Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Doubling Time Calculator

Find how many years it takes an investment to double at a given rate and compounding frequency. A precise alternative to the Rule of 72.

Annual Interest Rate (%)

Compounding Periods per Year (periods)

Financial

Future Value Calculator

Project what a lump sum plus regular yearly contributions will grow to at a given rate of return. Use it to forecast investments, savings plans, and retirement balances.

Present Value (starting amount) ($)

Annual Return Rate (%)

Number of Years (years)

Annual Contribution ($)

Key differences

	Doubling Time Calculator	Future Value Calculator
Category	Financial	Financial
Inputs required	2	4
Result	Time to Double (years)	Future Value ($)
What it does	Find how many years it takes an investment to double at a given rate and compounding frequency. A precise alternative to the Rule of 72.	Project what a lump sum plus regular yearly contributions will grow to at a given rate of return. Use it to forecast investments, savings plans, and retirement balances.