How to use the drug elimination calculator
Find drug amount remaining after time using half-life. Enter initial dose, half-life, time elapsed in the fields above; the remaining, eliminated, time to 97% elimination (5 half-lives) are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- D — Initial dose (mg)
- th — Half-life (h)
- t — Time elapsed (h)
Worked example
With initial dose = 500 mg, half-life = 6 h, time elapsed = 12 h, the calculator gives remaining ≈ 125 mg; eliminated ≈ 75 %; time to 97% elimination (5 half-lives) ≈ 30 h.
Frequently asked questions
What is the formula for the drug elimination calculation?
Remaining (mg) = D × 0.5^(t / th). Eliminated (%) = 100 × (1-[Remaining] / D). Time to 97% elimination (5 half-lives) (h) = 5 × th. Here D is initial dose (mg), th is half-life (h), t is time elapsed (h).
What inputs do I need for the drug elimination calculator?
You need initial dose in mg, half-life in h, time elapsed in h. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.