MS Excel: PDURATION function for number of periods calculation

PDURATION stands for "Period Duration".It calculates the number of periods needed for an investment to grow from a starting value to an ending value, given a constant rate of return.

If you know your interest rate, your initial investment, and your target value, PDURATION tells you how long it will take to reach your goal.

✅ Growth-focused ➔ Use PDURATION

✅ Want to plan time to double, triple money ➔ Use PDURATION

In personal finance and business planning, knowing how long it takes for your money to grow is crucial. Whether you're planning to double your savings or grow your business revenue, PDURATION makes it easy.

✅ No complicated math

✅ Accurate forecasting

✅ Perfect for compound growth scenarios

Syntax

PDURATION(rate, pv, fv)

Argument	Description
rate	Constant rate of return per period (expressed as a decimal, e.g., 8% = 0.08).
pv	Present Value (starting amount).
fv	Future Value (target amount).

Real-World Example

Imagine:

• You have $10,000 today.

• You want it to grow to $20,000.

• You expect an annual return of 7%.

Excel Formula:

=PDURATION(0.07, 10000, 20000)

Result: Excel will return approximately 10.24 years.

Meaning: At 7% annual return, it would take about 10.24 years for your money to double.

More Unique PDURATION Scenarios

Scenario	Formula	What Happens
Doubling your investment	=PDURATION(0.05, 5000, 10000)	~14.2 years
Tripling your savings	=PDURATION(0.06, 5000, 15000)	~18.85 years
Business revenue goal	=PDURATION(0.10, 100000, 250000)	~9.58 years

Secrets to Master PDURATION Usage

Tip	Why It Matters
Express rate as decimal	7% ➔ 0.07
Ensure fv > pv	Otherwise the result will be negative
Constant growth assumed	Volatile returns make PDURATION less accurate
Works for any compounding period	Annual, monthly, etc., depending on how you define "rate"

PDURATION vs Similar Functions

Function	Purpose	Key Difference
PDURATION	Find how long growth takes	Focused on time calculation
FV	Find future value	Calculates money, not time
NPER	Find number of periods for loans	Based on payments, not growth

Summary Table

Feature	Details
Purpose	Calculate how long it takes for investment growth
When to use	Savings, investment, business planning
Key Inputs	Growth rate, present value, future value
Critical Insight	Assumes constant growth over time

Financial success is not just about how much you invest — it's also about when you reach your goals. PDURATION is a simple yet powerful tool to turn your investment dreams into clear timelines.

Want to know when you'll be a millionaire? Use PDURATION.

Want to plan retirement savings? Use PDURATION.

Want to project business growth? Use PDURATION.

Real-Life Tip

Many personal finance experts recommend using PDURATION to check how different investment strategies (like aggressive vs conservative portfolios) affect the time to reach your goals.Even a 1-2% difference in rate changes the time horizon dramatically!