Pharmacokinetic Half-Life
Pharmacokinetic Half-Life: calculated with the published clinical method, with result interpretation. A reference tool that does not replace a doctor's advice.
ℹ Reference calculation based on the published method. It does not replace a clinical examination or a doctor's decision.
Pharmacokinetic Half-Life
Concentration 1mg/L
Concentration 2 (later)mg/L
Time between samplesh
Elimination half-life
4h
Elimination rate constant k
0.1733h⁻¹
Near-complete elimination (5 × t½)
20.0h
More about: Pharmacokinetic Half-Life
What it calculates
The “Pharmacokinetic Half-Life” calculator computes Elimination half-life in h from 3 parameters: concentration 1 (mg/L), concentration 2 (later) (mg/L), time between samples (h).
Used by professionals and patients to assess health metrics, dosages, and risks.
Example calculation
With parameters Concentration 1 = 10 mg/L, Concentration 2 (later) = 5 mg/L, Time between samples = 4 h the result is 4 h (First-order kinetics, both samples in the elimination phase).
How to use
- Enter concentration 1, concentration 2 (later) and time between samples — each field above is adjustable with a slider.
- Elimination half-life (h) is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is BMI calculated?
BMI = weight (kg) / height (m)². Example: 70 kg / (1.75 m)² = 22.9. The WHO normal range is 18.5–24.9; below that is underweight, 25–29.9 is overweight, and 30+ is obese.
Is BMI accurate for everyone?
No. BMI does not distinguish muscle from fat, so athletes may show a high BMI with low body fat. It is also less reliable for teenagers, pregnant people, older adults, and very tall or short individuals.
What are the BMI categories?
Underweight: below 18.5. Normal: 18.5–24.9. Overweight: 25–29.9. Obese class I: 30–34.9; class II: 35–39.9; class III: 40+.
What is a better measure than BMI?
Body fat percentage, waist-to-height ratio (aim for under 0.5), and waist circumference give a clearer picture of health than BMI alone.
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