Radioactive Decay Constant Calculator

Calculate decay constant from half-life, mean lifetime, or activity

Calculation Method:

Time Unit:

Half-Life (seconds):

Common Isotopes:

From Half-Life: lambda = ln(2) / t_1/2 = 0.693 / t_1/2

From Mean Lifetime: lambda = 1 / tau

From Activity: lambda = A / N

Relationship: tau = 1/lambda = t_1/2 / ln(2) ≈ 1.443 × t_1/2

The decay constant represents the probability per unit time that a nucleus will decay.

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MyCalcBuddy Editorial Team

This page is maintained as an educational calculator reference.

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Formula Source: University Physics

by Young & Freedman

ðŸ”„Last reviewed: May 2026

âœ“Formula checks are based on standard references and internal QA review.