1. What is Half-Life Percentage?

The half-life percentage remaining calculates how much of a substance remains after a given time based on its half-life. It's commonly used in radioactive decay, pharmacokinetics, and chemical kinetics.

2. How Does the Calculator Work?

The calculator uses the half-life percentage formula:

Where:

• \( t \) — Elapsed time (any time units)
• \( t_{1/2} \) — Half-life (same units as elapsed time)
• 0.5 — Represents the 50% remaining after one half-life

Explanation: The formula calculates the fraction remaining after each half-life period and converts it to a percentage.

3. Importance of Half-Life Calculation

Details: Half-life calculations are essential for determining drug dosing intervals, radioactive material safety, and understanding chemical reaction rates.

4. Using the Calculator

Tips: Enter the elapsed time and half-life in consistent units (both in hours, days, years, etc.). The result will be the percentage of the original amount remaining.

5. Frequently Asked Questions (FAQ)

Q1: What does 50% remaining mean?
A: It means one half-life has passed, and half of the original substance remains.

Q2: How many half-lives until almost nothing remains?
A: After about 7 half-lives, less than 1% remains (0.78% exactly).

Q3: Can this be used for drug half-life?
A: Yes, it works for any first-order decay process including drug elimination.

Q4: Why does the formula use 0.5?
A: The 0.5 represents the fraction remaining after one half-life (50%).

Q5: Does temperature affect half-life?
A: For radioactive decay, no. For chemical processes and drug metabolism, yes - temperature can change reaction rates.