Calculators

How long until your money doubles - at a steady annual return?

Time to 100% Return

Set your expected return
12%
1%100%

Doesn’t change the time - it only personalises the “₹X → ₹Y” copy below.

At 12% a year, ₹10.00 L grows to ₹20.00 L - a 100% return - in about 6.12 years.

Rule of 72 estimates ~6.00 years (72 ÷ 12). The exact formula gives 6.12 years - within ~2% of the shortcut, which is why the rule is so handy for mental math.

Exact formula vs Rule of 72

Same slider - two ways to estimate. Bar length scales to the larger value so you can see how close the shortcut lands.

Exact (ln 2 ÷ ln(1+r))6.12 yrs
Rule of 72 (72 ÷ rate)6.00 yrs
Gap: 0.12 yrs (~1.9% vs exact)

Doubling time by return rate

Tap a row to jump the slider - bar length is years to double (longer = more years of compounding needed).

6.1163
Exact years (ln 2 / ln(1+r))
6.00 yrs
Rule of 72 estimate
~1.9%
Shortcut vs exact

Assumes a constant annual return and annual compounding (end-of-year). Real markets are not smooth; taxes, fees, and volatility change outcomes. Illustrative only - not investment advice.

Time to double your investment

Doubling time is one of the most intuitive ways to compare return assumptions, whether you are modelling equity CAGR, debt yields, or a PMS track record.

Exact vs Rule of 72

Exact years to double = ln(2) ÷ ln(1 + r), where r is the annual rate as a decimal. Rule of 72 works well between ~6% and 15%; it drifts at very high or low rates.

Why this matters for Indian investors

Small changes in assumed return shift doubling time materially. At 15% it takes ~5 years; at 10% it takes ~7.3 years. Use this before anchoring on headline CAGR from any product page.

Illustrative only — not investment advice. Past scenarios do not guarantee future results. Consult a qualified professional before investing.