# How long does it take to double money in Excel

Use NPER with a present value of -1 and a future value of 2: `=NPER(B2,0,-1,2)` gives the years to double.

**Excel:** `=NPER(B2,0,-1,2)` (Every current version)

**Google Sheets:** the same formula works.

## Example

Sample data (row 1 is the header):

| A | B |
| --- | --- |
| Investment | Value |
| Annual return | 0.07 |
| Years to double |  |

Formula in B3: `=NPER(B2,0,-1,2)`

Result: 10.2

## How it works

NPER counts the periods for 1 to grow into 2 at the given rate, with no payments in between. At 7% a year that takes 10.2 years. The amounts don't matter, only the ratio, which is why 1 and 2 are enough.

## Other ways

- `=LN(2)/LN(1+B2)`: The exact math behind it: the logarithm of 2 divided by the logarithm of the growth factor.
- `=72/(B2*100)`: The rule of 72, a mental shortcut: 72 divided by the percentage. (Rule of 72: 10.3 years.)

## Common mistakes

- Use the rate per period. For a monthly rate, the result is in months.
- The rule of 72 drifts at high rates; at 20% it says 3.6 years against an exact 3.8.

## Questions

**How long to triple money?**

Use 3 as the future value: `=NPER(B2,0,-1,3)`.

**What return do I need to double in 8 years?**

Use RATE: `=RATE(8,0,-1,2)`, about 9.05%.

Every formula and result on this page was checked by running it in the Spreadsheet Practice formula engine on 2026-10-30.

Source: https://spreadsheetpractice.com/formulas/how-long-to-double-money