Rule of 70 Calculator

Use our free Rule of 70 calculator to estimate the doubling time of an investment. The Rule of 70 (Years = 70 / Rate) is often more accurate than the Rule of 72 for lower interest rates and continuous compounding scenarios.

Financial

Calculate

Annual Rate of Return (%)

Desired Doubling Time (years)

years

Principal Amount (optional)

Currency

Formula

The Rule of 70 is a simple formula used to estimate the doubling time of an investment. Divide 70 by the annual rate of return to get the approximate number of years until your money doubles.

Years to Double = 70 / Rate, Rate Needed = 70 / Years

Percentage: The percentage value you want to apply

Number: The original number or value

Result: The calculated result

How It Works

1Choose whether to calculate time to double or rate needed.
2If calculating time: enter the annual rate of return.
3If calculating rate: enter the desired doubling time in years.
4Optionally enter a principal amount to see the future value after doubling.

Examples

7% annual return - how long to double?

1.Years to double = 70 / 7 = 10 years
2.$10,000 becomes $20,000 in approximately 10 years at 7%

Result: 10 years

Frequently Asked Questions

The Rule of 70 estimates doubling time: Years = 70 / Annual Growth Rate. It is often used for continuous compounding and population growth.

The Rule of 70 uses 70 instead of 72 and is more accurate for lower rates (1-5%) and continuous compounding. Rule of 72 is better for moderate rates (6-10%).

The Rule of 69.3 is the most accurate for continuous compounding, as ln(2) ≈ 0.693. The Rule of 70 is a rounded version that's easier for mental math.

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Rule of 70 Explained

CalculateMe Team

Last updated: 2026-07-15

Frequently Asked Questions

The Rule of 70 estimates doubling time: Years = 70 / Annual Growth Rate. It is often used for continuous compounding and population growth.

The Rule of 70 uses 70 instead of 72 and is more accurate for lower rates (1-5%) and continuous compounding. Rule of 72 is better for moderate rates (6-10%).

The Rule of 69.3 is the most accurate for continuous compounding, as ln(2) ≈ 0.693. The Rule of 70 is a rounded version that's easier for mental math.

Rule of 70 Calculator

Formula

How It Works

Examples

7% annual return - how long to double?

Frequently Asked Questions

What is the Rule of 70?

How is Rule of 70 different from Rule of 72?

What is the Rule of 69.3?

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Rule of 70 Calculator

Formula

How It Works

Examples

7% annual return - how long to double?

Frequently Asked Questions

What is the Rule of 70?

How is Rule of 70 different from Rule of 72?

What is the Rule of 69.3?

Related Calculators

Related Articles