Half Life Drug Calculator
Enter a drug dose and its half-life to see how much remains in your body over time.
Use the Half Life Drug Calculator
Drug Parameters
Quick Examples
Enter dose and half-life to see results
Concentration at Elapsed Time
Elapsed Time
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Remaining
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% Remaining
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Concentration Over Time
Elimination Schedule
| Half-Lives | Time Elapsed | Remaining | % Left |
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Summary
The half-life of a drug is the time it takes for half of the drug to be eliminated from the body. This calculator uses the standard exponential decay formula to compute remaining concentration at any point in time. Results are shown as a table and a visual concentration chart.
How it works
- Enter the initial dose (in any unit, e.g. mg).
- Enter the drug's half-life in hours.
- Optionally enter a time elapsed in hours to calculate concentration at that exact moment.
- The calculator applies the formula: C = C₀ × (0.5)^(t / t½).
- A table shows remaining concentration at each half-life interval up to 10 half-lives.
- A bar chart visualizes how the concentration drops over time.
Use cases
- Estimate how long a medication stays active in your system.
- Understand pharmacokinetics for drug interaction research.
- Study theoretical single-dose clearance curves for pharmacology coursework.
- Determine roughly when a drug will be below detectable levels.
- Educational demonstration of exponential decay in pharmacology.
- Demonstrate basic first-order elimination concepts (not for clinical dosing schedules).
Frequently Asked Questions
Last updated: 2026-09-30 ·
Reviewed by Nham Vu