Exponential Growth & Decay Calculator
Model exponential growth or decay processes. Enter an initial value, growth or decay rate, and number of periods to find the final value, doubling or halving time, and period-by-period progression.
Exponential growth and decay describe processes where the rate of change is proportional to the current value. The formula is A = P x (1 + r)^t, where P is the initial value, r is the rate per period, and t is the number of periods.
Doubling and halving time: For growth, the doubling time is ln(2) / ln(1 + r). For decay, the halving time (half-life) uses the same formula with ln(0.5). At 7% growth, the doubling time is about 10.24 periods, close to the Rule of 72 estimate (72/7 = 10.3).
Applications: Exponential models appear throughout science and finance: population growth, compound interest, radioactive decay, bacterial cultures, viral spread, depreciation, and drug metabolism. Real-world growth is often exponential only for limited periods before other factors (resource limits, competition) cause it to slow.