s body weight

According to Thiemich-Feer, the child needs a portion of the adult human dosage, which corresponds to a portion of the child’s weight with respect to the average adult human weight of 60-70 kg.

Pediatric \; dose = \frac {child \; weight} {70} \times adult \; dose

Dosage according to the child’s body surface

Determining the child’s body surface area is very complex. The nomogram determines the child’s body surface area based on his height and weight.

Pediatric \; dose = \frac {child \; area} {adult \; area} \times adult \; dose

How to Calculate?

If you want to find the appropriate dosing of the medicate for your body mass, you must follow these steps:

  • Determine the drug dosage. The corresponding dosage of the active substance is 2 mg/kg of body mass.
  • Weigh up. We will say that weight is 80 kg.
  • Multiply these two values to get a dose of medicines in mg: 160 mg

You must take 160 mg of active substance.

What do we do if the medicine is liquid? For example, let’s say the medicate concentration is 2 mg/ml.

Moreover, divide the dose and concentration medicate to obtain the liquid dose result of 80 ml.

Example

Regularly prescribed analgesics and antipyretic oral or rectal doses of paracetamol for children for more than 3 months is 10 to 15 mg to 1 kilogram of weight.

It can be administered every 4 to 6 hours and a maximum of 5 doses in 24 hours. The maximum daily pediatric dosage of paracetamol is 60 mg/kg.

Scenario: We will say that the child is 5 years old and weighs 20 kg. Therefore, we will use the medicine in the form of a liquid of 120 mg/ml of paracetamol.

  • The single pediatric dosage of paracetamol:  20 \; kg \times 15 \; mg/kg = 300 \; mg
  • The maximum daily dosage for your child:  20\; kg \times 60 \;mg/kg = 1200\; mg

The total liquid dose is 10 ml.

FAQ

Why do you have to calculate dosages?

Doses are calculated for accuracy and precision. Therefore, it is very important, especially for children, to pay attention to precise doses because any deviation can lead to unwanted side effects.

What factors do you need to consider when calculating medication dosages?

The patient’s mass and the prescribed dosage must be considered when determining the dosage. Consider in what form the medicate is given. Liquid or tablet, whether it is an elderly person or a child.

How do you calculate mg to mL?

When converting mg in ml, it is important to enter the amount of active ingredient in mg/kg in the calculator and know the person’s mass. Then, we multiply these two values and get how many mg of the substance should be taken. If it is a liquid, we must convert it into ml. We will assume that the active component is expressed instead of mg/kg in mg/ml. Divide the value obtained in mg by the value of the active substance and obtain the value in ml.