PDURATION Function
Calculates the number of periods required for an investment to reach a specified value.
Syntax
Parameters
| Parameter | Description | Required |
|---|---|---|
| rate | Interest rate per period. | Required |
| pv | Present value of the investment. | Required |
| fv | Future value of the investment. | Required |
Basic Example
Years to double an investment
=PDURATION(0.07, 10000, 20000)At 7% annual interest, it takes about 10.24 years for $10,000 to double to $20,000.
Advanced Examples
Example 1: Months to reach a savings goal
Savings planMonths for $5,000 to grow to $6,000 at 6% annual interest
=PDURATION(0.06/12, 5000, 6000)How PDURATION Works
PDURATION uses the formula ln(fv / pv) / ln(1 + rate) to find the number of periods. It is a simpler way to solve for time in the compound-interest formula.
Important Notes & Limitations
Requires a positive rate.
Result is in the same unit as the rate (years, months, etc.).
Does not include contributions or withdrawals.
Common Errors & Fixes
#NUM! errorRate is zero or negative, or pv and fv have different signs.Fix: Use a positive rate and ensure fv > pv for growth.
Wrong period unitAnnual rate was used but result interpreted as months.Fix: Use a rate that matches the desired period unit.
Download Practice File
PDURATION
pdurationPractice PDURATION with Real Data
Download a sample CSV file with pre-populated data and practice exercises for the PDURATION function. Works in both Excel and Google Sheets.
File format: CSV (comma-separated values) - opens in Excel, Google Sheets, and all spreadsheet apps