Half-Life Calculator

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Calculate the half-life of a radioactive isotope or substance over time.

Initial Quantity (N₀)

Half-Life Time (t½)

Elapsed Time (t) Ensure time units match the Half-Life time unit.

Calculate Exponential Decay and Half-Life

In physics and chemistry, half-life is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay.

Our Half-Life Calculator uses the standard exponential decay formula Nt = N0 * (1/2)^(t / t½). You just need to enter the starting quantity, the half-life duration of the substance, and the amount of time that has passed. The tool will calculate exactly how much of the substance remains.

자주 묻는 질문

It is the time required for one-half of the atomic nuclei of a radioactive sample to decay into another nuclear form.

Yes! Biological half-life describes how long it takes for a substance (like a drug) to lose half of its pharmacological activity in the body. The mathematical formula is exactly the same.

Mathematically, exponential decay never reaches absolute zero. However, practically speaking, after about 10 half-lives, the remaining amount (less than 0.1%) is considered negligible.