Scenario 1: Short Half-Life
Initial dose of the drug (mg): 100 mg; Drug's half-life (hours): 2 hours; Time elapsed since administration (hours): 4 hours
Amount of drug remaining in the body (mg): 25 mg; Percentage of drug eliminated: 75 %
Drug Half-Life Calculator
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Estimates how long it takes for half of a drug dose to be eliminated from the body.
More tools:Health Calculators
How To Use
How to use this calculator
Start with your values, or try a preset.
Step 1
Enter Initial dose of the drug (mg), Drug's half-life (hours), and Time elapsed since administration (hours) in the units shown.
Step 2
Read Amount of drug remaining in the body (mg) and Percentage of drug eliminated in the results panel. Results update as you change the inputs.
Step 3
Choose a preset to load an example, then adjust the values for your situation.
Worked Examples
Example calculations
See the inputs and their calculated results.
Scenario 2: Long Half-Life
Initial dose of the drug (mg): 200 mg; Drug's half-life (hours): 12 hours; Time elapsed since administration (hours): 24 hours
Amount of drug remaining in the body (mg): 50 mg; Percentage of drug eliminated: 75 %
Scenario 3: Half-Life of 6 hours
Initial dose of the drug (mg): 150 mg; Drug's half-life (hours): 6 hours; Time elapsed since administration (hours): 12 hours
Amount of drug remaining in the body (mg): 37.5 mg; Percentage of drug eliminated: 75 %
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Important
Use the result as an estimate and confirm any medical decisions with a qualified professional.