Rule of 72 Calculator

Calculate how long it takes for an investment to double at a given annual interest rate using the Rule of 72 mental math versus the exact logarithmic formula.

Rule of 72 — interactive calculator, computed instantly in your browser.

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Complete Guide to Rule of 72 Calculator

Precision calculations using verified mathematical formulas, computed directly in your browser.

🔗 Investment Growth Estimates

The Rule of 72 is a quick heuristic to estimate doubling time for compounding investments. For more precise multi-variable forecasting, use our comprehensive 💰 Financial Hub.

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Frequently Asked Questions (Rule of 72)

What is the difference between Simple Interest and Compound Interest?

Simple interest is calculated solely on the principal amount (I = Prt), whereas compound interest calculates interest on both the principal and previously accumulated interest (A = P(1+r/n)^nt).

What is Loan Amortization?

Loan amortization is the process of spreading a loan into a series of equal periodic payments. Each payment is split between paying off interest fees and reducing the principal balance.

What is the difference between Margin and Markup?

Margin is profit expressed as a percentage of selling price (Revenue), while Markup is profit expressed as a percentage of Cost of Goods Sold (COGS). A 50% markup equals a 33.3% gross profit margin.