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Both calculators run independently — change the inputs on either side to compare results.
Financial
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.
Fill in the required fields to see your result.
Economics
Compound Interest Calculator
Project the future value of a lump-sum investment when interest is reinvested each year using A = P · (1 + r)ᵗ. The simplest compounding model — assumes annual compounding, a constant rate, and no additional contributions or withdrawals.
Fill in the required fields to see your result.
Key differences
| Doubling Time Calculator | Compound Interest Calculator | |
|---|---|---|
| Category | Financial | Economics |
| Inputs required | 2 | 3 |
| Result | Time to Double (years) | Final Amount ($) |
| 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 the future value of a lump-sum investment when interest is reinvested each year using A = P · (1 + r)ᵗ. The simplest compounding model — assumes annual compounding, a constant rate, and no additional contributions or withdrawals. |